Maximal Repetitions in Written Texts: Finite Energy Hypothesis vs. Strong Hilberg Conjecture
Directory of Open Access Journals (Sweden)
Łukasz Dębowski
2015-08-01
Full Text Available The article discusses two mutually-incompatible hypotheses about the stochastic mechanism of the generation of texts in natural language, which could be related to entropy. The first hypothesis, the finite energy hypothesis, assumes that texts are generated by a process with exponentially-decaying probabilities. This hypothesis implies a logarithmic upper bound for maximal repetition, as a function of the text length. The second hypothesis, the strong Hilberg conjecture, assumes that the topological entropy grows as a power law. This hypothesis leads to a hyperlogarithmic lower bound for maximal repetition. By a study of 35 written texts in German, English and French, it is found that the hyperlogarithmic growth of maximal repetition holds for natural language. In this way, the finite energy hypothesis is rejected, and the strong Hilberg conjecture is partly corroborated.
Clock hypothesis of relativity theory, maximal acceleration, and Mössbauer spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Potzel, W., E-mail: wpotzel@ph.tum.de [Technische Universität München, Physik-Department E15 (Germany)
2016-12-15
Results obtained several years ago using the high-resolution 93.3 keV Mössbauer resonance in {sup 67}ZnO and β{sup ′}-brass have been reanalyzed with the notion that the clock hypothesis of Special Relativity Theory is not sufficient, but that a maximal acceleration a{sub m} exists and that an acceleration a contributes to the temperature dependence of the center shift by a term ±(1/2)(a/a{sub m}){sup 2}. The significance of the sign of this term is discussed in detail. For both substances a lower limit of a{sub m}>1.5⋅10{sup 21}m/s {sup 2} is inferred which is more than two orders of magnitude larger than - and thus excludes - the value a{sub m}=1⋅10{sup 19}m/s {sup 2} suggested by {sup 57}Fe rotor experiments.
Neoclassical transport in NCSX
International Nuclear Information System (INIS)
Mikkelsen, D.R.; Zarnstorff, M.C.; Beidler, C.D.; Maassberg, H.; Houlberg, W.A.; Spong, D.A.; Tribaldos, V.
2003-01-01
Methods for calculating neoclassical transport in the National Compact Stellarator Experiment (NCSX) are discussed, with particular attention to developing computationally inexpensive predictions of neoclassical transport. (orig.)
Directory of Open Access Journals (Sweden)
Sana Ullah Jan
2018-03-01
Full Text Available A framework of spectrum sensing with a multi-class hypothesis is proposed to maximize the achievable throughput in cognitive radio networks. The energy range of a sensing signal under the hypothesis that the primary user is absent (in a conventional two-class hypothesis is further divided into quantized regions, whereas the hypothesis that the primary user is present is conserved. The non-radio frequency energy harvesting-equiped secondary user transmits, when the primary user is absent, with transmission power based on the hypothesis result (the energy level of the sensed signal and the residual energy in the battery: the lower the energy of the received signal, the higher the transmission power, and vice versa. Conversely, the lower is the residual energy in the node, the lower is the transmission power. This technique increases the throughput of a secondary link by providing a higher number of transmission events, compared to the conventional two-class hypothesis. Furthermore, transmission with low power for higher energy levels in the sensed signal reduces the probability of interference with primary users if, for instance, detection was missed. The familiar machine learning algorithm known as a support vector machine (SVM is used in a one-versus-rest approach to classify the input signal into predefined classes. The input signal to the SVM is composed of three statistical features extracted from the sensed signal and a number ranging from 0 to 100 representing the percentage of residual energy in the node’s battery. To increase the generalization of the classifier, k-fold cross-validation is utilized in the training phase. The experimental results show that an SVM with the given features performs satisfactorily for all kernels, but an SVM with a polynomial kernel outperforms linear and radial-basis function kernels in terms of accuracy. Furthermore, the proposed multi-class hypothesis achieves higher throughput compared to the
Large orbit neoclassical transport
International Nuclear Information System (INIS)
Lin, Z.; Tang, W.M.; Lee, W.W.
1997-01-01
Neoclassical transport in the presence of large ion orbits is investigated. The study is motivated by the recent experimental results that ion thermal transport levels in enhanced confinement tokamak plasmas fall below the open-quotes irreducible minimum levelclose quotes predicted by standard neoclassical theory. This apparent contradiction is resolved in the present analysis by relaxing the basic neoclassical assumption that the ions orbital excursions are much smaller than the local toroidal minor radius and the equilibrium scale lengths of the system. Analytical and simulation results are in agreement with trends from experiments. The development of a general formalism for neoclassical transport theory with finite orbit width is also discussed. copyright 1997 American Institute of Physics
COMPETITION: CLASSICAL VERSUS NEOCLASSICAL VIEW
Mihaela Cornelia Sandu
2013-01-01
Competition is an important element from economical theory. Over time it has experienced several definitions and classifications much of them being contradictory. In this paper I will make a parallel between classical and neoclassical point of view according to competition. Keywords. Competition; neoclassical theory; classical theory; monopolistic; perfect competition.
Neoclassical Theory and Its Applications
Energy Technology Data Exchange (ETDEWEB)
Shaing, Ker-Chung [Univ. of Wisconsin, Madison, WI (United States)
2015-11-20
The grant entitled Neoclassical Theory and Its Applications started on January 15 2001 and ended on April 14 2015. The main goal of the project is to develop neoclassical theory to understand tokamak physics, and employ it to model current experimental observations and future thermonuclear fusion reactors. The PI had published more than 50 papers in refereed journals during the funding period.
Neoclassical transport in toroidal systems
International Nuclear Information System (INIS)
Wobig, H.
1992-01-01
The neoclassical theory of general toroidal equilibria is reformulated. The toroidal equilibrium of tokamaks and stellarators are described in Hamada coordinates. The relevant geometrical parameters are identified and it is shown how the reduction of Pfirsch-Schluter currents affects neoclassical transport and bootstrap effects. General flux-friction relations between thermodynamic forces and fluxes are derived. In drift-kinetic approximation the neoclassical transport coefficients are Onsager symmetric. Since a toroidal loop voltage is included, the theory is valid for all toroidal systems. (Author)
Experimental study of neoclassical currents
International Nuclear Information System (INIS)
Zarnstorff, M.C.; Prager, S.C.
1985-05-01
A detailed experimental study is presented of the bootstrap and Pfirsch-Schlueter currents that are predicted by neoclassical transport theory. In a toroidal octupole, on magnetic surfaces within the separatrix, the observed parallel plasma currents are in excellent quantitative agreement with neoclassical theory with regard to the spatial structure (along a magnetic surface), collisionality dependence and toroidal magnetic field dependence. On magnetic surfaces outside the separatrix, the ion portion of the parallel current is in agreement with neoclassical theory but the electron parallel current is observed to obtain a unidirectional component which deviates from and exceeds the theoretical prediction
Neoclassical equilibrium in gyrokinetic simulations
International Nuclear Information System (INIS)
Garbet, X.; Dif-Pradalier, G.; Nguyen, C.; Sarazin, Y.; Grandgirard, V.; Ghendrih, Ph.
2009-01-01
This paper presents a set of model collision operators, which reproduce the neoclassical equilibrium and comply with the constraints of a full-f global gyrokinetic code. The assessment of these operators is based on an entropy variational principle, which allows one to perform a fast calculation of the neoclassical diffusivity and poloidal velocity. It is shown that the force balance equation is recovered at lowest order in the expansion parameter, the normalized gyroradius, hence allowing one to calculate correctly the radial electric field. Also, the conventional neoclassical transport and the poloidal velocity are reproduced in the plateau and banana regimes. The advantages and drawbacks of the various model operators are discussed in view of the requirements for neoclassical and turbulent transport.
Neoclassical transport in ERS regime
International Nuclear Information System (INIS)
Lin, Z.; Tang, W.; Lee, W.W.
1996-01-01
The core ion thermal conductivity has been observed to fall below the standard neoclassical level in recent TFTR reversed magnetic shear discharges. Due to the combination of high central q and small local inverse aspect ratio, the ion poloidal gyroradius can be larger than the minor radius and comparable to the pressure gradient scale length in this ERS regime. It is then expected that finite orbit width effects play a key role in modifying the standard picture of neoclassical transport. Specifically, both the trapped particle fraction and the banana orbit width axe reduced by the finite minor radius and possibly by the pressure-gradient-driven radial electric field. In addition, the steep pressure gradient can generate neoclassical poloidal flows which, in turn, could reduce the particle and heat transports. Results from analytic estimates as well as those from full toroidal gyrokinetic neoclassical simulations will be presented
Neoclassical MHD equations for tokamaks
International Nuclear Information System (INIS)
Callen, J.D.; Shaing, K.C.
1986-03-01
The moment equation approach to neoclassical-type processes is used to derive the flows, currents and resistive MHD-like equations for studying equilibria and instabilities in axisymmetric tokamak plasmas operating in the banana-plateau collisionality regime (ν* approx. 1). The resultant ''neoclassical MHD'' equations differ from the usual reduced equations of resistive MHD primarily by the addition of the important viscous relaxation effects within a magnetic flux surface. The primary effects of the parallel (poloidal) viscous relaxation are: (1) Rapid (approx. ν/sub i/) damping of the poloidal ion flow so the residual flow is only toroidal; (2) addition of the bootstrap current contribution to Ohm's laws; and (3) an enhanced (by B 2 /B/sub theta/ 2 ) polarization drift type term and consequent enhancement of the perpendicular dielectric constant due to parallel flow inertia, which causes the equations to depend only on the poloidal magnetic field B/sub theta/. Gyroviscosity (or diamagnetic vfiscosity) effects are included to properly treat the diamagnetic flow effects. The nonlinear form of the neoclassical MHD equations is derived and shown to satisfy an energy conservation equation with dissipation arising from Joule and poloidal viscous heating, and transport due to classical and neoclassical diffusion
Neoclassical transport simulations for stellarators
International Nuclear Information System (INIS)
Turkin, Y.; Beidler, C. D.; Maassberg, H.; Murakami, S.; Wakasa, A.; Tribaldos, V.
2011-01-01
The benchmarking of the thermal neoclassical transport coefficients is described using examples of the Large Helical Device (LHD) and TJ-II stellarators. The thermal coefficients are evaluated by energy convolution of the monoenergetic coefficients obtained by direct interpolation or neural network techniques from the databases precalculated by different codes. The temperature profiles are calculated by a predictive transport code from the energy balance equations with the ambipolar radial electric field estimated from a diffusion equation to guarantee a unique and smooth solution, although several solutions of the ambipolarity condition may exist when root-finding is invoked; the density profiles are fixed. The thermal transport coefficients as well as the ambipolar radial electric field are compared and very reasonable agreement is found for both configurations. Together with an additional W7-X case, these configurations represent very different degrees of neoclassical confinement at low collisionalities. The impact of the neoclassical optimization on the energy confinement time is evaluated and the confinement times for different devices predicted by transport modeling are compared with the standard scaling for stellarators. Finally, all configurations are scaled to the same volume for a direct comparison of the volume-averaged pressure and the neoclassical degree of optimization.
Neo-classical impurity transport
International Nuclear Information System (INIS)
Stringer, T.E.
The neo-classical theory for impurity transport in a toroidal plasma is outlined, and the results discussed. A general account is given of the impurity behaviour and its dependence on collisionality. The underlying physics is described with special attention to the role of the poloidal rotation
International Nuclear Information System (INIS)
Furuya, Atsushi; Yagi, Masatoshi; Itoh, Sanae-I.
2003-01-01
The linear neoclassical tearing mode is investigated using the four-field reduced neoclassical MHD equations, in which the fluctuating ion parallel flow and ion neoclassical viscosity are taken into account. The dependences of the neoclassical tearing mode on collisionality, diamagnetic drift and q profile are investigated. These results are compared with the results from the conventional three-field model. It is shown that the linear neoclassical tearing mode is stabilized by the ion neoclassical viscosity in the banana regime even if Δ' > 0. (author)
Neoclassical transport optimization of LHD
Energy Technology Data Exchange (ETDEWEB)
Murakami, S.; Yamada, H.; Watanabe, K.Y. [National Inst. for Fusion Science, Toki, Gifu (Japan); Wakasa, A. [Hokkaido Univ., Graduate School of Engineering, Sapporo, Hokkaido (Japan); Maassberg, H.; Beidler, C.D. [Teilinstitut Greifswald, Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany)
2002-06-01
Neoclassical transport is studied for LHD configurations in which the magnetic axis has been shifted radially by determining the mono-energetic transport coefficient and the effective helical ripple. With respect to the transport in the long mean free path collisionality region - the so called 1/{nu} transport -, the optimum configuration is found when the magnetic axis has a major radius of 3.53m, which is 0.22m inward shifted from the standard'' configuration of LHD. In the optimized case, the effective helical ripple is very small, remaining below 2% inside 4/5 of the plasma radius. This indicates that a strong inward shift of the magnetic axis in the LHD can diminish the neoclassical transport to a level typical of so-called advanced stellarators''. (author)
Neoclassical transport optimization of LHD
International Nuclear Information System (INIS)
Murakami, S.; Yamada, H.; Watanabe, K.Y.; Wakasa, A.; Maassberg, H.; Beidler, C.D.
2002-06-01
Neoclassical transport is studied for LHD configurations in which the magnetic axis has been shifted radially by determining the mono-energetic transport coefficient and the effective helical ripple. With respect to the transport in the long mean free path collisionality region - the so called 1/ν transport -, the optimum configuration is found when the magnetic axis has a major radius of 3.53m, which is 0.22m inward shifted from the standard'' configuration of LHD. In the optimized case, the effective helical ripple is very small, remaining below 2% inside 4/5 of the plasma radius. This indicates that a strong inward shift of the magnetic axis in the LHD can diminish the neoclassical transport to a level typical of so-called advanced stellarators''. (author)
Turbulent momentum transport due to neoclassical flows
International Nuclear Information System (INIS)
Lee, Jungpyo; Barnes, Michael; Parra, Felix I; Belli, Emily; Candy, Jeff
2015-01-01
Intrinsic toroidal rotation in a tokamak can be driven by turbulent momentum transport due to neoclassical flow effects breaking a symmetry of turbulence. In this paper we categorize the contributions due to neoclassical effects to the turbulent momentum transport, and evaluate each contribution using gyrokinetic simulations. We find that the relative importance of each contribution changes with collisionality. For low collisionality, the dominant contributions come from neoclassical particle and parallel flows. For moderate collisionality, there are non-negligible contributions due to neoclassical poloidal electric field and poloidal gradients of density and temperature, which are not important for low collisionality. (paper)
Neoclassical MHD equilibria with ohmic current
International Nuclear Information System (INIS)
Tokuda, Shinji; Takeda, Tatsuoki; Okamoto, Masao.
1989-01-01
MHD equilibria of tokamak plasmas with neoclassical current effects (neoclassical conductivity and bootstrap current) were calculated self-consistently. Neoclassical effects on JFT-2M tokamak plasmas, sustained by ohmic currents, were studied. Bootstrap currents flow little for L-mode type equilibria because of low attainable values of poloidal beta, β J . H-mode type equilibria give bootstrap currents of 30% ohmic currents for β J attained by JFT-2M and 100% for β J ≥ 1.5, both of which are sufficient to change the current profiles and the resultant MHD equilibria. Neoclassical conductivity which has roughly half value of the classical Spitzer conductivity brings peaked ohmic current profiles to yield low safety factor at the magnetic axis. Neoclassical conductivity reduces the value of effective Z(Z eff ) which is necessary to give the observed one-turn voltage but it needs impurities accumulating at the center when such peaked current profiles are not observed. (author)
Neoclassical transport including collisional nonlinearity.
Candy, J; Belli, E A
2011-06-10
In the standard δf theory of neoclassical transport, the zeroth-order (Maxwellian) solution is obtained analytically via the solution of a nonlinear equation. The first-order correction δf is subsequently computed as the solution of a linear, inhomogeneous equation that includes the linearized Fokker-Planck collision operator. This equation admits analytic solutions only in extreme asymptotic limits (banana, plateau, Pfirsch-Schlüter), and so must be solved numerically for realistic plasma parameters. Recently, numerical codes have appeared which attempt to compute the total distribution f more accurately than in the standard ordering by retaining some nonlinear terms related to finite-orbit width, while simultaneously reusing some form of the linearized collision operator. In this work we show that higher-order corrections to the distribution function may be unphysical if collisional nonlinearities are ignored.
Is Teaching Neoclassical Economics as "the" Science of Economics Moral?
Parvin, Manoucher
1992-01-01
Discusses the morality of teaching neoclassical theory as the only science of economics. Argues that the teaching of neoclassical theory violates moral principles unless each and every attribute of neoclassical theory is proven superior to corresponding attributes of competing theories. Criticizes neoclassical economics for teaching what rather…
Neoclassical resonant transport of a mirror cell
International Nuclear Information System (INIS)
Ito, T.; Katanuma, I.
2005-01-01
The neoclassical resonant plateau transport in a mirror cell is studied theoretically. The analytical expression for a non-square-well magnetic field is obtained. The analytical result is applied to the GAMMA10 tandem mirror [T. Cho, M. Yoshida, J. Kohagura et al., Phys. Rev. Lett. 94, 085002-1 (2005)], which consists of several mirror cells in it, and the confinement time due to the neoclassical resonant plateau transport is determined in each mirror cell. It is found that the neoclassical resonant transport of ions trapped in the nonaxisymmetric anchor mirror cell and transition mirror cells is significantly smaller than those trapped in the central cell
Profit maximization mitigates competition
DEFF Research Database (Denmark)
Dierker, Egbert; Grodal, Birgit
1996-01-01
We consider oligopolistic markets in which the notion of shareholders' utility is well-defined and compare the Bertrand-Nash equilibria in case of utility maximization with those under the usual profit maximization hypothesis. Our main result states that profit maximization leads to less price...... competition than utility maximization. Since profit maximization tends to raise prices, it may be regarded as beneficial for the owners as a whole. Moreover, if profit maximization is a good proxy for utility maximization, then there is no need for a general equilibrium analysis that takes the distribution...... of profits among consumers fully into account and partial equilibrium analysis suffices...
Neoclassical MHD descriptions of tokamak plasmas
International Nuclear Information System (INIS)
Callen, J.D.; Kim, Y.B.; Sundaram, A.K.
1988-01-01
Considerable progress has been made in extending neoclassical MHD theory and in exploring the linear instabilities, nonlinear behavior and turbulence models it implies for tokamak plasmas. The areas highlighted in this paper include: extension of the neoclassical MHD equations to include temperature-gradient and heat flow effects; the free energy and entropy evolution implied by this more complete description; a proper ballooning mode formalism analysis of the linear instabilities; a new rippling mode type instability; numerical simulation of the linear instabilities which exhibit a smooth transition from resistive ballooning modes at high collisionality to neoclassical MHD modes at low collisionality; numerical simulation of the nonlinear growth of a single helicity tearing mode; and a Direct-Interaction-Approximation model of neoclassical MHD turbulence and the anomalous transport it induces which substantially improves upon previous mixing length model estimates. 34 refs., 2 figs
Nonlinear neoclassical transport in toroidal edge plasmas
International Nuclear Information System (INIS)
Fueloep, T.; Helander, P.
2001-01-01
In conventional neoclassical theory, the density and temperature gradients are not allowed to be as steep as frequently observed in the tokamak edge. In this paper the theory of neoclassical transport in a collisional, impure plasma is extended to allow for steeper profiles than normally assumed. The dynamics of highly charged impurity ions then becomes nonlinear, which affects the transport of all species. As earlier found in the banana regime, when the bulk plasma gradients are large the impurity ions undergo a poloidal redistribution, which reduces their parallel friction with the bulk ions and suppresses the neoclassical ion particle flux. The neoclassical confinement is thus improved in regions with large radial gradients. When the plasma is collisional and the gradients are large, the impurities accumulate on the inboard side of the torus
Studies of the neoclassical transport for CNT
International Nuclear Information System (INIS)
Seiwald, B; Nemov, V V; Pedersen, T Sunn; Kernbichler, W
2007-01-01
The original optimization of the Columbia Nonneutral Torus (CNT) considering only volume (and error field resilience) was also successful in optimizing the stored energy. To assess the general confinement properties of a device, studies of the 1/ν neoclassical transport (effective ripple ε eff ) are important. For CNT the field line tracing code NEO is used to compute ε eff . NEO is used by the code SORSSA for computation of the total stored energy based on neoclassical transport
Neoclassical tearing modes in a tokamak
International Nuclear Information System (INIS)
Hahm, T.S.
1988-08-01
Linear tearing instability is studied in the banana collisionality regime in tokamak geometry. Neoclassical effects produce significant modifications of Ohm's law and the vorticity equation so that the growth rate of tearing modes driven by Δ' is dramatically reduced compared to the usual resistive MHD value. Consequences of this result, regarding the presence of pressure-gradient-driven neoclassical resistive interchange instabilities and the evolution of magnetic islands in the Rutherford regime, are discussed. 10 refs
Gyrokinetic particle simulation of neoclassical transport
International Nuclear Information System (INIS)
Lin, Z.; Tang, W.M.; Lee, W.W.
1995-01-01
A time varying weighting (δf ) scheme for gyrokinetic particle simulation is applied to a steady-state, multispecies simulation of neoclassical transport. Accurate collision operators conserving momentum and energy are developed and implemented. Simulation results using these operators are found to agree very well with neoclassical theory. For example, it is dynamically demonstrated that like-particle collisions produce no particle flux and that the neoclassical fluxes are ambipolar for an ion--electron plasma. An important physics feature of the present scheme is the introduction of toroidal flow to the simulations. Simulation results are in agreement with the existing analytical neoclassical theory. The poloidal electric field associated with toroidal mass flow is found to enhance density gradient-driven electron particle flux and the bootstrap current while reducing temperature gradient-driven flux and current. Finally, neoclassical theory in steep gradient profile relevant to the edge regime is examined by taking into account finite banana width effects. In general, in the present work a valuable new capability for studying important aspects of neoclassical transport inaccessible by conventional analytical calculation processes is demonstrated. copyright 1995 American Institute of Physics
Neoclassical islands on COMPASS-D
International Nuclear Information System (INIS)
Gates, D.A.; Lloyd, B.; Morris, A.W.; McArdle, G.; O'Brien, M.R.; Valovic, M.; Warrick, C.D.; Wilson, H.R.
1997-01-01
Neoclassical magnetic islands are observed to limit the achievable β in COMPASS-D low collisionality single null divertor tokamak plasmas with ITER-like geometry (R 0 = 0.56 m, B 0 1.2 T, I p = 120-180 kA, κ = 1.6, ε = 0.3). The limiting β is typically well below that expected from ideal instabilities with maximum βN in the range of 1.6 to 2.1. The plasma is heated with up to 1.8 MW of 60 GHz electron cyclotron resonance heating (ECRH) at the second harmonic with X mode polarization. The time history of the measured island width is compared with the predictions of neoclassical tearing mode theory, with good agreement between theory and experiment. The measured islands have a threshold width below which the mode will not grow. The density scaling of the point of onset of the measured instabilities is compared with two theories that predict a threshold island width for the onset of neoclassical tearing modes. Applied resonant helical error fields are used to induce islands in collisionality regimes wherein the neoclassical islands do not occur naturally, allowing the study of the behaviour of neoclassical tearing modes in this regime. The critical β for the onset of neoclassical tearing modes is seen to be ∼3 times higher in the naturally stable region. This observation is compared with the predictions of both threshold theories. A simple expression for the q scaling of the maximum achievable β N in the presence of neoclassical tearing modes is derived on the basis of the assumption of a maximum allowable island width. The predicted q scaling of this β limit is compared with data from a q scan, and the results are in good agreement. (author)
Nonlinear neoclassical transport in toroidal edge plasmas
International Nuclear Information System (INIS)
Fueloep, T.
2002-01-01
Edge plasma processes play a critical role for the global confinement of the plasma in a tokamak. In the edge region, where impurity ions are abundant and the temperature and density gradients are large, the assumptions of standard neoclassical theory break down. This paper reviews recent extensions of neoclassical theory to treat this problem, in particular our own work, which focuses on the nonlinear aspects of transport in a plasma with heavy impurity ions. In this theory, the pressure and temperature gradients are allowed to be steeper than in conventional theory neoclassical theory, so that the friction force between the bulk ions and heavy impurities is comparable to the parallel impurity pressure gradient. The impurity ions are then found to undergo a spontaneous rearrangement on each flux surface. This reduces their parallel friction with the bulk ions and causes the neoclassical ion flux to become a non-monotonic function of the gradients for plasma parameters typical of the tokamak edge. Thus, the neoclassical confinement is improved in regions where the gradients are large, such as in the edge pedestal. (orig.)
On neoclassical impurity transport in stellarator geometry
International Nuclear Information System (INIS)
García-Regaña, J M; Kleiber, R; Beidler, C D; Turkin, Y; Maaßberg, H; Helander, P
2013-01-01
The impurity dynamics in stellarators has become an issue of moderate concern due to the inherent tendency of the impurities to accumulate in the core when the neoclassical ambipolar radial electric field points radially inwards (ion root regime). This accumulation can lead to collapse of the plasma due to radiative losses, and thus limit high performance plasma discharges in non-axisymmetric devices. A quantitative description of the neoclassical impurity transport is complicated by the breakdown of the assumption of small E × B drift and trapping due to the electrostatic potential variation on a flux surface Φ-tilde compared with those due to the magnetic field gradient. This work examines the impact of this potential variation on neoclassical impurity transport in the Large Helical Device heliotron. It shows that the neoclassical impurity transport can be strongly affected by Φ-tilde . The central numerical tool used is the δf particle in cell Monte Carlo code EUTERPE. The Φ-tilde used in the calculations is provided by the neoclassical code GSRAKE. The possibility of obtaining a more general Φ-tilde self-consistently with EUTERPE is also addressed and a preliminary calculation is presented. (paper)
ELEMENTS OF THE NEOCLASSICAL GROWTH THEORY
Directory of Open Access Journals (Sweden)
Florina Popa
2014-12-01
Full Text Available One of the relevant components of the contemporary economic science is the economic growth theory, the economic background of the time leading to new guidelines of the research. The neoclassical growth theory - the core of modern analysis - explains how the capital accumulation and technological changes affect the economy, significant for the analysis of the economic growth process being the Solow’s neoclassical growth model. The paper brief describes the elements of the economic growth model developed by Solow, both for the situation when it allows the explanation of extensive growth and that wherein the growth is of intensive nature, as a result of the intervention of exogenous technical progress – a determinant of factors productivity growth. It is highlighted the importance of the exogenous neoclassical model, proposed by Solow, who showed the determinant role of the technical progress in the economic growth phenomenon.
Moment equation approach to neoclassical transport theory
International Nuclear Information System (INIS)
Hirshman, S.P.
1978-01-01
The neoclassical cross-field fluxes for a toroidally confined, axisymmetric plasma are calculated in terms of the thermodynamic forces from the fluid continuity and momentum balance equations. This macroscopic formulation of neoclassical transport theory unifies the numerous complex expressions for the transport coefficients, previously obtained by solving the Fokker--Planck equation, and elucidates their physical basis. In the large aspect ratio limit, the continuous transition in the scaling of the diffusion coefficient throughout various collisionality regimes is shown to depend on the ratio of parallel viscosity coefficients of the plasma species. Comparison of the present results with the kinetic theory expressions for the neoclassical fluxes determines the parallel viscosity coefficients for a multispecies plasma in the long-mean-free-path regime
Neo-classical economics, institutional economics and improved fisheries management
van der Burg, Tsjalle
2000-01-01
According to neo-classical economists, taxes and individual transferable quotas (ITQs) are the most efficient measures for dealing with the problem of overfishing. Institutional economists, however, criticise neo-classical economists for neglecting political problems, enforcement problems and
The neoclassical theory of growth and distribution
Directory of Open Access Journals (Sweden)
Robert M. Solow
2000-12-01
Full Text Available The paper surveys the neoclassical theory of growth. As a preliminary, the meaning of the adjective "neoclassical" is discussed. The basic model is then sketched, and the conditions ensuring a stationary state are illustrated. The issue of the convergence to a stationary state (and that of the speed of convergence is further considered. A discussion of "primary factors" opens the way to the "new" theory of growth, with endogenous technical progress. A number of extensions of the basic model are then recalled: two-sector and multi-sectoral models, overlapping generations models, the role of money in growth models.
On the relation between neoclassical transport and turbulent transport
International Nuclear Information System (INIS)
Shaing, K.C.
2005-01-01
It is demonstrated through the flux-force relationship in the neoclassical theory that when neoclassical transport fluxes are improved, the damping rate of the radial electric field of the zonal flow is reduced. This, in turn, leads to improved turbulent transport fluxes. Thus, two seemingly unrelated transport fluxes are intimately connected through the momentum equation, and the neoclassical flux-force relation. This also implies a method to improve turbulent transport by improving neoclassical fluxes
Tri-maximal vs. bi-maximal neutrino mixing
International Nuclear Information System (INIS)
Scott, W.G
2000-01-01
It is argued that data from atmospheric and solar neutrino experiments point strongly to tri-maximal or bi-maximal lepton mixing. While ('optimised') bi-maximal mixing gives an excellent a posteriori fit to the data, tri-maximal mixing is an a priori hypothesis, which is not excluded, taking account of terrestrial matter effects
A critical approach to neoclassic monetarism
Directory of Open Access Journals (Sweden)
Yoandris Sierra Lara
2014-08-01
Full Text Available This article is aimed at assessing the current universal economic thought called Monetarism, especially in its neo-classic variant, represented by US economist Milton Friedman. The paper focuses on the analysis of the historical context that leads Monetarism to become a dominant doctrine, its main methodological features and the notions regarding inflation as a macroeconomic imbalance.
Nonlinear neoclassical theory for toroidal edge plasmas
International Nuclear Information System (INIS)
Fueloep, T.; Helander, P.
2001-01-01
Edge plasma processes play a critical role for the global confinement of the plasma. In the edge region, where impurity ions are abundant and the temperature and density gradients are large, the assumptions of the standard neoclassical theory break down. We have extended the theory of neoclassical transport in an impure plasma with arbitrary cross section and aspect ratio to allow for steeper pressure and temperature gradients than are usually considered in the conventional theory. The gradients are allowed to be so large that the friction force between the bulk ions and heavy impurities is comparable to the parallel impurity pressure gradient. In this case the impurity ions are found to undergo a spontaneous rearrangement on each flux surface. This reduces their parallel friction with the bulk ions and causes the neoclassical ion flux to become a non-monotonic function of the gradients for plasma parameters typical of the tokamak edge. Thus, the neoclassical confinement is improved in regions where the gradients are large, such as in the edge pedestal. The theoretical predictions are compared with experimental data from several tokamaks. (orig.)
Comparison of parallel viscosity with neoclassical theory
International Nuclear Information System (INIS)
Ida, K.; Nakajima, N.
1996-04-01
Toroidal rotation profiles are measured with charge exchange spectroscopy for the plasma heated with tangential NBI in CHS heliotron/torsatron device to estimate parallel viscosity. The parallel viscosity derived from the toroidal rotation velocity shows good agreement with the neoclassical parallel viscosity plus the perpendicular viscosity. (μ perpendicular = 2 m 2 /s). (author)
Electrical conductivity in tokamaks and extended neoclassical theory
International Nuclear Information System (INIS)
Segre, S.E.; Zanza, V.
1992-01-01
The electrical conductivity measurements reported from various tokamaks (D-III, PLT, TEXT, ASDEX, JT-60, TEXTOR, JET, TFTR) and compared with the usual neoclassical theory are here also compared with the extended neoclassical theory where the electron-electron collision rate is anomalous while the electron-ion collision rate remains Coulombian. It is found that, out of the 14 experiments considered, three are consistent with both the neoclassical and the extended neoclassical theories, four are consistent only with the extended neoclassical theory, and four are consistent with the neoclassical theory and also, within the experimental errors, not inconsistent with the extended neoclassical theory; the remaining three experiments appear to be incompatible with both theories. It is concluded that the extended neoclassical theory is in better agreement with conductivity experiments than the conventional neoclassical theory and, indeed, the extended theory is a serious candidate for explaining tokamak behaviour, since it accommodates naturally an anomalous electron thermal transport, which the conventional neoclassical theory is unable to do. (author). 31 refs, 1 fig
Kinetic neoclassical calculations of impurity radiation profiles
Directory of Open Access Journals (Sweden)
D.P. Stotler
2017-08-01
Full Text Available Modifications of the drift-kinetic transport code XGC0 to include the transport, ionization, and recombination of individual charge states, as well as the associated radiation, are described. The code is first applied to a simulation of an NSTX H-mode discharge with carbon impurity to demonstrate the approach to coronal equilibrium. The effects of neoclassical phenomena on the radiated power profile are examined sequentially through the activation of individual physics modules in the code. Orbit squeezing and the neoclassical inward pinch result in increased radiation for temperatures above a few hundred eV and changes to the ratios of charge state emissions at a given electron temperature. Analogous simulations with a neon impurity yield qualitatively similar results.
International Nuclear Information System (INIS)
Wakasa, Arimitsu; Oikawa, Shun-ichi; Murakami, Sadayoshi
2008-01-01
In helical systems, neoclassical transport is one of the important issues in addition to anomalous transport, because of a strong temperature dependency of heat conductivity and an important role in the radial electric field determination. Therefore, the development of a reliable tool for the neoclassical transport analysis is necessary for the transport analysis in Large Helical Device (LHD). We have developed a neoclassical transport database for LHD plasmas, DCOM/NNW, where mono-energetic diffusion coefficients are evaluated by the Monte Carlo method, and the diffusion coefficient database is constructed by a neural network technique. The input parameters of the database are the collision frequency, radial electric field, minor radius, and configuration parameters (R axis , beta value, etc). In this paper, database construction including the plasma beta is investigated. A relatively large Shafranov shift occurs in the finite beta LHD plasma, and the magnetic field configuration becomes complex leading to rapid increase in the number of the Fourier modes in Boozer coordinates. DCOM/NNW can evaluate neoclassical transport accurately even in such a configuration with a large number of Fourier modes. The developed DCOM/NNW database is applied to a finite-beta LHD plasma, and the plasma parameter dependences of neoclassical transport coefficients and the ambipolar radial electric field are investigated. (author)
Relativistic neoclassical transport coefficients with momentum correction
International Nuclear Information System (INIS)
Marushchenko, I.; Azarenkov, N.A.
2016-01-01
The parallel momentum correction technique is generalized for relativistic approach. It is required for proper calculation of the parallel neoclassical flows and, in particular, for the bootstrap current at fusion temperatures. It is shown that the obtained system of linear algebraic equations for parallel fluxes can be solved directly without calculation of the distribution function if the relativistic mono-energetic transport coefficients are already known. The first relativistic correction terms for Braginskii matrix coefficients are calculated.
Rotation and neoclassical ripple transport in ITER
Paul, E. J.; Landreman, M.; Poli, F. M.; Spong, D. A.; Smith, H. M.; Dorland, W.
2017-11-01
Neoclassical transport in the presence of non-axisymmetric magnetic fields causes a toroidal torque known as neoclassical toroidal viscosity (NTV). The toroidal symmetry of ITER will be broken by the finite number of toroidal field coils and by test blanket modules (TBMs). The addition of ferritic inserts (FIs) will decrease the magnitude of the toroidal field ripple. 3D magnetic equilibria in the presence of toroidal field ripple and ferromagnetic structures are calculated for an ITER steady-state scenario using the variational moments equilibrium code (VMEC). Neoclassical transport quantities in the presence of these error fields are calculated using the stellarator Fokker-Planck iterative neoclassical conservative solver (SFINCS). These calculations fully account for E r , flux surface shaping, multiple species, magnitude of ripple, and collisionality rather than applying approximate analytic NTV formulae. As NTV is a complicated nonlinear function of E r , we study its behavior over a plausible range of E r . We estimate the toroidal flow, and hence E r , using a semi-analytic turbulent intrinsic rotation model and NUBEAM calculations of neutral beam torque. The NTV from the \\vert{n}\\vert = 18 ripple dominates that from lower n perturbations of the TBMs. With the inclusion of FIs, the magnitude of NTV torque is reduced by about 75% near the edge. We present comparisons of several models of tangential magnetic drifts, finding appreciable differences only for superbanana-plateau transport at small E r . We find the scaling of calculated NTV torque with ripple magnitude to indicate that ripple-trapping may be a significant mechanism for NTV in ITER. The computed NTV torque without ferritic components is comparable in magnitude to the NBI and intrinsic turbulent torques and will likely damp rotation, but the NTV torque is significantly reduced by the planned ferritic inserts.
Gyrokinetic simulations of neoclassical transport using a minimal collision operator
International Nuclear Information System (INIS)
Dif-Pradalier, G.; Grandgirard, V.; Sarazin, Y.; Garbet, X.; Ghendrih, Ph.; Angelino, P.
2008-01-01
Conventional neoclassical predictions are successfully recovered within a gyrokinetic framework using a minimal Fokker-Planck collision operator. This operator is shown to accurately describe some essential features of neoclassical theory, namely the neoclassical transport, the poloidal rotation and the linear damping of axisymmetric flows while interestingly preserving a high numerical efficiency. Its form makes it especially adapted to Eulerian or Semi-Lagrangian schemes.
Neoclassical bootstrap current and transport in optimized stellarator configurations
International Nuclear Information System (INIS)
Maassberg, H.; Lotz, W.; Nuehrenberg, J.
1993-01-01
The neoclassical bootstrap current properties of optimized stellarators are analyzed in the relevant mean-free-path regimes and compared with the neoclassical transport properties. Two methods---global Monte Carlo simulation [Phys. Fluids 31, 2984 (1988)], and local analysis with the drift kinetic equation solver code [Phys. Fluids B 1, 563 (1989)]---are employed and good agreement is obtained. Full consistency with the elimination of the bootstrap current and favorable neoclassical transport are found
Effect of ion viscosity on neoclassical tearing mode
International Nuclear Information System (INIS)
Yoshida, Shigeki; Itoh, Sanae-I.; Yagi, Masatoshi; Azumi, Masafumi
2004-01-01
Linear stability analysis of neoclassical tearing mode (NTM) is performed on the basis of four-field reduced magnetohydrodynamic (MHD) model which takes account of fluctuating ion parallel flow and ion neoclassical viscosity. The dependence of the growth rate on the kinetic effects is investigated. It is shown that the linear NTM is stabilized by ion neoclassical viscosity and that the stabilizing effect of ion parallel compressibility is weak in the banana-plateau regime. It is found that not only ion neoclassical viscosity but also both ion and electron diamagnetic effects are important for the stabilization of NTM. (author)
Neoclassical versus Frontier Production Models ? Testing for the Skewness of Regression Residuals
DEFF Research Database (Denmark)
Kuosmanen, T; Fosgerau, Mogens
2009-01-01
The empirical literature on production and cost functions is divided into two strands. The neoclassical approach concentrates on model parameters, while the frontier approach decomposes the disturbance term to a symmetric noise term and a positively skewed inefficiency term. We propose a theoreti......The empirical literature on production and cost functions is divided into two strands. The neoclassical approach concentrates on model parameters, while the frontier approach decomposes the disturbance term to a symmetric noise term and a positively skewed inefficiency term. We propose...... a theoretical justification for the skewness of the inefficiency term, arguing that this skewness is the key testable hypothesis of the frontier approach. We propose to test the regression residuals for skewness in order to distinguish the two competing approaches. Our test builds directly upon the asymmetry...
Strong drifts effects on neoclassical transport
International Nuclear Information System (INIS)
Tessarotto, M.; Gregoratto, D.; White, R.B.
1996-01-01
It is well known that strong drifts play an important role in plasma equilibrium, stability and confinement A significant example concerns, in particular for tokamak plasmas, the case of strong toroidal differential rotation produced by E x B drift which is currently regarded as potentially important for its influence in equilibrium, stability and transport. In fact, theoretically, it has been found that shear flow can substantially affect the stability of microinstabilities as well modify substantially transport. Recent experimental observations of enhanced confinement and transport regimes in Tokamaks, show, however, evidence of the existence of strong drifts in the plasma core. These are produced not only by the radial electric field [which gives rise to the E x B drift], but also by density [N s ], temperature [T s ] and mass flow [V = ωRe var-phi , with e var-phi the toroidal unit vector, R the distance for the symmetry axis of the torus and ω being the toroidal angular rotation velocity] profiles which are suitably steep. This implies that, in a significant part of the plasma core, the relevant scale lengths of the gradients [of N s , T s , ω], i.e., respectively L N , L T and L ω can be as large as the radial scale length characterizing the banana orbits, L b . Interestingly enough, the transport estimates obtained appear close or even lower than the predictions based on the simplest neoclassical model. However, as is well known, the latter applies, in a strict sense only in the case of weak drifts and also ignoring even the contribution of shear flow related to strong E x B drift. Thus a fundamental problem appears the extension of neoclassical transport theory to include the effect of strong drifts in Tokamak confinement systems. The goal of this investigation is to develop a general formulation of neoclassical transport embodying such important feature
Experimental confirmation of neoclassical Compton scattering theory
Energy Technology Data Exchange (ETDEWEB)
Aristov, V. V., E-mail: aristov@iptm.ru [Russian Academy of Sciences, Institute of Microelectronics Technology and High Purity Materials (Russian Federation); Yakunin, S. N. [National Research Centre “Kurchatov Institute” (Russian Federation); Despotuli, A. A. [Russian Academy of Sciences, Institute of Microelectronics Technology and High Purity Materials (Russian Federation)
2013-12-15
Incoherent X-ray scattering spectra of diamond and silicon crystals recorded on the BESSY-2 electron storage ring have been analyzed. All spectral features are described well in terms of the neoclassical scattering theory without consideration for the hypotheses accepted in quantum electrodynamics. It is noted that the accepted tabular data on the intensity ratio between the Compton and Rayleigh spectral components may significantly differ from the experimental values. It is concluded that the development of the general theory (considering coherent scattering, incoherent scattering, and Bragg diffraction) must be continued.
How energy conversion drives economic growth far from the equilibrium of neoclassical economics
International Nuclear Information System (INIS)
Kümmel, Reiner; Lindenberger, Dietmar
2014-01-01
Energy conversion in the machines and information processors of the capital stock drives the growth of modern economies. This is exemplified for Germany, Japan, and the USA during the second half of the 20th century: econometric analyses reveal that the output elasticity, i.e. the economic weight, of energy is much larger than energy's share in total factor cost, while for labor just the opposite is true. This is at variance with mainstream economic theory according to which an economy should operate in the neoclassical equilibrium, where output elasticities equal factor cost shares. The standard derivation of the neoclassical equilibrium from the maximization of profit or of time-integrated utility disregards technological constraints. We show that the inclusion of these constraints in our nonlinear-optimization calculus results in equilibrium conditions, where generalized shadow prices destroy the equality of output elasticities and cost shares. Consequently, at the prices of capital, labor, and energy we have known so far, industrial economies have evolved far from the neoclassical equilibrium. This is illustrated by the example of the German industrial sector evolving on the mountain of factor costs before and during the first and the second oil price explosion. It indicates the influence of the ‘virtually binding’ technological constraints on entrepreneurial decisions, and the existence of ‘soft constraints’ as well. Implications for employment and future economic growth are discussed. (paper)
How energy conversion drives economic growth far from the equilibrium of neoclassical economics
Kümmel, Reiner; Lindenberger, Dietmar
2014-12-01
Energy conversion in the machines and information processors of the capital stock drives the growth of modern economies. This is exemplified for Germany, Japan, and the USA during the second half of the 20th century: econometric analyses reveal that the output elasticity, i.e. the economic weight, of energy is much larger than energy's share in total factor cost, while for labor just the opposite is true. This is at variance with mainstream economic theory according to which an economy should operate in the neoclassical equilibrium, where output elasticities equal factor cost shares. The standard derivation of the neoclassical equilibrium from the maximization of profit or of time-integrated utility disregards technological constraints. We show that the inclusion of these constraints in our nonlinear-optimization calculus results in equilibrium conditions, where generalized shadow prices destroy the equality of output elasticities and cost shares. Consequently, at the prices of capital, labor, and energy we have known so far, industrial economies have evolved far from the neoclassical equilibrium. This is illustrated by the example of the German industrial sector evolving on the mountain of factor costs before and during the first and the second oil price explosion. It indicates the influence of the ‘virtually binding’ technological constraints on entrepreneurial decisions, and the existence of ‘soft constraints’ as well. Implications for employment and future economic growth are discussed.
The turn in economics: neoclassical dominance to mainstream pluralism?
Davis, J.B.
2006-01-01
This paper investigates whether since the 1980s neoclassical economics has been in the process of being supplanted as the dominant research programme in economics by a collection of competing research approaches which share relatively little in common with each other or with neoclassical economics.
Neoclassical electron heat conduction in tokamaks performed by the ions
International Nuclear Information System (INIS)
Ware, A.A.
1987-07-01
The increment to neoclassical ion heat conduction caused by electron collisions is shown to act like electron heat conduction since the energy is taken from and given back to the electrons at each diffusion step length. It can exceed electron neoclassical heat conduction by an order of magnitude
Neoclassical compounds and final combining forms in English
Directory of Open Access Journals (Sweden)
Ana Díaz-Negrillo
2014-12-01
Full Text Available English neoclassical compounds rely on a distinct vocabulary stock and present morphological features which raise a number of theoretical questions. Generalisations about neoclassical compounds are also problematic because the output is by no means homogeneous, that is, defining features of neoclassical compounds sometimes co-exist with features that are not prototypical of these formations. The paper looks at neoclassical compounds with a view to exploring patterns of morphological behaviour and development in this class of compounds. The approach is both synchronic and diachronic: it researches whether the morphological behaviour of recently formed compounds is different from that of earlier compounds and, if so, in which respects. This is assessed on data from the BNC with respect to some of the features that are cited in the literature as defining properties of neoclassical compounds, specifically, their internal configuration, the occurrence or not of a linking vowel, and their productivity.
Neoclassical rotation velocities in multispecies plasmas
International Nuclear Information System (INIS)
Houlberg, W.A.; Hirshman, S.P.; Shaing, K.C.
1996-01-01
We examine the relationships between the poloidal, toroidal and parallel rotation velocities for typical plasma conditions in existing tokamak experiments. The radial force balance, neoclassical solution to the poloidal flow from the parallel force balance, and anomalous toroidal rotation axe included. A full multispecies formulation of the neoclassical transport theory is implemented in the NCLASS code (which includes arbitrary axisymmetric geometries and plasma collisionalities) to determine the poloidal rotation velocities. Comparisons are made with analytic relationships derived from a single impurity formulation of the problem. The roles of the radial electric field and species density and pressure gradients are evaluated. The determination of the radial electric field using the NCLASS solution for poloidal rotation and a local measurement of the toroidal rotation in conjunction with measured plasma profiles is discussed; it has been used in analysis of TFTR enhanced reverse shear plasmas. The ordering of banana orbit size small relative to local minor radius and gradients (as incorporated into initial versions of NCLASS) are examined for typical negative shear plasmas. We show the degree to which these constraints axe violated and demonstrate that finite orbit corrections axe required for better determination of the bootstrap current, particle fluxes and ion heat fluxes, i.e., the conditions r much-lt Δ b much-lt r n , r T , r E are significantly violated. Progress in relaxing these constraints is discussed
Neo-classical theory of competition or Adam Smith's hand as mathematized ideology
McCauley, Joseph L.
2001-10-01
Orthodox economic theory (utility maximization, rational agents, efficient markets in equilibrium) is based on arbitrarily postulated, nonempiric notions. The disagreement between economic reality and a key feature of neo-classical economic theory was criticized empirically by Osborne. I show that the orthodox theory is internally self-inconsistent for the very reason suggested by Osborne: lack of invertibility of demand and supply as functions of price to obtain price as functions of supply and demand. The reason for the noninvertibililty arises from nonintegrable excess demand dynamics, a feature of their theory completely ignored by economists.
Neoclassical diffusion at low L-shel
Cunningham, G.; Ripoll, J. F.; Loridan, V.; Schulz, M.
2017-12-01
At very low L-shell, the lifetime of MeV electrons is dominated by pitch-angle scattering due to Coulomb collisions with background neutrals and ions. Walt's evaluation of this lifetime explained Van Allen's observations of the decay of the radiation belts in the early 1960's, for L500 keV electrons for L=[1.15,1.21] was much greater than predicted by Walt's model when the decay was observed over 3 years rather than just a few months. Imhof et al argued that inward radial diffusion from larger L would be a source of electrons at low L, thus increasing the apparent lifetimes that were observed, but did not speculate on the cause of such diffusion across L. Newkirk and Walt estimated the radial diffusion coefficient that would be needed to explain the apparent lifetimes observed by Imhof et al. The radial diffusion coefficients they inferred dropped sharply as L increased, contrasting with the radial diffusion coefficients that had been recently developed by Falthammar [1965], which increase as a power law in L. Newkirk and Walt noted Falthammar's speculation that pitch-angle diffusion caused by Coulomb scattering, when coupled to drift-shell splitting associated with non-dipolar terms in the near-Earth geomagnetic field, might be the physical basis for the radial diffusion, but they did not attempt to quantify this effect. Roederer et al demonstrated that Coulomb scattering plus drift-shell splitting could explain the Newkirk and Walt results but they did not perform an exhaustive study. In the field of magnetically confined fusion, the movement of charged particles to different drift-shells caused by the combination of collisions and drift-shell splitting is labeled `neoclassical' diffusion. By contrast, `anomalous' diffusion results from pitch-angle diffusion caused by wave turbulence combined with drift-shell splitting, an effect recently studied by O'Brien in the outer radiation belt. We have constructed a comprehensive model of neoclassical diffusion at low L
Geometrical influences on neoclassical magnetohydrodynamic tearing modes
International Nuclear Information System (INIS)
Kruger, S.E.; Hegna, C.C.; Callen, J.D.
1997-07-01
The influence of geometry on the pressure drives of nonideal magnetohydrodynamic tearing modes is presented. In order to study the effects of elongation, triangularity, and aspect ratio, three different machines are considered to provide a range of tokamak configurations: TFTR (circular), DIII-D (D-shaped), and Pegasus (extremely low aspect ratio). For large aspect ratio tokamaks, shaping does very little to influence the pressure gradient drives, while at low aspect ratios, a very strong sensitivity to the profiles is found. In particular, this sensitivity is connected to the strong dependence on the magnetic shear. This suggests that at low aspect ratio it may be possible to stabilize neoclassical tearing modes by flattening the q profile near low order rational surfaces (e.g., q = 2/1) using a combination of shaping and localized current drive, whereas at large aspect ratio it is more difficult
Mode coupling trigger of neoclassical magnetohydrodynamic tearing modes in tokamaks
International Nuclear Information System (INIS)
Gianakon, T.A.; Hegna, C.C.; Callen, J.D.
1997-05-01
Numerical studies of the nonlinear evolution of coupled magnetohydrodynamic - type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion of neoclassical physics introduces an additional free-energy source for the nonlinear formation of magnetic islands through the effects of a bootstrap current in Ohm's law. The neoclassical tearing mode is demonstrated to be destabilized in plasmas which are otherwise Δ' stable, albeit once a threshold island width is exceeded. A possible mechanism for exceeding or eliminating this threshold condition is demonstrated based on mode coupling due to toroidicity with a pre-existing instability at the q = 1 surface
Revisited neoclassical transport theory for steep, collisional plasma edge profiles
International Nuclear Information System (INIS)
Rogister, A.L.
1994-01-01
Published neoclassical results are misleading as concerns the plasma edge for they do not adequately take the peculiar local conditions into account, in particular the fact that the density and temperature variation length-scales are quite small. Coupled novel neoclassical equations obtain, not only for the evolution of the density and temperatures, but also for the radial electric field and the evolution of the parallel ion momentum: gyro-stresses and inertia indeed upset the otherwise de facto ambipolarity of particle transport and a radial electric field necessarily builds up. The increased nonlinear character of these revisited neoclassical equations widens the realm of possible plasma behaviors. (author)
Neoclassical transport and radial electric fields in TJ-K
International Nuclear Information System (INIS)
Rahbarnia, K.; Greiner, F.; Ramisch, M.; Stroth, U.; Greiner, F.
2003-01-01
The neoclassical transport is investigated in the torsatron TJ-K, which is operated with a low-temperature plasma. In the low-collisionality regime neoclassical losses are not intrinsically ambipolar, leading to the formation of a radial electric field which acts on both neoclassical and turbulent transport. This electric field is measured with a combination of Langmuir and emissive probes. The data are compared with the ambipolar electric field calculated with an analytic model. The experimental fields are positive and larger than the calculated ones. Direct losses of the fast electrons might explain this discrepancy. (orig.)
Indian Academy of Sciences (India)
Abstract. It is shown that (i) every probability density is the unique maximizer of relative entropy in an appropriate class and (ii) in the class of all pdf f that satisfy. ∫ fhi dμ = λi for i = 1, 2,...,...k the maximizer of entropy is an f0 that is pro- portional to exp(. ∑ ci hi ) for some choice of ci . An extension of this to a continuum of.
Indian Academy of Sciences (India)
It is shown that (i) every probability density is the unique maximizer of relative entropy in an appropriate class and (ii) in the class of all pdf that satisfy ∫ f h i d = i for i = 1 , 2 , … , … k the maximizer of entropy is an f 0 that is proportional to exp ( ∑ c i h i ) for some choice of c i . An extension of this to a continuum of ...
SCIENCE WHERE CULTURE MATTERS: A NEO-CLASSICAL ...
Indian Academy of Sciences (India)
SCIENCE WHERE CULTURE MATTERS: A NEO-CLASSICAL APPROACH TO EXPLORE UNTAPPED BACTERIAL DIVERSITY. MILIND WATVE; Dept of Microbiology, Abasaheb Garware College, Pune. www.culturematters.org; * Life Research Foundation, Pune; * Evolvus Biotech Pvt. Ltd.,Pune ...
Can Neoclassical Economics Underpin the Reform of Centrally Planned Economies?
Peter Murrell
1991-01-01
This paper addresses whether neoclassical economics can provide the intellectual underpinning for a theory of reform. I examine whether the neoclassical model satisfies an essential condition to qualify for this role: does it give us a satisfactory explanation for the vast differences in performance between capitalist and socialist economic systems? First, I focus on the theoretical arguments that have traditionally been used to examine the comparative properties of central planning and marke...
Breakdown of Onsager symmetry in neoclassical transport theory
International Nuclear Information System (INIS)
Molvig, K.; Bernstein, I.B.
1982-01-01
Neoclassical transport theory is developed in a Lagrangian rather than the usual Eulerian formulation.. It is shown that an underlying asymmetry exists in the neoclassical pinch and bootstrap effects and demonstrate the physical basis of the Onsager symmetry relationship in the pinch-bootstrap duality. A simple model calculation shows that low frequency turbulence can destroy the bootstrap current at levels, ephi-circumflex/Tsub(c) approximately 10 -2 , too low to affect the Ware pinch. (author)
Are neoclassical canons valid for southern Chinese faces?
Directory of Open Access Journals (Sweden)
Yasas S N Jayaratne
Full Text Available BACKGROUND: Proportions derived from neoclassical canons, initially described by Renaissance sculptors and painters, are still being employed as aesthetic guidelines during the clinical assessment of the facial morphology. OBJECTIVE: 1. to determine the applicability of neoclassical canons for Southern Chinese faces and 2. to explore gender differences in relation to the applicability of the neoclassical canons and their variants. METHODOLOGY: 3-D photographs acquired from 103 young adults (51 males and 52 females without facial dysmorphology were used to test applicability of four neoclassical canons. Standard anthropometric measurements that determine the facial canons were made on these 3-D images. The validity of the canons as well as their different variants were quantified. PRINCIPAL FINDINGS: The neoclassical cannons seldom applied to these individuals, and facial three-section and orbital canons did not apply at all. The orbitonasal canon was most frequently applicable, with a frequency of 19%. Significant sexual dimorphism was found relative to the prevalence of the variants of facial three-section and orbitonasal canons. CONCLUSION: The neoclassical canons did not appear to apply to our sample when rigorous quantitative measurements were employed. Thus, they should not be used as esthetic goals for craniofacial surgical interventions.
Nonlinear dynamics of single-helicity neoclassical MHD tearing instabilities
International Nuclear Information System (INIS)
Spong, D.A.; Shaing, K.C.; Carreras, B.A.; Callen, J.D.; Garcia, L.
1988-10-01
Neoclassical magnetohydrodynamic (MHD) effects can significantly alter the nonlinear evolution of resistive tearing instabilities. This is studied numerically by using a flux-surface-averaged set of evolution equations that includes the lowest-order neoclassical MHD effects. The new terms in the equations are fluctuating bootstrap current, neoclassical modification of the resistivity, and neoclassical damping of the vorticity. Single-helicity tearing modes are studied in a cylindrical model over a range of neoclassical viscosities (μ/sub e//ν/sup e/) and values of the Δ' parameter of tearing mode theory. Increasing the neoclassical viscosity leads to increased growth rate and saturated island width as predicted analytically. The larger island width is caused by the fluctuating bootstrap current contribution in Ohm's law. The Δ' parameter no longer solely determines the island width, and finite-width saturated islands may be obtained even when Δ' is negative. The importance of the bootstrap current (/approximately/∂/rho///partial derivative/psi/) in the nonlinear dynamics leads us to examine the sensitivity of the results with respect to different models for the density evolution. 11 refs., 8 figs
Neoclassical transport of impurtities in tokamak plasmas
International Nuclear Information System (INIS)
Hirshman, S.P.; Sigmar, D.J.
1981-05-01
Tokamak plasmas are inherently comprised of multiple ion species. This is due to wall-bred impurities and, in future reactors, will result from fusion-born alpha particles. Relatively small concentrations of highly charged non-hydrogenic impurities can strongly influence plasma transport properties whenever n/sub I/e/sub I/ 2 /n/sub H/e 2 greater than or equal to (m/sub e//m/sub H/)/sup 1/2/. The determination of the complete neoclassical Onsager matrix for a toroidally confined multispecies plasma, which provides the linear relation between the surface averaged radial fluxes and the thermodynamic forces (i.e., gradients of density and temperature, and the parallel electric field), is reviewed. A closed set of one-dimensional moment equations is presented for the time evolution of thermodynamic and magnetic field quantities which results from collisional transport of the plasma and two dimensional motion of the magnetic flux surface geometry. The effects of neutral beam injection on the equilibrium and transport properties of a toroidal plasma are consistently included
Linear neoclassical tearing mode in tokamaks
International Nuclear Information System (INIS)
Shaing, K. C.
2007-01-01
The growth rate of linear tearing modes in tokamaks is calculated including the neoclassical dissipation mechanism. It is found that when the growth rate is much smaller than the ion-ion collision frequency, the growth rate is reduced approximately by a factor of (B p /B) 2/5 from its standard value, and when the growth rate is much larger than the ion-ion collision frequency, the growth rate is reduced by a factor [√(ε)/(1.6q 2 )] 1/5 . Here, B p is the poloidal magnetic field strength, B is the magnetic field strength, ε is the inverse aspect ratio, and q is the safety factor. The width of the resistive layer is broadened when compared to that of the standard theory. In both limits, the growth rate and the resistive layer width only depend on B p and are independent of B. The growth rates in the plateau regime and for the inertia dominant modes are also presented
Neoclassical poloidal and toroidal rotation in tokamaks
International Nuclear Information System (INIS)
Kim, Y.B.; Diamond, P.H.; Groebner, R.J.
1991-01-01
Explicit expressions for the neoclassical poloidal and toroidal rotation speeds of primary ion and impurity species are derived via the Hirshman and Sigmar moment approach. The rotation speeds of the primary ion can be significantly different from those of impurities in various interesting cases. The rapid increase of impurity poloidal rotation in the edge region of H-mode discharges in tokamaks can be explained by a rapid steepening of the primary ion pressure gradient. Depending on ion collisionality, the poloidal rotation speed of the primary ions at the edge can be quite small and the flow direction may be opposite to that of the impurities. This may cast considerable doubts on current L to H bifurcation models based on primary ion poloidal rotation only. Also, the difference between the toroidal rotation velocities of primary ions and impurities is not negligible in various cases. In Ohmic plasmas, the parallel electric field induces a large impurity toroidal rotation close to the magnetic axis, which seems to agree with experimental observations. In the ion banana and plateau regime, there can be non-negligible disparities between primary ion and impurity toroidal rotation velocities due to the ion density and temperature gradients. Detailed analytic expressions for the primary ion and impurity rotation speeds are presented, and the methodology for generalization to the case of several impurity species is also presented for future numerical evaluation
Density control problems in large stellarators with neoclassical transport
International Nuclear Information System (INIS)
Maassberg, H.; Beidler, C.D.; Simmet, E.E.
1999-01-01
With respect to the particle flux, the off-diagonal term in the neoclassical transport matrix becomes crucial in the stellarator long-mean-free-path regime. Central heating with peaked temperature profiles can make an active density profile control by central particle refuelling mandatory. The neoclassical particle confinement can significantly exceed the energy confinement at the outer radii. As a consequence, the required central refuelling may be larger than the neoclassical particle fluxes at outer radii leading to the loss of the global density control. Radiative losses as well as additional 'anomalous' electron heat diffusivities further exacerbate this problem. In addition to the analytical formulation of the neoclassical link of particle and energy fluxes, simplified model simulations as well as time-dependent ASTRA code simulations are described. In particular, the 'low-' and 'high-mirror' W7-X configurations are compared. For the W7-X 'high-mirror' configuration especially, the appearance of the neoclassical particle transport barrier is predicted at higher densities. (author)
Neoclassical Simulation of Tokamak Plasmas using Continuum Gyrokinetc Code TEMPEST
International Nuclear Information System (INIS)
Xu, X Q
2007-01-01
We present gyrokinetic neoclassical simulations of tokamak plasmas with self-consistent electric field for the first time using a fully nonlinear (full-f) continuum code TEMPEST in a circular geometry. A set of gyrokinetic equations are discretized on a five dimensional computational grid in phase space. The present implementation is a Method of Lines approach where the phase-space derivatives are discretized with finite differences and implicit backwards differencing formulas are used to advance the system in time. The fully nonlinear Boltzmann model is used for electrons. The neoclassical electric field is obtained by solving gyrokinetic Poisson equation with self-consistent poloidal variation. With our 4D (ψ, θ, ε, μ) version of the TEMPEST code we compute radial particle and heat flux, the Geodesic-Acoustic Mode (GAM), and the development of neoclassical electric field, which we compare with neoclassical theory with a Lorentz collision model. The present work provides a numerical scheme and a new capability for self-consistently studying important aspects of neoclassical transport and rotations in toroidal magnetic fusion devices
Low Z impurity transport in tokamaks. [Neoclassical transport theory
Energy Technology Data Exchange (ETDEWEB)
Hawryluk, R.J.; Suckewer, S.; Hirshman, S.P.
1978-10-01
Low Z impurity transport in tokamaks was simulated with a one-dimensional impurity transport model including both neoclassical and anomalous transport. The neoclassical fluxes are due to collisions between the background plasma and impurity ions as well as collisions between the various ionization states. The evaluation of the neoclassical fluxes takes into account the different collisionality regimes of the background plasma and the impurity ions. A limiter scrapeoff model is used to define the boundary conditions for the impurity ions in the plasma periphery. In order to account for the spectroscopic measurements of power radiated by the lower ionization states, fluxes due to anomalous transport are included. The sensitivity of the results to uncertainties in rate coefficients and plasma parameters in the periphery are investigated. The implications of the transport model for spectroscopic evaluation of impurity concentrations, impurity fluxes, and radiated power from line emission measurements are discussed.
UNCERTAINTY IN NEOCLASSICAL AND KEYNESIAN THEORETICAL APPROACHES: A BEHAVIOURAL PERSPECTIVE
Directory of Open Access Journals (Sweden)
Sinziana BALTATESCU
2015-11-01
Full Text Available The ”mainstream” neoclassical assumptions about human economic behavior are currently challenged by both behavioural researches on human behaviour and other theoretical approaches which, in the context of the recent economic and financial crisis find arguments to reinforce their theoretical statements. The neoclassical “perfect rationality” assumption is most criticized and provokes the mainstream theoretical approach to efforts of revisiting the theoretical framework in order to re-state the economic models validity. Uncertainty seems, in this context, to be the concept that allows other theoretical approaches to take into consideration a more realistic individual from the psychological perspective. This paper is trying to present a comparison between the neoclassical and Keynesian approach of the uncertainty, considering the behavioural arguments and challenges addressed to the mainstream theory.
Neoclassical kinetic theory near an X point: Plateau regime
International Nuclear Information System (INIS)
Solano, E.R.; Hazeltine, R.D.
1994-01-01
Traditionally, neoclassical transport calculations ignore poloidal variation of the poloidal magnetic field. Near an X point of the confining field of a diverted plasma, the poloidal field is small, causing guiding centers to linger at that poloidal position. A study of how neoclassical transport is affected by this differential shaping is presented. The problem is solved in general in the plateau regime, and a model poloidal flux function with an X point is utilized as an analytic example to show that the plateau diffusion coefficient can change considerably (factor of 2 reduction). Ion poloidal rotation is proportional to the local value of B pol but otherwise it is not strongly affected by shaping. The usual favorable scaling of neoclassical confinement time with plasma current is unaffected by the X point
Neoclassical current and plasma rotation in helical systems
International Nuclear Information System (INIS)
Nakajima, N.; Okamoto, M.
1991-01-01
In order to clarify geometrical effects of the magnetic field on the neoclassical theory in general toroidal systems, the neoclassical parallel particle flow, heat flux, current and plasma rotation of a multispecies plasma are examined using the moment approach on the basis of the original papers under the assumptions of no fluctuations, no external sources and losses except for a fast ion beam and an external inductive electric field, steady state, and |u a | Ta where u a and v Ta are the macro and thermal velocity of species a, respectively. Hence, we might have a point of view of unifying understanding the neoclassical theory in general toroidal systems. Three collisionality regimes, i.e., the 1/ν (in non-axisymmetric toroidal systems) or banana (in axisymmetric toroidal systems), plateau, and Pfirsch-Schlueter collisionality regimes are examined separately. (author) 8 refs
Neoclassical dissipation and resistive wall modes in tokamaks
International Nuclear Information System (INIS)
Shaing, K.C.
2004-01-01
It is shown that the critical toroidal plasma flow speed that is required to stabilize the resistive wall mode in tokamaks is reduced by a factor of the order of B/B θ or of 1.265ε 3sol4 B/B θ depending on the plasma parameters when the perturbed neoclassical viscosity driven current is taken into account. Here, B is the magnetic field strength, B θ is the poloidal magnetic field strength, and ε is the inverse aspect ratio. This effect is illustrated using an existing model for the resistive wall modes by including the neoclassical dissipation in the derivation of the dispersion relation. The derivation is based on fluid equations with the plasma viscosity, calculated using kinetic equation, as the closure. The reduction of the critical toroidal speed is a consequence of the parallel (to the magnetic field B) momentum equation when neoclassical viscosity becomes important. The results are compared with experimental observations in tokamaks
Effect of sheared flows on neoclassical tearing modes
Energy Technology Data Exchange (ETDEWEB)
Sen, A [Institute for Plasma Research, Bhat, Gandhinagar (India); Chandra, D; Kaw, P [Institute for Plasma Research, Bhat, Gandhinagar (India); Bora, M P [Physics Dept., Gauhati University, Guwahati (India); Kruger, S [Tech-X, Boulder, CO (United States); Ramos, J [Plasma Science and Fusion Center, MIT, Cambridge, MA (United States)
2005-01-01
The influence of toroidal sheared equilibrium flows on the nonlinear evolution of classical and neoclassical tearing modes (NTMs) is studied through numerical solutions of a set of reduced generalized MHD equations that include viscous force effects based on neoclassical closures. In general, differential flow is found to have a strong stabilizing influence leading to lower saturated island widths for the classical (m/n = 2/1) mode and reduced growth rates for the (m/n = 3/1) neoclassical mode. Velocity shear on the other hand is seen to make a destabilizing contribution. An analytic model calculation, consisting of a generalized Rutherford island evolution equation that includes shear flow effects is also presented and the numerical results are discussed in the context of this model. (author)
The status of -o- or on the allomorphy of neo-classical compounds
Hamans, C.; de la Cruz Cabanillas, I.; Tejedor Martínez, C.
2014-01-01
This paper aims at solving an old descriptive problem in dealing with neoclassical compounds: the status of the segment -o- which usually appears between the two elements of neoclassical compounds as in hamburgerology, buyology, bacteriology and epidemiology.
Curvature effect on tearing modes in presence of neoclassical friction
Energy Technology Data Exchange (ETDEWEB)
Maget, Patrick; Mellet, Nicolas; Meshcheriakov, Dmytro; Garbet, Xavier [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France); Lütjens, Hinrich [Centre de Physique Théorique, Ecole Polytechnique, CNRS (France)
2013-11-15
Neoclassical physics (here associated to the poloidal variation of the magnetic field strength along field lines in a tokamak) is well known for driving self-generated plasma current and nonlinear magnetic islands associated to it in high performance, ITER relevant plasma discharges. It is demonstrated that the neoclassical friction between a magnetic perturbation and plasma flow already impacts magnetic islands in the linear regime, by inducing a weakening of curvature stabilization for tearing modes. This conclusion holds in particular for regimes where convection is influencing the pressure dynamics, as shown using a simple analytical model and confirmed in full Magneto-Hydro-Dynamics simulations.
From current-driven to neoclassically driven tearing modes.
Reimerdes, H; Sauter, O; Goodman, T; Pochelon, A
2002-03-11
In the TCV tokamak, the m/n = 2/1 island is observed in low-density discharges with central electron-cyclotron current drive. The evolution of its width has two distinct growth phases, one of which can be linked to a "conventional" tearing mode driven unstable by the current profile and the other to a neoclassical tearing mode driven by a perturbation of the bootstrap current. The TCV results provide the first clear observation of such a destabilization mechanism and reconcile the theory of conventional and neoclassical tearing modes, which differ only in the dominant driving term.
Stationary neoclassical profiles of plasma parameters in stellarators
International Nuclear Information System (INIS)
Danilkin, I.S.; Mineev, A.B.
1991-01-01
Peculiarities of neoclassical model of heat and particle transfer, occuring by calculations of plasma stationary profile parameters in stellarators are considered. The main peculiarity out of all consists in ineadequate compatibility with real physical conditions on the boundary, requiring application of supplementary 'anomalous' transfer or special (but technically possible) adjustment of particle and heat sources to achieve solution in form of 'correct' monotonically sloping profile. It is stated, that neoclassical theory does not provide for well-known ambiguity of solutions for ambipolar electrical field by search of monotonous stationary profiles supported by outside sources
Kinetic energy principle and neoclassical toroidal torque in tokamaks
International Nuclear Information System (INIS)
Park, Jong-Kyu
2011-01-01
It is shown that when tokamaks are perturbed, the kinetic energy principle is closely related to the neoclassical toroidal torque by the action invariance of particles. Especially when tokamaks are perturbed from scalar pressure equilibria, the imaginary part of the potential energy in the kinetic energy principle is equivalent to the toroidal torque by the neoclassical toroidal viscosity. A unified description therefore should be made for both physics. It is also shown in this case that the potential energy operator can be self-adjoint and thus the stability calculation can be simplified by minimizing the potential energy.
Stationary neoclassical profiles of plasma parameters in stellarators
International Nuclear Information System (INIS)
Danilkin, I.S.; Mineev, A.B.
1991-01-01
The properties of the neoclassical model of heat and particle transport are considered in connection with calculations of stationary profiles of the plasma parameters in stellarators. The most important feature is the poor agreement with real physical conditions of the boundary, which imposes the necessity of invoking either an additional anomalous transport or a special (although technically possible) consistency between the particle and heat sources in order to obtain a solution in the form of a correct monotonically decreasing profile. In search for monotonic stationary profiles maintained by external sources, it is ascertained that the neoclassical theory does not give rise to the well-known multivalued solutions for the ambipolar electric field
Asymmetry of neoclassical transport by dipole electric field
International Nuclear Information System (INIS)
Wang Zhongtian; Wang Long
2004-01-01
Effects of dipole electric fields on neoclassical transport are studied. Large asymmetry in transport is created. The dipole fields, which are in a negative R-direction, reduce the ion drift, increase electron drift, and change the steps of excursion due to collisions. It is found that different levels of dipole field intensities have different types of transport. For the lowest level of the dipole field, the transport returns to the neoclassical one. For the highest level of the dipole field, the transport is turned to be the turbulence transport similar to the pseudo-classical transport. Experimental data may be corresponded to a large level of the dipole field intensity. (authors)
SCIENCE WHERE CULTURE MATTERS: A NEO-CLASSICAL ...
Indian Academy of Sciences (India)
Table of contents. SCIENCE WHERE CULTURE MATTERS: A NEO-CLASSICAL APPROACH TO EXPLORE UNTAPPED BACTERIAL DIVERSITY · UNDER GRADUATE RESEARCH An alternative model of doing science · THE EXPANSE OF LIFE · HOW MANY SP. OF BACTERIA IN 1 g SOIL? TORSVIK ET AL 1990.
Numerical study of neoclassical plasma pedestal in a tokamak geometry
International Nuclear Information System (INIS)
Chang, C.S.; Ku, Seunghoe; Weitzner, H.
2004-01-01
The fundamental properties of steep neoclassical plasma pedestals in a quiescent tokamak plasma have been investigated with a new guiding center particle code XGC: an X-point included Guiding Center code. It is shown that the width of the steepest neoclassical pedestals is similar to an experimentally observed edge pedestal width, and that a steep pedestal must be accompanied by a self-consistent negative radial electric field well. It is also shown that a steep neoclassical pedestal can form naturally at a quiescent diverted edge as the particle source from the neutral penetration (and heat flux from the core plasma) is balanced by the sharply increasing convective ion loss toward the separatrix. The steep neoclassical pedestal and the strong radial electric field well are suppressed by an anomalous diffusion coefficient of a strength appropriate to an L-mode state; nonetheless, the ExB shearing rate increases rapidly with pedestal temperature. Additionally, the present study shows that a steep pedestal at the diverted edge acts as a cocurrent parallel momentum source
Chaotic neoclassical separatrix dissipation in parametric drift-wave decay.
Kabantsev, A A; Tsidulko, Yu A; Driscoll, C F
2014-02-07
Experiments and theory characterize a parametric decay instability between plasma drift waves when the nonlinear coupling is modified by an electrostatic barrier. Novel mode coupling terms representing enhanced dissipation and mode phase shifts are caused by chaotic separatrix crossings on the wave-ruffled separatrix. Experimental determination of these coupling terms is in broad agreement with new chaotic neoclassical transport analyses.
Testing Neoclassical Competitive Theory in Multilateral Decentralized Markets
List, John A.
2004-01-01
Walrasian tatonnement has been a fundamental assumption in economics ever since Walras' general equilibrium theory was introduced in 1874. Nearly a century after its introduction, Vernon Smith relaxed the Walrasian tatonnement assumption by showing that neoclassical competitive market theory explains the equilibrating forces in "double-auction"…
Neoclassical offset toroidal velocity and auxiliary ion heating in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Lazzaro, E., E-mail: lazzaro@ifp.cnr.it [Istituto di Fisica del Plasma CNR (Italy)
2016-05-15
In conditions of ideal axisymmetry, for a magnetized plasma in a generic bounded domain, necessarily toroidal, the uniform absorption of external energy (e.g., RF or any isotropic auxiliary heating) cannot give rise to net forces or torques. Experimental evidence on contemporary tokamaks shows that the near central absorption of RF heating power (ICH and ECH) and current drive in presence of MHD activity drives a bulk plasma rotation in the co-I{sub p} direction, opposite to the initial one. Also the appearance of classical or neoclassical tearing modes provides a nonlinear magnetic braking that tends to clamp the rotation profile at the q-rational surfaces. The physical origin of the torque associated with P{sub RF} absorption could be due the effects of asymmetry in the equilibrium configuration or in power deposition, but here we point out also an effect of the response of the so-called neoclassical offset velocity to the power dependent heat flow increment. The neoclassical toroidal viscosity due to internal magnetic kink or tearing modes tends to relax the plasma rotation to this asymptotic speed, which in absence of auxiliary heating is of the order of the ion diamagnetic velocity. It can be shown by kinetic and fluid calculations, that the absorption of auxiliary power by ions modifies this offset proportionally to the injected power thereby forcing the plasma rotation in a direction opposite to the initial, to large values. The problem is discussed in the frame of the theoretical models of neoclassical toroidal viscosity.
Critique of the neoclassical theory of growth and distribution
Directory of Open Access Journals (Sweden)
Luigi L. Pasinetti
2000-12-01
Full Text Available The paper surveys the main theories of income distribution in their relationship with the theories of economic growth. First, the Classical approach is considered, focusing on the Ricardian theory. Then the neoclassical theory is discussed, highlighting its origins (Bohm-Bawerk, Wicksell, Clark and the role of the aggregate production function. The emergence of a "Keynesian" theory of income distributionin the wake of Harrod's model of growth is then recalled together with the surprising resurgence of the neoclassical theory (following the contributions of Solow and Meade. But, as the paper shows, the neoclassical theory of income distributionlacks logical consistency and has shaky foundations, as has been revealed by the severecritiques moved to the neoclassical production function. Mainstream economic literature circumvents this problem by simply ignoring it, while the models of endogenous growth exclude the issue of distribution theory from their consideration. However, while mainstream economics bypasses the problems of incomedistribution, this is too relevant an issue to be ignored and a number of new research lines, briefly surveyed, try new approaches to it.
Neoclassical current effects in neutral-beam-heated tokamak discharges
International Nuclear Information System (INIS)
Hogan, J.T.
1981-01-01
There is a long-standing prediction from neoclassical theory that strong contributions to the toroidal current should be driven by friction between trapped and passing particles when βsub(pol) exceeds root (R/a) in a tokamak. A number of neutral-beam heating experiments can now produce such parameters, and it is of interest to calculate the behaviour which should occur in this regime to determine the feasibility of using such a 'bootstrap' current as a steady-state tokamak current source. It is found that the neoclassical current should be large enough to reverse the external loop voltage for typical experimental parameters (ISX-B, in particular) in cases where the total current is fixed and to produce a detectable excess of total current above the pre-programmed (demand) value in cases where the loop voltage is regulated. Other manifestations of such a current should be either: a sharp rise in the central q-value (producing a cessation of internal m=1 and m=2 MHD activity), with an enhancement by two orders of magnitude of ion thermal conductivity (due to the formation of a hollow current density profile and a consequent drop in local values of the poloidal magnetic field in the central plasma region), or an enhanced tendency for disruption (arising from magnetic reconnection in hollow-profile equilibria). Since these gross manifestations are absent in a wide range of experiments on the Impurity Study Experiment (ISX-B), as reported earlier, the conclusion is that the neoclassical current, if present, can have a value no larger than 25% of its theoretically calculated value. Since the neoclassical particle (Ware) pinch is strongly related to the neoclassical current in the theory (Onsager reciprocity), the existence of the particle pinch is thus called into question. (author)
Neoclassical effects on RF current drive in tokamaks
International Nuclear Information System (INIS)
Yoshioka, K.; Antonsen, T.M. Jr.
1986-01-01
Neoclassical effects on RF current drive which arise because of the inhomogeneity of the magnetic field in tokamak devices are analysed. A bounce averaged 2-D Fokker-Planck equation is derived from the drift kinetic equation and is solved numerically. The model features current drive due to a strong RF wave field. The efficiency of current drive by electron cyclotron waves is significantly reduced when the waves are absorbed at the low magnetic field side of a given flux surface, whereas the efficiency remains at the same level as in the homogeneous ideal plasma when the waves are absorbed at the high field side. The efficiency of current drive by fast waves (compressional Alfven waves) with low phase velocity (vsub(parallel)/vsub(th)<1) is significantly degraded by neoclassical effects, no matter where the wave is absorbed, and the applicability of this wave seems, therefore, to be doubtful. (author)
Measurement of neoclassically predicted edge current density at ASDEX Upgrade
Dunne, M. G.; McCarthy, P. J.; Wolfrum, E.; Fischer, R.; Giannone, L.; Burckhart, A.; the ASDEX Upgrade Team
2012-12-01
Experimental confirmation of neoclassically predicted edge current density in an ELMy H-mode plasma is presented. Current density analysis using the CLISTE equilibrium code is outlined and the rationale for accuracy of the reconstructions is explained. Sample profiles and time traces from analysis of data at ASDEX Upgrade are presented. A high time resolution is possible due to the use of an ELM-synchronization technique. Additionally, the flux-surface-averaged current density is calculated using a neoclassical approach. Results from these two separate methods are then compared and are found to validate the theoretical formula. Finally, several discharges are compared as part of a fuelling study, showing that the size and width of the edge current density peak at the low-field side can be explained by the electron density and temperature drives and their respective collisionality modifications.
Measurement of neoclassically predicted edge current density at ASDEX Upgrade
International Nuclear Information System (INIS)
Dunne, M.G.; McCarthy, P.J.; Wolfrum, E.; Fischer, R.; Giannone, L.; Burckhart, A.
2012-01-01
Experimental confirmation of neoclassically predicted edge current density in an ELMy H-mode plasma is presented. Current density analysis using the CLISTE equilibrium code is outlined and the rationale for accuracy of the reconstructions is explained. Sample profiles and time traces from analysis of data at ASDEX Upgrade are presented. A high time resolution is possible due to the use of an ELM-synchronization technique. Additionally, the flux-surface-averaged current density is calculated using a neoclassical approach. Results from these two separate methods are then compared and are found to validate the theoretical formula. Finally, several discharges are compared as part of a fuelling study, showing that the size and width of the edge current density peak at the low-field side can be explained by the electron density and temperature drives and their respective collisionality modifications. (paper)
δf simulation of ion neoclassical transport
International Nuclear Information System (INIS)
Wang, W.; Nakajima, N.; Okamoto, M.; Murakami, S.
1999-07-01
Ion neoclassical transport with finite orbit width dynamics is calculated over whole poloidal cross section by using accurate δf method which employs an improved like-particle collision operator and an accurate weighting scheme to solve drift kinetic equation. Ion thermal transport near magnetic axis shows a great reduction from its conventional neoclassical level due to non-standard orbit topology, like that of previous δf simulation. On other hand, the direct particle loss from confinement region may strongly increase ion energy transport near the edge. It is found that ion parallel flow near the axis is also largely reduced due to non-standard orbit topology. In the presence of steep density gradient, ion thermal conductivity is significantly reduced, and an ion particle flux is driven by self-collision alone. (author)
A neoclassical analysis of the 2001 crisis in Turkey
Türe, Elif Hatice; Ture, Elif Hatice
2008-01-01
In early 2001, Turkey experienced a severe economic crisis and many researchers attempted to qualitatively explain this downturn through analyzing the facts that caused the crisis and the effects it had on the economy. The focus of this paper is to complement these studies by quantitatively analyzing the economic fluctuations during the 2001 crisis in the light of the neoclassical growth theory. In this paper, it is shown that a standard dynamic stochastic small open economy model with exogen...
Observation of neoclassical transport in reverse shear plasmas on TFTR
International Nuclear Information System (INIS)
Efthimion, P.C.; Goeler, S. von; Houlberg, W.A.
1999-01-01
Perturbative experiments on TFTR have investigated the transport of multiple ion species in reverse shear (RS) plasmas. The profile evolutions of trace tritium and helium and intrinsic carbon indicate the formation of core particle transport barriers in enhanced reverse shear (ERS) plasmas. There is an order of magnitude reduction in the particle diffusivity inside the RS region. The diffusivities for these species in ERS plasmas agree with neoclassical theory. (author)
A novel turbulence trigger for neoclassical tearing modes in tokamaks
International Nuclear Information System (INIS)
Itoh, Sanae-I.; Yagi, Masatoshi; Itoh, Kimitaka
2003-07-01
Stochastic trigger by microturbulence for neoclassical tearing mode (NTM) is studied. NTM induces topological change of magnetic structure and has subcritical nature. Transition rate of probability density function for and statistically-averaged amplitude of NTM are obtained. Boundary in the phase diagram is determined as the statistical long time average of the transition conditions. NTM can be excited by crossing this boundary even in the absence of other global instabilities. (author)
Analysis of neoclassical edge plasma transport with gyroviscosity and inertia
International Nuclear Information System (INIS)
Rogister, A.; Antonov, N.
1996-01-01
It is shown that the ambipolarity constraint which results from neoclassical transport theory with gyroviscosity and inertia sets lower limits on the edge density and/or temperature and/or Z eff gradients. Toroidal momentum co, respectively counter, -injection reduces, respectively increases these lower bounds. Generally speaking, co, respectively counter, -injection increases, respectively reduces, the rotation velocities. The theory has so far been developed for the high collisionality regime only. (orig.)
Neoclassical transport associated with collisionless detrapping in a bumpy torus
International Nuclear Information System (INIS)
Hastings, D.E.
1983-10-01
In the two collisionality nonresonant regime in a bumpy torus the transitional particles can make a large contribution to neoclassical transport. This contribution can be moderated by the toroidally induced radial drift which causes transitional particles to detrap and retrap in the mirror sectors. This effect leads to diffusion coefficients which are linear in the collision frequency and scale with the inverse aspect ratio instead of the more usual square of the inverse aspect ratio. (author)
Nonlocal neoclassical transport in tokamak and spherical torus experiments
International Nuclear Information System (INIS)
Wang, W. X.; Rewoldt, G.; Tang, W. M.; Hinton, F. L.; Manickam, J.; Zakharov, L. E.; White, R. B.; Kaye, S.
2006-01-01
Large ion orbits can produce nonlocal neoclassical effects on ion heat transport, the ambipolar radial electric field, and the bootstrap current in realistic toroidal plasmas. Using a global δf particle simulation, it is found that the conventional local, linear gradient-flux relation is broken for the ion thermal transport near the magnetic axis. With regard to the transport level, it is found that details of the ion temperature profile determine whether the transport is higher or lower when compared with the predictions of standard neoclassical theory. Particularly, this nonlocal feature is suggested to exist in the National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)], being consistent with NSTX experimental evidence. It is also shown that a large ion temperature gradient can increase the bootstrap current. When the plasma rotation is taken into account, the toroidal rotation gradient can drive an additional parallel flow for the ions and then additional bootstrap current, either positive or negative, depending on the gradient direction. Compared with the carbon radial force balance estimate for the neoclassical poloidal flow, our nonlocal simulation predicts a significantly deeper radial electric field well at the location of an internal transport barrier of an NSTX discharge
Kinetic neoclassical transport in the H-mode pedestal
Energy Technology Data Exchange (ETDEWEB)
Battaglia, D. J.; Chang, C. S.; Ku, S.; Grierson, B. A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08540 (United States); Burrell, K. H.; Grassie, J. S. de [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
2014-07-15
Multi-species kinetic neoclassical transport through the QH-mode pedestal and scrape-off layer on DIII-D is calculated using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. Quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density, and orthogonal measurements of impurity temperature and flow profiles is achieved by adding random-walk particle diffusion to the guiding-center drift motion. The radial electric field (E{sub r}) that maintains ambipolar transport across flux surfaces and to the wall is computed self-consistently on closed and open magnetic field lines and is in excellent agreement with experiment. The E{sub r} inside the separatrix is the unique solution that balances the outward flux of thermal tail deuterium ions against the outward neoclassical electron flux and inward pinch of impurity and colder deuterium ions. Particle transport in the pedestal is primarily due to anomalous transport, while the ion heat and momentum transport are primarily due to the neoclassical transport. The full-f treatment quantifies the non-Maxwellian energy distributions that describe a number of experimental observations in low-collisionallity pedestals on DIII-D, including intrinsic co-I{sub p} parallel flows in the pedestal, ion temperature anisotropy, and large impurity temperatures in the scrape-off layer.
THE LARGE ASPECT RATIO LIMIT OF NEOCLASSICAL TRANSPORT THEORY
Energy Technology Data Exchange (ETDEWEB)
WONG,SK; CHAN,VS
2002-11-01
OAK B202 THE LARGE ASPECT RATIO LIMIT OF NEOCLASSICAL TRANSPORT THEORY. This article presents a comprehensive description of neoclassical transport theory in the banana regime for large aspect ratio flux surfaces of arbitrary shapes. The method of matched asymptotic expansions is used to obtain analytical solutions for plasma distribution functions and to compute transport coefficients. The method provides justification for retaining only the part of the Fokker-Planck operator that involves the second derivative with respect to the cosine of the pitch angle for the trapped and barely circulating particles. It leads to a simple equation for the freely circulating particles with boundary conditions that embody a discontinuity separating particles moving in opposite directions. Corrections to the transport coefficients are obtained by generalizing an existing boundary layer analysis. The system of moment and field equations is consistently taken in the cylinder limit, which facilitates discussion of the treatment of dynamical constraints. it is shown that the nonlocal nature of Ohm's law in neoclassical theory renders the mathematical problem of plasma transport with changing flux surfaces nonstandard.
THE LARGE ASPECT RATIO LIMIT OF NEOCLASSICAL TRANSPORT THEORY
International Nuclear Information System (INIS)
WONG, S.K.; CHAN, V.S.
2002-01-01
OAK B202 THE LARGE ASPECT RATIO LIMIT OF NEOCLASSICAL TRANSPORT THEORY. This article presents a comprehensive description of neoclassical transport theory in the banana regime for large aspect ratio flux surfaces of arbitrary shapes. The method of matched asymptotic expansions is used to obtain analytical solutions for plasma distribution functions and to compute transport coefficients. The method provides justification for retaining only the part of the Fokker-Planck operator that involves the second derivative with respect to the cosine of the pitch angle for the trapped and barely circulating particles. It leads to a simple equation for the freely circulating particles with boundary conditions that embody a discontinuity separating particles moving in opposite directions. Corrections to the transport coefficients are obtained by generalizing an existing boundary layer analysis. The system of moment and field equations is consistently taken in the cylinder limit, which facilitates discussion of the treatment of dynamical constraints. it is shown that the nonlocal nature of Ohm's law in neoclassical theory renders the mathematical problem of plasma transport with changing flux surfaces nonstandard
Theory of neoclassical ion temperature-gradient-driven turbulence
Kim, Y. B.; Diamond, P. H.; Biglari, H.; Callen, J. D.
1991-02-01
The theory of collisionless fluid ion temperature-gradient-driven turbulence is extended to the collisional banana-plateau regime. Neoclassical ion fluid evolution equations are developed and utilized to investigate linear and nonlinear dynamics of negative compressibility ηi modes (ηi≡d ln Ti/d ln ni). In the low-frequency limit (ωB2p. As a result of these modifications, growth rates are dissipative, rather than sonic, and radial mode widths are broadened [i.e., γ˜k2∥c2s(ηi -(2)/(3) )/μi, Δx˜ρs(Bt/Bp) (1+ηi)1/2, where k∥, cs, and ρs are the parallel wave number, sound velocity, and ion gyroradius, respectively]. In the limit of weak viscous damping, enhanced neoclassical polarization persists and broadens radial mode widths. Linear mixing length estimates and renormalized turbulence theory are used to determine the ion thermal diffusivity in both cases. In both cases, a strong favorable dependence of ion thermal diffusivity on Bp (and hence plasma current) is exhibited. Furthermore, the ion thermal diffusivity for long wavelength modes exhibits favorable density scaling. The possible role of neoclassical ion temperature-gradient-driven modes in edge fluctuations and transport in L-phase discharges and the L to H transition is discussed.
International Nuclear Information System (INIS)
Rogister, A.
1998-01-01
We show that the large negative radial electric fields which are measured in front of the separatrix in H-mode discharges are easily explainable on the basis of the rigorous 'revisited' neoclassical theory, including finite Larmor radii and inertia effects that was published earlier (Rogister A 1994 Phys. Plasmas 1 619); the same theory naturally leads to sub-neoclassical energy transport and novel particle pinch terms. The calculation has so far been developed only in the high collisionality regime: step sizes comparable to gradient-scale sizes are therefore not required to explain observed properties! Based on the analysis, we conclude that the radial electric field profile develops a well in front of the separatrix when the plasma is unable to sustain ambipolar flows otherwise. (author)
Neoclassical effects on the stabilization of tearing mode by current modulation
Energy Technology Data Exchange (ETDEWEB)
Yang, Xiaoqing, E-mail: inkyang@mail.ustc.edu.cn; Wang, Shaojie; Yang, Weihong [Department of Modern Physics, University of Science and Technology of China, Hefei, 230026 (China)
2014-02-15
The neoclassical effects on the stabilization of tearing modes by current modulation have been investigated. Neoclassical effects enhance the resistivity and reduce the resistive diffusion time of the modulation current. Therefore, the oscillating current can penetrate deeper into the plasma. With an oscillating loop voltage, the plasma oscillates radially at the Ware-pinch velocity. These neoclassical effects improve the efficiency of tearing mode stabilization by the current modulation.
A new δf method for neoclassical transport studies
International Nuclear Information System (INIS)
Wang, W.X.; Nakajima, N.; Okamoto, M.; Murakami, S.
1999-01-01
A new δf method is presented in detail to solve the drift kinetic equation for the simulation study of neoclassical transport. It is demonstrated that valid results essentially rely on the correct evaluation of the marker density g in the weight calculation. A new weighting scheme is developed without assuming g in the weight equation for advancing particle weights, unlike previous schemes. This scheme employs an additional weight function to directly solve g from its kinetic equation based on the δf method itself. Therefore, the severe constraint that the real marker distribution must be consistent with the initially assumed g is relaxed. An improved like-particle collision scheme is also presented. By compensating for momentum, energy and particle losses, the conservations of all three quantities are greatly improved during collisions. With the improvement in both the like-particle collision scheme and the weighting scheme, the δf simulation shows a significantly improved performance. The new δf method is applied to the study of ion neoclassical transports due to self-collisions, taking the effect of finite orbit width into account. The ion thermal transport near the magnetic axis is shown to be greatly reduced from its conventional neoclassical level, like that of previous δf simulations. On the other hand, the direct particle loss from the confinement region may strongly increase the ion thermal transport near the edge. It is found that the ion parallel flow near the axis is also largely reduced due to non-standard orbit topology. (author)
Effects of radial electrical field on neoclassical transport in tokamaks
International Nuclear Information System (INIS)
Wang Zhongtian; Le Clair, G.
1996-07-01
Neoclassical transport theory for tokamaks in presence of a radial electrical field with shear is developed using Hamiltonian formalism. Diffusion coefficients are derived in both plateau regime including a large electric field and banana regime including the squeezing factor which can greatly affect diffusion at the plasma edge. The scaling on squeezing factor is different from the one given by Shaing and Hazeltine. Rotation speeds are calculated in the scrape-off region. They are in good agreement with measurements on TdeV Tokamak. (2 figs.)
Neoclassical toroidal viscosity in perturbed equilibria with general tokamak geometry
Energy Technology Data Exchange (ETDEWEB)
Logan, Nikolas C.; Park, Jong-Kyu; Kim, Kimin; Wang, Zhirui [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Berkery, John W. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
2013-12-15
This paper presents a calculation of neoclassical toroidal viscous torque independent of large-aspect-ratio expansions across kinetic regimes. The Perturbed Equilibrium Nonambipolar Transport (PENT) code was developed for this purpose, and is compared to previous combined regime models as well as regime specific limits and a drift kinetic δf guiding center code. It is shown that retaining general expressions, without circular large-aspect-ratio or other orbit approximations, can be important at experimentally relevant aspect ratio and shaping. The superbanana plateau, a kinetic resonance effect recently recognized for its relevance to ITER, is recovered by the PENT calculations and shown to require highly accurate treatment of geometric effects.
Neoclassical tearing mode stabilization by ECCD in ITER
International Nuclear Information System (INIS)
Giruzzi, G.; Zabiego, M.
2001-01-01
A dynamic model, based on a 3-D Fokker-Planck code coupled to the island evolution equations, is used to evaluate the feasibility of active control of Neoclassical Tearing modes by Electron Cyclotron Current Drive (ECCD) in International Thermonuclear Experimental Reactor (ITER). The parameters of the present version of ITER, i.e., RTO/RC ITER (IAM option) are used. Both m=3, n=2 and m=2, n=1 modes are considered. It is shown that an Electron Cyclotron wave system at 140 GHz, with toroidally steerable antennas, can stabilize both modes simultaneously if a power ≥30 MW is available
The Artistic Commitment of Kenyon Cox: An American Neoclassical Artist
SMITH, Marc S.
2016-01-01
At the end of the nineteenth century, the United States had undergone deep transformations. The second Industrial Revolution had created huge amounts of new wealth and power. This led to an alteration of the urban social fabric and to a repositioning of the country on the international scene.Since the 1870s, the American Renaissance had been a vehicle for the diffusion of new values and new concepts. As a broad neoclassical movement in the arts, it was committed to a rewriting of the country’...
Observations of neoclassical and anomalous resistivity in toroidal discharges
International Nuclear Information System (INIS)
Etzweiler, J.F.; Brouchous, D.A.
1980-03-01
Plasma resistivity measurements parallel to the magnetic field have been made on the .Wisconsin supported octupole and the Wisconsin levitated octupole. Plasmas ranged in density from 10 8 cm -3 to 10 12 cm -3 and varied from highly collisionless to highly collisional. The measured resistivity was found to agree with neoclassical resistivity theory in the collisional and transition regimes. Highly collisionless plasmas were found to have anomalously high resistivity which obeyed the T/sub e//sup 1/2//n/sub e/ scaling of the transition regime
A minimal collision operator for implementing neoclassical transport in gyrokinetic simulations
International Nuclear Information System (INIS)
Garbet, X.; Dif-Pradalier, G.; Nguyen, C.; Angelino, P.; Sarazin, Y.; Grandgirard, V.; Ghendrih, P.; Samain, A.
2008-01-01
This paper presents a class of collision operators, which reproduce neoclassical transport and comply with the constraints of a full-f global gyrokinetic code. The assessment of these operators is based on a variational entropy method, which allows a fast calculation of the neoclassical diffusivity and poloidal velocity.
Clark, Charles Michael Andres
2014-01-01
The financial crisis was partially caused by neoclassical economic theory and theorists. This failure has prompted business educators to rethink the role of neoclassical economics as the foundation of business education. The author connects this question to the more general critique of the scientific model of business education and the old…
Neoclassical impurity transport in the presence of toroidal and poloidal rotation
International Nuclear Information System (INIS)
Feneberg, W.
1988-06-01
This paper presents an extended theory of neoclassical impurity transport, starting from the parameters of bulk plasma toroidal and poloidal rotation. Analytic expressions resulting from the influence of a compressible flow on the perpendicular momentum balance and on the neoclassical Braginskii parallel viscosity are derived. The predicted impurity transport is extensively compared with that in earlier papers. (orig.)
Test of the neoclassical theory of radiation in a weakly excited atomic system
International Nuclear Information System (INIS)
Brink, G.O.
1975-01-01
The neoclassical theory of radiation predicts that the decay rate of an excited atomic state depends on the population density of the lower state. Experimental evidence is presented here which shows that in the case of 39 K the decay rate is in agreement with the predictions of quantum electrodynamics and definitely in disagreement with the neoclassical theory
Computational modeling of neoclassical and resistive MHD tearing modes in tokamaks
International Nuclear Information System (INIS)
Gianakon, T.A.; Hegna, C.C.; Callen, J.D.
1996-01-01
Numerical studies of the nonlinear evolution of MHD-type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion of neoclassical physics introduces an additional free-energy source for the nonlinear formation of magnetic islands through the effects of a bootstrap current in Ohm's law. The neoclassical tearing mode is demonstrated to be destabilized in plasmas which are otherwise Δ' stable, albeit once an island width threshold is exceeded. The plasma pressure dynamics and neoclassical tearing growth is shown to be sensitive to the choice of the ratio of the parallel to perpendicular diffusivity (Χ parallel/Χ perpendicular). The study is completed with a demonstration and theoretical comparison of the threshold for single helicity neoclassical MHD tearing modes, which is described based on parameter scans of the local pressure gradient, the ratio of perpendicular to parallel pressure diffusivities Χ perpendicular/Χ parallel, and the magnitude of an initial seed magnetic perturbation
International Nuclear Information System (INIS)
Spong, D.A.; Shaing, K.C.; Carreras, B.A.; Charlton, L.A.; Callen, J.D.; Garcia, L.
1988-10-01
The linearized neoclassical magnetohydrodynamic equations, including perturbed neoclassical flows and currents, have been solved for parameter regimes where the neoclassical pressure-gradient-driven instability becomes important. This instability is driven by the fluctuating bootstrap current term in Ohm's law. It begins to dominate the conventional resistive ballooning mode in the banana-plateau collisionality regime [μ/sub e//ν/sub e/ /approximately/ √ε/(1 + ν/sub *e/) > ε 2 ] and is characterized by a larger radial mode width and higher growth rate. The neoclassical instability persists in the absence of the usual magnetic field curvature drive and is not significantly affected by compressibility. Scalings with respect to β, n (toroidal mode number), and μ (neoclassical viscosity) are examined using a large-aspect-ratio, three-dimensional initial-value code that solves linearized equations for the magnetic flux, fluid vorticity, density, and parallel ion flow velocity in axisymmetric toroidal geometry. 13 refs., 10 figs
Theory of neoclassical resistivity-gradient-driven turbulence
International Nuclear Information System (INIS)
Kwon, O.J.; Diamond, P.H.; Hahm, T.S.
1988-12-01
It is shown that rippling instabilities can tap the density gradient expansion free energy source through the density dependence of the neoclassical resistivity. Linear analyses show that the region where neoclassical rippling modes are significantly excited extends from the edge of the plasma to the region where ν/sub *e/ ≤ 1. Since these modes are non-dispersive, diamagnetic effects are negligible in comparison to the nonlinear decorrelation rate at saturation. Thus, the relevant regime is the 'strong turbulence' regime. The turbulent radial diffusivities of the temperature and the density are obtained as eigenvalues of the renormalized eigenmode equations at steady state. The density gradient acts to enhance the level of turbulence, compared to that driven by the temperature gradient alone. The saturated turbulent state is characterized by: current decoupling, the breakdown of Boltzmann relation, a radial mode scale of density fluctuations exceeding that of temperature fluctuations, implying that density diffusivity exceeds temperature diffusivity, and that density fluctuation levels exceed temperature fluctuation levels. Magnetic fluctuation levels are negligible. 29 refs., 1 fig
Large-aspect-ratio limit of neoclassical transport theory
International Nuclear Information System (INIS)
Wong, S K.; Chan, V.S.
2003-01-01
This paper presents a comprehensive description of neoclassical transport theory in the banana regime for large-aspect-ratio flux surfaces of arbitrary shapes. The method of matched-asymptotic expansions is used to obtain analytical solutions for plasma distribution functions and to compute transport coefficients. The method provides justification for retaining only the part of the Fokker-Planck operator that involves the second derivative with respect to the cosine of the pitch angle for the trapped and barely circulating particles. It leads to a simple equation for the freely circulating particles with boundary conditions that embody a discontinuity separating particles moving in opposite directions. Corrections to the transport coefficients are obtained by generalizing an existing boundary layer analysis. The system of moment and field equations is consistently taken in the cylinder limit, which facilitates the discussion of the treatment of dynamical constraints. It is shown that the nonlocal nature of Ohm's law in neoclassical theory renders the mathematical problem of plasma transport with changing flux surfaces nonstandard
Large-aspect-ratio limit of neoclassical transport theory.
Wong, S K; Chan, V S
2003-06-01
This paper presents a comprehensive description of neoclassical transport theory in the banana regime for large-aspect-ratio flux surfaces of arbitrary shapes. The method of matched-asymptotic expansions is used to obtain analytical solutions for plasma distribution functions and to compute transport coefficients. The method provides justification for retaining only the part of the Fokker-Planck operator that involves the second derivative with respect to the cosine of the pitch angle for the trapped and barely circulating particles. It leads to a simple equation for the freely circulating particles with boundary conditions that embody a discontinuity separating particles moving in opposite directions. Corrections to the transport coefficients are obtained by generalizing an existing boundary layer analysis. The system of moment and field equations is consistently taken in the cylinder limit, which facilitates the discussion of the treatment of dynamical constraints. It is shown that the nonlocal nature of Ohm's law in neoclassical theory renders the mathematical problem of plasma transport with changing flux surfaces nonstandard.
Sousa, Tânia; Domingos, Tiago
2006-11-01
We develop a unified conceptual and mathematical structure for equilibrium econophysics, i.e., the use of concepts and tools of equilibrium thermodynamics in neoclassical microeconomics and vice versa. Within this conceptual structure the results obtained in microeconomic theory are: (1) the definition of irreversibility in economic behavior; (2) the clarification that the Engel curve and the offer curve are not descriptions of real processes dictated by the maximization of utility at constant endowment; (3) the derivation of a relation between elasticities proving that economic elasticities are not all independent; (4) the proof that Giffen goods do not exist in a stable equilibrium; (5) the derivation that ‘economic integrability’ is equivalent to the generalized Le Chatelier principle and (6) the definition of a first order phase transition, i.e., a transition between separate points in the utility function. In thermodynamics the results obtained are: (1) a relation between the non-dimensional isothermal and adiabatic compressibilities and the increase or decrease in the thermodynamic potentials; (2) the distinction between mathematical integrability and optimization behavior and (3) the generalization of the Clapeyron equation.
Does mental exertion alter maximal muscle activation?
Directory of Open Access Journals (Sweden)
Vianney eRozand
2014-09-01
Full Text Available Mental exertion is known to impair endurance performance, but its effects on neuromuscular function remain unclear. The purpose of this study was to test the hypothesis that mental exertion reduces torque and muscle activation during intermittent maximal voluntary contractions of the knee extensors. Ten subjects performed in a randomized order three separate mental exertion conditions lasting 27 minutes each: i high mental exertion (incongruent Stroop task, ii moderate mental exertion (congruent Stroop task, iii low mental exertion (watching a movie. In each condition, mental exertion was combined with ten intermittent maximal voluntary contractions of the knee extensor muscles (one maximal voluntary contraction every 3 minutes. Neuromuscular function was assessed using electrical nerve stimulation. Maximal voluntary torque, maximal muscle activation and other neuromuscular parameters were similar across mental exertion conditions and did not change over time. These findings suggest that mental exertion does not affect neuromuscular function during intermittent maximal voluntary contractions of the knee extensors.
International Nuclear Information System (INIS)
Matsuoka, Seikichi; Satake, Shinsuke; Kanno, Ryutaro; Sugama, Hideo
2015-01-01
In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field E r . The peaked behavior of the neoclassical radial fluxes around E r = 0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account
Energy Technology Data Exchange (ETDEWEB)
Matsuoka, Seikichi, E-mail: matsuoka@rist.or.jp [Research Organization for Information Science and Technology, 6F Kimec-Center Build., 1-5-2 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047 (Japan); Satake, Shinsuke; Kanno, Ryutaro [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Department of Fusion Science, SOKENDAI (The Graduate University for Advanced Studies), 322-6 Oroshi-cho, Toki 509-5292 (Japan); Sugama, Hideo [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
2015-07-15
In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field E{sub r}. The peaked behavior of the neoclassical radial fluxes around E{sub r }={sub }0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account.
International Nuclear Information System (INIS)
Lore, J.; Briesemeister, A.; Anderson, D. T.; Anderson, F. S. B.; Likin, K. M.; Talmadge, J. N.; Zhai, K.; Guttenfelder, W.; Deng, C. B.; Spong, D. A.
2010-01-01
Electron cyclotron heated plasmas in the Helically Symmetric Experiment (HSX) feature strongly peaked electron temperature profiles; central temperatures are 2.5 keV with 100 kW injected power. These measurements, coupled with neoclassical predictions of large 'electron root' radial electric fields with strong radial shear, are evidence of a neoclassically driven thermal transport barrier. Neoclassical transport quantities are calculated using the PENTA code [D. A. Spong, Phys. Plasmas 12, 056114 (2005)], in which momentum is conserved and parallel flow is included. Unlike a conventional stellarator, which exhibits strong flow damping in all directions on a flux surface, quasisymmetric stellarators are free to rotate in the direction of symmetry, and the effect of momentum conservation in neoclassical calculations may therefore be significant. Momentum conservation is shown to modify the neoclassical ion flux and ambipolar ion root radial electric fields in the quasisymmetric configuration. The effect is much smaller in a HSX configuration where the symmetry is spoiled. In addition to neoclassical transport, a model of trapped electron mode turbulence is used to calculate the turbulent-driven electron thermal diffusivity. Turbulent transport quenching due to the neoclassically predicted radial electric field profile is needed in predictive transport simulations to reproduce the peaking of the measured electron temperature profile [Guttenfelder et al., Phys. Rev. Lett. 101, 215002 (2008)].
EFFECTS OF ELECTROMAGNETIC TURBULENCE IN THE NEOCLASSICAL OHM's LAW
International Nuclear Information System (INIS)
HINTON, F.L; WALTZ, R.E; CANDY, J.
2003-01-01
OAK-B135 An Ohm's law for tokamak plasmas has been derived, which includes the effect of electromagnetic turbulence as well as the neoclassical conductivity and bootstrap current. The most important current-driving effects of the turbulence have been identified, expressions for the driven (dynamo) current have been derived and these have been evaluated using the GYRO electromagnetic turbulence code. The most important current drive mechanism, the divergence of the radial flux of parallel electron momentum induced by magnetic flutter, drives a current density which have positive peaks on low order rational surfaces, with compensating negative dips nearby, thus driving zero total current. Another current drive mechanism, the beating of the parallel electric field fluctuations with the electron density fluctuations, drives a current density which is much smaller than that driven by the magnetic flutter mechanism, but could drive a nonzero total current
Neoclassical impurity transport and observations of poloidal asymmetries in JET
International Nuclear Information System (INIS)
Feneberg, W.; Mast, F.K.; Martin, P.; Gottardi, N.
1986-01-01
Bolometrically measured asymmetries of emissivity for some characteristic JET discharges are presented and are in good agreement with theoretical results of calculations worked out in the frame of neoclassical theory. Application of theory to the case of strong toroidal rotation as induced with neutral injection shows a sensitive dependance of the impurity transport perpendicular to the magnetic surfaces from the parameter of poloidal rotation. The main result is the existence of a classical flow reversal. Without any poloidal rotation of the background ions, a large inward flow of impurities for co- and counter-injection is always predicted, while poloidal rotation in the direction of the ion diamagnetic drift motion leads to a strong outward drift. (author)
Influence of collision frequency on neoclassical polarization current
International Nuclear Information System (INIS)
Imada, K; Wilson, H R
2009-01-01
A kinetic theory for the evolution of magnetic islands is considered in a tokamak plasma, in both the low (ν i i >> εω) collision frequency limits (ν i is the ion collision frequency, ε is the inverse aspect ratio and ω is the island propagation frequency in the E x B rest frame). The calculation of the bootstrap current perturbation in the presence of a magnetic island is reviewed, and is confirmed to be independent of ω and the collision frequency regime. The neoclassical polarization current perturbation is calculated in the two collision frequency limits (within the banana regime). The result in the collisional limit is in agreement with a fluid theory. The effect of collisions in the 'dissipation layer' at the trapped/passing boundary is also considered, for ν i i /εω] 1/2 , where r is a weak logarithmic function of √ν i /εω.
Maximally incompatible quantum observables
Energy Technology Data Exchange (ETDEWEB)
Heinosaari, Teiko, E-mail: teiko.heinosaari@utu.fi [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Schultz, Jussi, E-mail: jussi.schultz@gmail.com [Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Toigo, Alessandro, E-mail: alessandro.toigo@polimi.it [Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ziman, Mario, E-mail: ziman@savba.sk [RCQI, Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava (Slovakia); Faculty of Informatics, Masaryk University, Botanická 68a, 60200 Brno (Czech Republic)
2014-05-01
The existence of maximally incompatible quantum observables in the sense of a minimal joint measurability region is investigated. Employing the universal quantum cloning device it is argued that only infinite dimensional quantum systems can accommodate maximal incompatibility. It is then shown that two of the most common pairs of complementary observables (position and momentum; number and phase) are maximally incompatible.
Maximally incompatible quantum observables
International Nuclear Information System (INIS)
Heinosaari, Teiko; Schultz, Jussi; Toigo, Alessandro; Ziman, Mario
2014-01-01
The existence of maximally incompatible quantum observables in the sense of a minimal joint measurability region is investigated. Employing the universal quantum cloning device it is argued that only infinite dimensional quantum systems can accommodate maximal incompatibility. It is then shown that two of the most common pairs of complementary observables (position and momentum; number and phase) are maximally incompatible.
Interaction between the neoclassical equilibrium and microturbulence in gyrokinetic simulations
Energy Technology Data Exchange (ETDEWEB)
Oberparleiter, Michael
2015-07-10
For the application of the nuclear fusion of hydrogen as a heat source for electricity generation understanding of the magnetic fuel confinement is crucial. Most of the cross-field transport in modern-day tokamaks is carried by turbulence driven by steep pressure gradients. Background neoclassical transport, however, provides a steady level of cross-field flux even in cases when turbulence becomes weak or suppressed. The goal of this work is to quantify how neoclassical (NC) effects and turbulence can influence each other. For this purpose the nonlinear gyrokinetic turbulence code GENE is employed. Firstly, its ability to self-consistently calculate the NC radial electric field is successfully benchmarked against the radial force balance equation and NC transport in the plasma region close to the center of a tokamak is studied. In the next step a model system where a long-wavelength external potential is imposed on ion temperature gradient-driven (ITG) turbulence is investigated. It is found that the self-generated shear flow pattern of the turbulence adapts to the imposed pattern and a small external shear is sufficient to notably reduce turbulent transport. Motivated by this global ITG simulations with fixed pressure gradient profiles are performed with and without inclusion of NC effects. Their comparison reveals that the NC field enhances turbulent transport by 20-30 % for a ratio of ion gyroradius and device radius larger than 1/300. An explanation is that the NC field aligns a region of low shear with the maximum of the gradient profile where the turbulent drive is strongest. Further investigation reveals that NC effects also change the dependence of the system on collisionality or safety factor. Finally, in physically more comprehensive simulations with fixed power input and a self-consistently evolving temperature profile, the additional NC transport channel is found to reduce the frequency and amplitude of intermittent turbulent transport bursts.
Improved method for calculating neoclassical transport coefficients in the banana regime
Energy Technology Data Exchange (ETDEWEB)
Taguchi, M., E-mail: taguchi.masayoshi@nihon-u.ac.jp [College of Industrial Technology, Nihon University, Narashino 275-8576 (Japan)
2014-05-15
The conventional neoclassical moment method in the banana regime is improved by increasing the accuracy of approximation to the linearized Fokker-Planck collision operator. This improved method is formulated for a multiple ion plasma in general tokamak equilibria. The explicit computation in a model magnetic field shows that the neoclassical transport coefficients can be accurately calculated in the full range of aspect ratio by the improved method. The some neoclassical transport coefficients for the intermediate aspect ratio are found to appreciably deviate from those obtained by the conventional moment method. The differences between the transport coefficients with these two methods are up to about 20%.
International Nuclear Information System (INIS)
Taguchi, Masayoshi
1999-01-01
The neoclassical transport theory in a presence of temperature anisotropy is investigated in the low to the intermediate collision frequency regimes for a large aspect-ratio tokamak plasma. The standard procedure for an isotropic plasma in the plateau regime is extended to an anisotropic plasma, and the neoclassical transport coefficients in this regime are explicitly calculated. By interpolating the results in the plateau regime and the previously obtained ones in the banana regime, the expressions for the neoclassical transport coefficients which are continuously valid from the banana to the plateau regimes are presented. (author)
Radially global δf computation of neoclassical phenomena in a tokamak pedestal
International Nuclear Information System (INIS)
Landreman, Matt; Parra, Felix I; Catto, Peter J; Ernst, Darin R; Pusztai, Istvan
2014-01-01
Conventional radially-local neoclassical calculations become inadequate if the radial gradient scale lengths of the H-mode pedestal become as small as the poloidal ion gyroradius. Here, we describe a radially global δf continuum code that generalizes neoclassical calculations to allow for stronger gradients. As with conventional neoclassical calculations, the formulation is time-independent and requires only the solution of a single sparse linear system. We demonstrate precise agreement with an asymptotic analytic solution of the radially global kinetic equation in the appropriate limits of aspect ratio and collisionality. This agreement depends crucially on accurate treatment of finite orbit width effects. (paper)
Neoclassical transport of energetic beam ions in the Large Helical Device
International Nuclear Information System (INIS)
Murakami, Sadayoshi; Yamada, Hiroshi; Kaneko, Osamu
2000-01-01
The neoclassical (collisional) transport of energetic ions is investigated by the global neoclassical transport simulation in the Large Helical Device (LHD). The steady state distributions of energetic ions are evaluated assuming an energetic particle source by NBI heating (tangentally injected). Significant radial transport of energetic ions can be seen due to the radial motion of trapped particles in the velocity region below near critical velocity. Our simulation results show relatively good agreements with the experimental results of fast particle measurements in the LHD. This suggests an important role of neoclassical transport in the radial transport process of energetic ions in heliotrons. (author)
Neoclassical transport, poloidal rotation and radial electric field at the L-H transition
International Nuclear Information System (INIS)
Minardi, E.; Gervasini, G.; Lazzaro, E.
1993-01-01
The transition to a high confinement regime in tokamaks operating with a magnetic divertor configuration is accompanied by the strong steepening of the edge temperature profile and the onset of a large positive poloidal mass rotation associated with a negative radial electric field. The latter phenomena are signatures of a neoclassical transport mechanism. We address the question of establishing whether neoclassical transport is indeed sufficient to establish high edge gradients and drive poloidal rotation under strong auxiliary heating. The heat transport equation is solved numerically in a narrow edge layer interfaced to the plasma body through heat flux continuity, but allowing for heat conductivity discontinuity. The results compared with recent experimental measurements support the assumption that a highly sheared neoclassical poloidal velocity profile can suppress the anomalous part of the heat transport, and that the neoclassical residual transport, characterizes the plasma behaviour at the edge during H modes. (author) 3 refs., 4 figs
Neoclassical viscous stress tensor for non-linear MHD simulations with XTOR-2F
International Nuclear Information System (INIS)
Mellet, N.; Maget, P.; Meshcheriakov, D.; Lütjens, H.
2013-01-01
The neoclassical viscous stress tensor is implemented in the non-linear MHD code XTOR-2F (Lütjens and Luciani 2010 J. Comput. Phys. 229 8130–43), allowing consistent bi-fluid simulations of MHD modes, including the metastable branch of neoclassical tearing modes (NTMs) (Carrera et al 1986 Phys. Fluids 29 899–902). Equilibrium flows and bootstrap current from the neoclassical theory are formally recovered in this Chew–Goldberger–Low formulation. The non-linear behaviour of the new model is verified on a test case coming from a Tore Supra non-inductive discharge. A NTM threshold that is larger than with the previous model is obtained. This is due to the fact that the velocity is now part of the bootstrap current and that it differs from the theoretical neoclassical value. (paper)
Neoclassical resonant-plateau transport in the noncircular equipotential surface of a tandem mirror
International Nuclear Information System (INIS)
Katanuma, I.; Kiwamoto, Y.; Ishii, K.; Yatsu, K.; Miyoshi, S.
1988-07-01
Neoclassical resonant-plateau transport in a minimum-B anchored tandem mirror is calculated in an experimentally observed case that a magnetic flux tube of an equipotential contours is not circular at the central cell. (author)
Neoclassical resonant-plateau transport in the noncircular equipotential surface of a tandem mirror
International Nuclear Information System (INIS)
Katanuma, I.; Kiwamoto, Y.; Ishii, K.; Yatsu, K.; Miyoshi, S.
1989-01-01
Neoclassical resonant-plateau transport in a minimum-B anchored tandem mirror is calculated in an experimentally observed case where a flux tube of equipotential contours is not circular at the central cell
Effect of magnetic axis shift on neoclassical transport in helical torus
International Nuclear Information System (INIS)
Sanuki, Heiji; Todoroki, Jiro
2004-01-01
Neoclassical transport for large helical device (LHD) configurations is studied by solving the bounce-averaged Fokker-Planck equation. Numerical code employed in the present paper (CHD1) is much faster and more efficient than existing transport codes. Effects of the magnetic axis shift on the mono-energetic transport coefficients are studied in detail for the LHD configurations, revealing that a strong inward shift of the magnetic axis can reduce remarkably the neoclassical ripple transport. (author)
Self-consistent gyrokinetic modeling of neoclassical and turbulent impurity transport
Estève , D. ,; Sarazin , Y.; Garbet , X.; Grandgirard , V.; Breton , S. ,; Donnel , P. ,; Asahi , Y. ,; Bourdelle , C.; Dif-Pradalier , G; Ehrlacher , C.; Emeriau , C.; Ghendrih , Ph; Gillot , C.; Latu , G.; Passeron , C.
2018-01-01
International audience; Trace impurity transport is studied with the flux-driven gyrokinetic GYSELA code [V. Grandgirard et al., Comp. Phys. Commun. 207, 35 (2016)]. A reduced and linearized multi-species collision operator has been recently implemented, so that both neoclassical and turbulent transport channels can be treated self-consistently on an equal footing. In the Pfirsch-Schlüter regime likely relevant for tungsten, the standard expression of the neoclassical impurity flux is shown t...
Andrew M. Parker; Wandi Bruine de Bruin; Baruch Fischhoff
2007-01-01
Our previous research suggests that people reporting a stronger desire to maximize obtain worse life outcomes (Bruine de Bruin et al., 2007). Here, we examine whether this finding may be explained by the decision-making styles of self-reported maximizers. Expanding on Schwartz et al. (2002), we find that self-reported maximizers are more likely to show problematic decision-making styles, as evidenced by self-reports of less behavioral coping, greater dependence on others when making decisions...
Maximal combustion temperature estimation
International Nuclear Information System (INIS)
Golodova, E; Shchepakina, E
2006-01-01
This work is concerned with the phenomenon of delayed loss of stability and the estimation of the maximal temperature of safe combustion. Using the qualitative theory of singular perturbations and canard techniques we determine the maximal temperature on the trajectories located in the transition region between the slow combustion regime and the explosive one. This approach is used to estimate the maximal temperature of safe combustion in multi-phase combustion models
Self-consistent gyrokinetic modeling of neoclassical and turbulent impurity transport
Estève, D.; Sarazin, Y.; Garbet, X.; Grandgirard, V.; Breton, S.; Donnel, P.; Asahi, Y.; Bourdelle, C.; Dif-Pradalier, G.; Ehrlacher, C.; Emeriau, C.; Ghendrih, Ph.; Gillot, C.; Latu, G.; Passeron, C.
2018-03-01
Trace impurity transport is studied with the flux-driven gyrokinetic GYSELA code (Grandgirard et al 2016 Comput. Phys. Commun. 207 35). A reduced and linearized multi-species collision operator has been recently implemented, so that both neoclassical and turbulent transport channels can be treated self-consistently on an equal footing. In the Pfirsch-Schlüter regime that is probably relevant for tungsten, the standard expression for the neoclassical impurity flux is shown to be recovered from gyrokinetics with the employed collision operator. Purely neoclassical simulations of deuterium plasma with trace impurities of helium, carbon and tungsten lead to impurity diffusion coefficients, inward pinch velocities due to density peaking, and thermo-diffusion terms which quantitatively agree with neoclassical predictions and NEO simulations (Belli et al 2012 Plasma Phys. Control. Fusion 54 015015). The thermal screening factor appears to be less than predicted analytically in the Pfirsch-Schlüter regime, which can be detrimental to fusion performance. Finally, self-consistent nonlinear simulations have revealed that the tungsten impurity flux is not the sum of turbulent and neoclassical fluxes computed separately, as is usually assumed. The synergy partly results from the turbulence-driven in-out poloidal asymmetry of tungsten density. This result suggests the need for self-consistent simulations of impurity transport, i.e. including both turbulence and neoclassical physics, in view of quantitative predictions for ITER.
Environmental policy without costs? A review of the Porter hypothesis
Energy Technology Data Exchange (ETDEWEB)
Braennlund, Runar; Lundgren, Tommy. e-mail: runar.brannlund@econ.umu.se
2009-03-15
This paper reviews the theoretical and empirical literature connected to the so called Porter Hypothesis. That is, to review the literature connected to the discussion about the relation between environmental policy and competitiveness. According to the conventional wisdom environmental policy, aiming for improving the environment through for example emission reductions, do imply costs since scarce resources must be diverted from somewhere else. However, this conventional wisdom has been challenged and questioned recently through what has been denoted the 'Porter hypothesis'. Those in the forefront of the Porter hypothesis challenge the conventional wisdom basically on the ground that resources are used inefficiently in the absence of the right kind of environmental regulations, and that the conventional neo-classical view is too static to take inefficiencies into account. The conclusions that can be made from this review is (1) that the theoretical literature can identify the circumstances and mechanisms that must exist for a Porter effect to occur, (2) that these circumstances are rather non-general, hence rejecting the Porter hypothesis in general, (3) that the empirical literature give no general support for the Porter hypothesis. Furthermore, a closer look at the 'Swedish case' reveals no support for the Porter hypothesis in spite of the fact that Swedish environmental policy the last 15-20 years seems to be in line the prerequisites stated by the Porter hypothesis concerning environmental policy
Maximally multipartite entangled states
Facchi, Paolo; Florio, Giuseppe; Parisi, Giorgio; Pascazio, Saverio
2008-06-01
We introduce the notion of maximally multipartite entangled states of n qubits as a generalization of the bipartite case. These pure states have a bipartite entanglement that does not depend on the bipartition and is maximal for all possible bipartitions. They are solutions of a minimization problem. Examples for small n are investigated, both analytically and numerically.
Isotope and mixture effects on neoclassical transport in the pedestal
Pusztai, Istvan; Buller, Stefan; Omotani, John T.; Newton, Sarah L.
2017-10-01
The isotope mass scaling of the energy confinement time in tokamak plasmas differs from gyro-Bohm estimates, with implications for the extrapolation from current experiments to D-T reactors. Differences in mass scaling in L-mode and various H-mode regimes suggest that the isotope effect may originate from the pedestal. In the pedestal, sharp gradients render local diffusive estimates invalid, and global effects due to orbit-width scale profile variations have to be taken into account. We calculate neoclassical cross-field fluxes from a radially global drift-kinetic equation using the PERFECT code, to study isotope composition effects in density pedestals. The relative reduction to the peak heat flux due to global effects as a function of the density scale length is found to saturate at an isotope-dependent value that is larger for heavier ions. We also consider D-T and H-D mixtures with a focus on isotope separation. The ability to reproduce the mixture results via single-species simulations with artificial ``DT'' and ``HD'' species has been considered. These computationally convenient single ion simulations give a good estimate of the total ion heat flux in corresponding mixtures. Funding received from the International Career Grant of Vetenskapsradet (VR) (330-2014-6313) with Marie Sklodowska Curie Actions, Cofund, Project INCA 600398, and Framework Grant for Strategic Energy Research of VR (2014-5392).
Increased understanding of neoclassical internal transport barrier on CHS
International Nuclear Information System (INIS)
Minami, T.; Fujisawa, A.; Iguchi, H.
2002-10-01
We report the recent progress of the study on neoclassical internal transport barrier (N-ITB) on Compact Helical System experiment. N-ITB has been observed for EC heated NBI plasma. The improved confinement region for electrons is expanded compared to that of the previous N-ITB plasma heated by only ECH. Moreover, the ion temperature is found to be increased simultaneously by about two to three times (T i (0) ∼ 400-500 eV) with steep gradient region at ρ - 0.6. From the measurement of the averaged peak energy intensity using the soft X-ray CCD camera it is confirmed that the impurity confinement is also improved with N-ITB. The radial electric field is observed to bifurcate into electron root (E r - 15 kV/m) and rather large electric field shear (dE r /dr - 300 kV/m 2 ) is produced in the layer between ion and electron root. (author)
Increased understanding of neoclassical internal transport barrier on CHS
International Nuclear Information System (INIS)
Minami, T.; Fujisawa, A.; Iguchi, H.
2003-01-01
We report the recent progress of the study on neoclassical internal transport barrier (N-ITB) on Compact Helical System experiment. N-ITB has been observed for EC heated NBI plasma. The improved confinement region for electrons is expanded compared to that of the previous N-ITB plasma heated by only ECH. Moreover, the ion temperature is found to be increased simultaneously by about two to three times (T i (0)∼400-500eV) with steep gradient region at ρ∼0.6. From the measurement of the averaged peak energy intensity using the soft X-ray CCD camera it is confirmed that the impurity confinement is also improved with N-ITB. The radial electric field is observed to bifurcate into electron root (E r ∼15kV/m) and rather large electric field shear (dE r /dr∼300kV/m 2 ) is produced in the layer between ion and electron root. (author)
Theory comparison and numerical benchmarking on neoclassical toroidal viscosity torque
Energy Technology Data Exchange (ETDEWEB)
Wang, Zhirui; Park, Jong-Kyu; Logan, Nikolas; Kim, Kimin; Menard, Jonathan E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Liu, Yueqiang [Euratom/CCFE Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
2014-04-15
Systematic comparison and numerical benchmarking have been successfully carried out among three different approaches of neoclassical toroidal viscosity (NTV) theory and the corresponding codes: IPEC-PENT is developed based on the combined NTV theory but without geometric simplifications [Park et al., Phys. Rev. Lett. 102, 065002 (2009)]; MARS-Q includes smoothly connected NTV formula [Shaing et al., Nucl. Fusion 50, 025022 (2010)] based on Shaing's analytic formulation in various collisionality regimes; MARS-K, originally computing the drift kinetic energy, is upgraded to compute the NTV torque based on the equivalence between drift kinetic energy and NTV torque [J.-K. Park, Phys. Plasma 18, 110702 (2011)]. The derivation and numerical results both indicate that the imaginary part of drift kinetic energy computed by MARS-K is equivalent to the NTV torque in IPEC-PENT. In the benchmark of precession resonance between MARS-Q and MARS-K/IPEC-PENT, the agreement and correlation between the connected NTV formula and the combined NTV theory in different collisionality regimes are shown for the first time. Additionally, both IPEC-PENT and MARS-K indicate the importance of the bounce harmonic resonance which can greatly enhance the NTV torque when E×B drift frequency reaches the bounce resonance condition.
Electromagnetic and quantum measurements a bitemporal neoclassical theory
Wessel-Berg, Tore
2001-01-01
It is a pleasure to write a foreword for Professor Tore Wessel-Berg's book, "Electromagnetic and Quantum Measurements: A Bitemporal Neoclassical Theory." This book appeals to me for several reasons. The most important is that, in this book, Wessel-Berg breaks from the pack. The distinguished astrophysicist Thomas Gold has written about the pressures on scientists to move in tight formation, to avoid having their legs nipped by the sheepdogs of science. This book demonstrates that Wessel-Berg is willing to take that risk. I confess that I do not sufficiently understand this book to be able to either agree or disagree with its thesis. Nevertheless, Wessel-Berg makes very cogent arguments for setting out on his journey. The basic equations of physics are indeed time-reversible. Our experience, that leads us to the concept of an "arrow of time," is derived from macro scopic phenomena, not from fundamental microscopic phenomena. For this reason, it makes very good sense to explore the consequences of treating mi...
Increased understanding of neoclassical internal transport barrier on CHS
International Nuclear Information System (INIS)
Minami, T.; Fujisawa, A.; Iguchi, H.
2002-01-01
We report the recent progress of the study on neoclassical internal transport barrier (N-ITB) on Compact Helical System experiment. N-ITB has been observed for EC heated NBI plasma. The improved confinement region for electrons is expanded compared to that of the previous N-ITB plasma heated by only ECH. Moreover, the ion temperature is found to be increased simultaneously by about two to three times (T i (0)∼400-500eV) with steep gradient region at ρ∼0.6. From the measurement of the averaged peak energy intensity using the soft X-ray CCD camera it is confirmed that the impurity confinement is also improved with N-ITB. The radial electric field is observed to bifurcate into electron root (E r ∼15kV/m) and rather large electric field shear (dE r /dr∼-300kV/m 2 ) is produced in the layer between ion and electron root. (author)
Increased understanding of neoclassical internal transport barrier on CHS
International Nuclear Information System (INIS)
Minami, T.
2002-01-01
The recent progress of the study on neoclassical internal transport barrier (N-ITB) of Compact Helical System (CHS) is reported. This barrier is formed due to the positive electric field and the electric field shear that are created by bifurcation of radial electric field with the electron cyclotron (EC) heating on helical devices. Previously N-ITB was observed for ECH plasma, recently N-ITB barrier was also observed for EC (53.2 GHz 2nd harmonic) heated NBI plasma. The N-ITB of EC heated NBI plasma is formed at the outer location (r/a=0.4-0.6) in comparison with that (r/a=0.3) of ECH plasma, so that the improved confinement region is expanded. The improvement in the ion energy transport is also observed and the ion temperature is increased up to 400 eV along with the electron temperature, that is two times higher than that of the plasma without N-ITB. The particle transport is studied by measuring the peak energy of Titanium Kα line intensity with the soft X-ray CCD camera. The energy is shifted from 4.68 kV to 4.73 kV by forming N-ITB. The improvement of the impurity transport has been confirmed inside N-ITB by comparing the experimental result with the MIST code. (author)
Theory for neoclassical toroidal plasma viscosity in tokamaks
International Nuclear Information System (INIS)
Shaing, K C; Chu, M S; Hsu, C T; Sabbagh, S A; Seol, Jae Chun; Sun, Y
2012-01-01
Error fields and magnetohydrodynamic modes break toroidal symmetry in tokamaks. The broken symmetry enhances the toroidal plasma viscosity, which results in a steady-state toroidal plasma flow. A theory for neoclassical toroidal plasma viscosity in the low-collisionality regimes is developed. It extends stellarator transport theory to include multiple modes and to allow for |m − nq| ∼ 1. Here, m is the poloidal mode number, n is the toroidal mode number and q is the safety factor. The bounce averaged drift kinetic equation is solved in several asymptotic limits to obtain transport fluxes. These fluxes depend non-linearly on the radial electric field except for those in the 1/ν regime. Here, ν is the collision frequency. The theory is refined to include the effects of the superbanana plateau resonance at the phase space boundary and the finite ∇B drift on the collisional boundary layer fluxes. Analytical expressions that connect all asymptotic limits are constructed and are in good agreement with the numerical results. The flux–force relations that relate transport fluxes to forces are used to illustrate the roles of transport fluxes in the momentum equation. It is shown that the ambipolar state is reached when the momentum equation is relaxed. It is also shown that the origin of the momentum for plasma flow generated without momentum sources is the local unbalance of particles' momenta and is diamagnetic in nature regardless of the details of the theory. (paper)
Directory of Open Access Journals (Sweden)
Andrew M. Parker
2007-12-01
Full Text Available Our previous research suggests that people reporting a stronger desire to maximize obtain worse life outcomes (Bruine de Bruin et al., 2007. Here, we examine whether this finding may be explained by the decision-making styles of self-reported maximizers. Expanding on Schwartz et al. (2002, we find that self-reported maximizers are more likely to show problematic decision-making styles, as evidenced by self-reports of less behavioral coping, greater dependence on others when making decisions, more avoidance of decision making, and greater tendency to experience regret. Contrary to predictions, self-reported maximizers were more likely to report spontaneous decision making. However, the relationship between self-reported maximizing and worse life outcomes is largely unaffected by controls for measures of other decision-making styles, decision-making competence, and demographic variables.
FELICIA RAMONA BIRAU
2012-01-01
In this article, the concept of capital market is analysed using Fractal Market Hypothesis which is a modern, complex and unconventional alternative to classical finance methods. Fractal Market Hypothesis is in sharp opposition to Efficient Market Hypothesis and it explores the application of chaos theory and fractal geometry to finance. Fractal Market Hypothesis is based on certain assumption. Thus, it is emphasized that investors did not react immediately to the information they receive and...
Hyman Minsky's financial instability hypothesis and the Greek debt crisis
Directory of Open Access Journals (Sweden)
Sergey Beshenov
2015-12-01
Full Text Available This article attempts to analyze the current debt crisis in Greece based on the financial instability hypothesis developed by Hyman Minsky. This article shows that the hypothesis provides an understanding of how an economy endogenously becomes “financially fragile” and thus prone to crises. The authors analyze how public and private sector behavior in the Greek economy led to the country's debt crisis. In particular, based on a sample of 36 Greek companies, the authors show that between 2001 and 2014, the majority of those companies had switched to fragile financial structures. Special attention is devoted to the negative consequences of applying the neoclassical doctrine of “austerity measures” in Greece as the principal “anti-crisis” concept of mainstream economic science.
Variability: A Pernicious Hypothesis.
Noddings, Nel
1992-01-01
The hypothesis of greater male variability in test results is discussed in its historical context, and reasons feminists have objected to the hypothesis are considered. The hypothesis acquires political importance if it is considered that variability results from biological, rather than cultural, differences. (SLD)
2009-06-01
Existing models of Neoclassical Realism, however, leave analysts to choose intervening traits in an ad hoc manner. This limits the theorys usefulness... Neoclassical Realism and the generalized intervening variable model developed in this thesis show usefulness beyond existing single- or multi-level theories ...weaknesses. Then, it proposes Neoclassical Realism, a modification of Realism, as an international relations theory that provides a useful model for foreign
Insulin resistance and maximal oxygen uptake
DEFF Research Database (Denmark)
Seibaek, Marie; Vestergaard, Henrik; Burchardt, Hans
2003-01-01
BACKGROUND: Type 2 diabetes, coronary atherosclerosis, and physical fitness all correlate with insulin resistance, but the relative importance of each component is unknown. HYPOTHESIS: This study was undertaken to determine the relationship between insulin resistance, maximal oxygen uptake......, and the presence of either diabetes or ischemic heart disease. METHODS: The study population comprised 33 patients with and without diabetes and ischemic heart disease. Insulin resistance was measured by a hyperinsulinemic euglycemic clamp; maximal oxygen uptake was measured during a bicycle exercise test. RESULTS......: There was a strong correlation between maximal oxygen uptake and insulin-stimulated glucose uptake (r = 0.7, p = 0.001), and maximal oxygen uptake was the only factor of importance for determining insulin sensitivity in a model, which also included the presence of diabetes and ischemic heart disease. CONCLUSION...
Directory of Open Access Journals (Sweden)
FELICIA RAMONA BIRAU
2012-05-01
Full Text Available In this article, the concept of capital market is analysed using Fractal Market Hypothesis which is a modern, complex and unconventional alternative to classical finance methods. Fractal Market Hypothesis is in sharp opposition to Efficient Market Hypothesis and it explores the application of chaos theory and fractal geometry to finance. Fractal Market Hypothesis is based on certain assumption. Thus, it is emphasized that investors did not react immediately to the information they receive and of course, the manner in which they interpret that information may be different. Also, Fractal Market Hypothesis refers to the way that liquidity and investment horizons influence the behaviour of financial investors.
International Nuclear Information System (INIS)
Gronau, M.
1984-01-01
Two ambiguities are noted in the definition of the concept of maximal CP violation. The phase convention ambiguity is overcome by introducing a CP violating phase in the quark mixing matrix U which is invariant under rephasing transformations. The second ambiguity, related to the parametrization of U, is resolved by finding a single empirically viable definition of maximal CP violation when assuming that U does not single out one generation. Considerable improvement in the calculation of nonleptonic weak amplitudes is required to test the conjecture of maximal CP violation. 21 references
Modeling of Neoclassical Tearing Mode Stability for Generalized Toroidal Geometry
International Nuclear Information System (INIS)
A.L. Rosenberg; D.A. Gates; A. Pletzer; J.E. Menard; S.E. Kruger; C.C. Hegna; F. Paoletti; S. Sabbagh
2002-01-01
Neoclassical tearing modes (NTMs) can lead to disruption and loss of confinement. Previous analysis of these modes used large aspect ratio, low beta (plasma pressure/magnetic pressure) approximations to determine the effect of NTMs on tokamak plasmas. A more accurate tool is needed to predict the onset of these instabilities. As a follow-up to recent theoretical work, a code has been written which computes the tearing mode island growth rate for arbitrary tokamak geometry. It calls PEST-3 [A. Pletzer et al., J. Comput. Phys. 115, 530 (1994)] to compute delta prime, the resistive magnetohydrodynamic (MHD) matching parameter. The code also calls the FLUXGRID routines in NIMROD [A.H. Glasser et al., Plasma Phys. Controlled Fusion 41, A747 (1999)] for Dnc, DI and DR [C.C. Hegna, Phys. Plasmas 6, 3980 (1999); A.H. Glasser et al., Phys. Fluids 18, 875 (1975)], which are the bootstrap current driven term and the ideal and resistive interchange mode criterion, respectively. In addition to these components, the NIMROD routines calculate alphas-H, a new correction to the Pfirsch-Schlter term. Finite parallel transport effects were added and a National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] equilibrium was analyzed. Another program takes the output of PEST-3 and allows the user to specify the rational surface, island width, and amount of detail near the perturbed surface to visualize the total helical flux. The results of this work will determine the stability of NTMs in an spherical torus (ST) [Y.-K.M. Peng et al., Nucl. Fusion 26, 769 (1986)] plasma with greater accuracy than previously achieved
Energy Technology Data Exchange (ETDEWEB)
Sousa, Tania; Domingos, Tiago [Environment and Energy Section, DEM, Instituto Superior Tecnico, Avenida Rovisco Pais, 1, 1049-001 Lisboa (Portugal)
2006-06-10
The relation between Thermodynamics and Economics is a paramount issue in Ecological Economics. Two different levels can be distinguished when discussing it: formal and substantive. At the formal level, a mathematical framework is used to describe both thermodynamic and economic systems. At the substantive level, thermodynamic laws are applied to economic processes. In Ecological Economics, there is a widespread claim that neoclassical economics has the same mathematical formulation as classical mechanics and is therefore fundamentally flawed because: (1) utility does not obey a conservation law as energy does; (2) an equilibrium theory cannot be used to study irreversible processes. Here, we show that neoclassical economics is based on a wrong formulation of classical mechanics, being in fact formally analogous to equilibrium thermodynamics. The similarity between both formalisms, namely that they are both cases of constrained optimisation, is easily perceived when thermodynamics is looked upon using the Tisza-Callen axiomatisation. In this paper, we take the formal analogy between equilibrium thermodynamics and economic systems far enough to answer the formal criticisms, proving that the formalism of neoclassical economics has irreversibility embedded in it. However, the formal similarity between equilibrium thermodynamics and neoclassical microeconomics does not mean that economic models are in accordance with mass, energy and entropy balance equations. In fact, neoclassical theory suffers from flaws in the substantive integration with thermodynamic laws as has already been fully demonstrated by valuable work done by ecological economists in this field. (author)
Neoclassical simulation of tokamak plasmas using the continuum gyrokinetic code TEMPEST.
Xu, X Q
2008-07-01
We present gyrokinetic neoclassical simulations of tokamak plasmas with a self-consistent electric field using a fully nonlinear (full- f ) continuum code TEMPEST in a circular geometry. A set of gyrokinetic equations are discretized on a five-dimensional computational grid in phase space. The present implementation is a method of lines approach where the phase-space derivatives are discretized with finite differences, and implicit backward differencing formulas are used to advance the system in time. The fully nonlinear Boltzmann model is used for electrons. The neoclassical electric field is obtained by solving the gyrokinetic Poisson equation with self-consistent poloidal variation. With a four-dimensional (psi,theta,micro) version of the TEMPEST code, we compute the radial particle and heat fluxes, the geodesic-acoustic mode, and the development of the neoclassical electric field, which we compare with neoclassical theory using a Lorentz collision model. The present work provides a numerical scheme for self-consistently studying important dynamical aspects of neoclassical transport and electric field in toroidal magnetic fusion devices.
Testing neoclassical and turbulent effects on poloidal rotation in the core of DIII-D
Energy Technology Data Exchange (ETDEWEB)
Chrystal, C. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Burrell, K. H.; Staebler, G. M.; Kinsey, J. E.; Lao, L. L.; Grassie, J. S. de [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Grierson, B. A.; Solomon, W. M.; Wang, W. X. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Rhodes, T. L.; Schmitz, L. [University of California Los Angeles, P.O. Box 957099, Los Angeles, California 90095-7099 (United States); Mordijck, S. [College of William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795 (United States); Meneghini, O. [Oak Ridge Associated Universities, 1299 Bethel Valley Rd, Bldg SC-200, Oak Ridge, Tennessee 37830 (United States)
2014-07-15
Experimental tests of ion poloidal rotation theories have been performed on DIII-D using a novel impurity poloidal rotation diagnostic. These tests show significant disagreements with theoretical predictions in various conditions, including L-mode plasmas with internal transport barriers (ITB), H-mode plasmas, and QH-mode plasmas. The theories tested include standard neoclassical theory, turbulence driven Reynolds stress, and fast-ion friction on the thermal ions. Poloidal rotation is observed to spin up at the formation of an ITB and makes a significant contribution to the measurement of the E{sup →}×B{sup →} shear that forms the ITB. In ITB cases, neoclassical theory agrees quantitatively with the experimental measurements only in the steep gradient region. Significant quantitative disagreement with neoclassical predictions is seen in the cores of ITB, QH-, and H-mode plasmas, demonstrating that neoclassical theory is an incomplete description of poloidal rotation. The addition of turbulence driven Reynolds stress does not remedy this disagreement; linear stability calculations and Doppler backscattering measurements show that disagreement increases as turbulence levels decline. Furthermore, the effect of fast-ion friction, by itself, does not lead to improved agreement; in QH-mode plasmas, neoclassical predictions are closest to experimental results in plasmas with the largest fast ion friction. Predictions from a new model that combines all three effects show somewhat better agreement in the H-mode case, but discrepancies well outside the experimental error bars remain.
Testing neoclassical and turbulent effects on poloidal rotation in the core of DIII-D
International Nuclear Information System (INIS)
Chrystal, C.; Burrell, K. H.; Staebler, G. M.; Kinsey, J. E.; Lao, L. L.; Grassie, J. S. de; Grierson, B. A.; Solomon, W. M.; Wang, W. X.; Rhodes, T. L.; Schmitz, L.; Mordijck, S.; Meneghini, O.
2014-01-01
Experimental tests of ion poloidal rotation theories have been performed on DIII-D using a novel impurity poloidal rotation diagnostic. These tests show significant disagreements with theoretical predictions in various conditions, including L-mode plasmas with internal transport barriers (ITB), H-mode plasmas, and QH-mode plasmas. The theories tested include standard neoclassical theory, turbulence driven Reynolds stress, and fast-ion friction on the thermal ions. Poloidal rotation is observed to spin up at the formation of an ITB and makes a significant contribution to the measurement of the E → ×B → shear that forms the ITB. In ITB cases, neoclassical theory agrees quantitatively with the experimental measurements only in the steep gradient region. Significant quantitative disagreement with neoclassical predictions is seen in the cores of ITB, QH-, and H-mode plasmas, demonstrating that neoclassical theory is an incomplete description of poloidal rotation. The addition of turbulence driven Reynolds stress does not remedy this disagreement; linear stability calculations and Doppler backscattering measurements show that disagreement increases as turbulence levels decline. Furthermore, the effect of fast-ion friction, by itself, does not lead to improved agreement; in QH-mode plasmas, neoclassical predictions are closest to experimental results in plasmas with the largest fast ion friction. Predictions from a new model that combines all three effects show somewhat better agreement in the H-mode case, but discrepancies well outside the experimental error bars remain
Finite-orbit-width effect and the radial electric field in neoclassical transport phenomena
International Nuclear Information System (INIS)
Satake, S.; Okamoto, M.; Nakajima, N.; Sugama, H.; Yokoyama, M.; Beidler, C.D.
2005-01-01
Modeling and detailed simulation of neoclassical transport phenomena both in 2D and 3D toroidal configurations are shown. The emphasis is put on the effect of finiteness of the drift-orbit width, which brings a non-local nature to neoclassical transport phenomena. Evolution of the self-consistent radial electric field in the framework of neoclassical transport is also investigated. The combination of Monte-Carlo calculation for ion transport and numerical solver of ripple-averaged kinetic equation for electrons makes it possible to calculate neoclassical fluxes and the time evolution of the radial electric field in the whole plasma region, including the finite-orbit-width (FOW) effects and global evolution of geodesic acoustic mode (GAM). The simulation results show that the heat conductivity around the magnetic axis is smaller than that obtained from standard neoclassical theory and that the evolution of GAM oscillation on each flux surface is coupled with other surfaces if the FOW effect is significant. A global simulation of radial electric field evolution in a non-axisymmetric plasma is also shown. (author)
Extended numerical modeling of impurity neoclassical transport in tokamak edge plasmas
International Nuclear Information System (INIS)
Inoue, H.; Yamoto, S.; Hatayama, A.; Homma, Y.
2016-01-01
Understanding of impurity transport in tokamaks is an important issue in order to reduce the impurity contamination in fusion core plasmas. Recently, a new kinetic numerical scheme of impurity classical/neoclassical transport has been developed. This numerical scheme makes it possible to include classical self-diffusion (CL SD), classical inward pinch (CL IWP), and classical temperature screening effect (CL TSE) of impurity ions. However, impurity neoclassical transport has been modeled only in the case where background plasmas are in the Pfirsch-Schluter (PS) regime. The purpose of this study is to extend our previous model to wider range of collisionality regimes, i.e., not only the PS regime, but also the plateau regime. As in the previous study, a kinetic model with Binary Collision Monte-Carlo Model (BMC) has been adopted. We focus on the modeling of the neoclassical self-diffusion (NC SD) and the neoclassical inward pinch (NC IWP). In order to simulate the neoclassical transport with the BCM, velocity distribution of background plasma ions has been modeled as a deformed Maxwell distribution which includes plasma density gradient. Some test simulations have been done. As for NC SD of impurity ions, our scheme reproduces the dependence on the collisionality parameter in wide range of collisionality regime. As for NC IWP, in cases where test impurity ions and background ions are in the PS and plateau regimes, parameter dependences have been reproduced. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
International Nuclear Information System (INIS)
Tanaka, K.; Michael, C.; Vyacheslavov, L.N.
2008-01-01
Density profiles in LHD were measured and particle transport coefficients were estimated from density modulation experiments in LHD. The data set contains the wide region of discharge condition. The dataset of different magnetic axis, toroidal magnetic field and heating power provided data set of widely scanned neoclassical transport. At minimized neoclassical transport configuration in the dataset (Rax=3.5m, Bt=2.8T) showed peaked density profile. Its peaking factor increased gradually with decrease of collisional frequency. This is a similar result observed in tokamak data base. At other configuration, peaking factor reduced with decrease of collisional frequency. Data set showed that larger contribution of neoclassical transport produced hollowed density profile. Comparison between neoclassical and experimental estimated particle diffusivity showed different minimum condition. This suggests neoclassical optimization is not same as anomalous optimization. Clear difference of spatial profile of turbulence was observed between hollowed and peaked density profiles. Major part of fluctuation existed in the unstable region of linear growth rate of ion temperature gradient mode. (author)
Computational modeling of neoclassical and resistive magnetohydrodynamic tearing modes in tokamaks
International Nuclear Information System (INIS)
Gianakon, T.A.; Hegna, C.C.; Callen, J.D.
1996-01-01
Numerical studies of the nonlinear evolution of magnetohydrodynamic-type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion of neoclassical physics introduces an additional free-energy source for the nonlinear formation of magnetic islands through the effects of a bootstrap current in Ohm close-quote s law. The neoclassical tearing mode is demonstrated to be destabilized in plasmas which are otherwise Δ' stable, albeit once an island width threshold is exceeded. The plasma pressure dynamics and neoclassical tearing growth is shown to be sensitive to the choice of the ratio of the parallel to perpendicular diffusivity (χ parallel /χ perpendicular ). The study is completed with a demonstration and theoretical comparison of the threshold for single helicity neoclassical magnetohydrodynamic tearing modes, which is described based on parameter scans of the local pressure gradient, the ratio of perpendicular to parallel pressure diffusivities χ perpendicular /χ parallel , and the magnitude of an initial seed magnetic perturbation. copyright 1996 American Institute of Physics
Extended numerical modeling of impurity neoclassical transport in tokamak edge plasmas
Energy Technology Data Exchange (ETDEWEB)
Inoue, H.; Yamoto, S.; Hatayama, A. [Graduate School of Science and Technology, Keio University, Hiyoshi, Yokohama (Japan); Homma, Y. [Graduate School of Science and Technology, Keio University, Hiyoshi, Yokohama (Japan); Research Fellow of Japan Society for the Promotion of Science, Tokyo (Japan)
2016-08-15
Understanding of impurity transport in tokamaks is an important issue in order to reduce the impurity contamination in fusion core plasmas. Recently, a new kinetic numerical scheme of impurity classical/neoclassical transport has been developed. This numerical scheme makes it possible to include classical self-diffusion (CL SD), classical inward pinch (CL IWP), and classical temperature screening effect (CL TSE) of impurity ions. However, impurity neoclassical transport has been modeled only in the case where background plasmas are in the Pfirsch-Schluter (PS) regime. The purpose of this study is to extend our previous model to wider range of collisionality regimes, i.e., not only the PS regime, but also the plateau regime. As in the previous study, a kinetic model with Binary Collision Monte-Carlo Model (BMC) has been adopted. We focus on the modeling of the neoclassical self-diffusion (NC SD) and the neoclassical inward pinch (NC IWP). In order to simulate the neoclassical transport with the BCM, velocity distribution of background plasma ions has been modeled as a deformed Maxwell distribution which includes plasma density gradient. Some test simulations have been done. As for NC SD of impurity ions, our scheme reproduces the dependence on the collisionality parameter in wide range of collisionality regime. As for NC IWP, in cases where test impurity ions and background ions are in the PS and plateau regimes, parameter dependences have been reproduced. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Physiopathological Hypothesis of Cellulite
de Godoy, José Maria Pereira; de Godoy, Maria de Fátima Guerreiro
2009-01-01
A series of questions are asked concerning this condition including as regards to its name, the consensus about the histopathological findings, physiological hypothesis and treatment of the disease. We established a hypothesis for cellulite and confirmed that the clinical response is compatible with this hypothesis. Hence this novel approach brings a modern physiological concept with physiopathologic basis and clinical proof of the hypothesis. We emphasize that the choice of patient, correct diagnosis of cellulite and the technique employed are fundamental to success. PMID:19756187
Life Origination Hydrate Hypothesis (LOH-Hypothesis
Directory of Open Access Journals (Sweden)
Victor Ostrovskii
2012-01-01
Full Text Available The paper develops the Life Origination Hydrate Hypothesis (LOH-hypothesis, according to which living-matter simplest elements (LMSEs, which are N-bases, riboses, nucleosides, nucleotides, DNA- and RNA-like molecules, amino-acids, and proto-cells repeatedly originated on the basis of thermodynamically controlled, natural, and inevitable processes governed by universal physical and chemical laws from CH4, niters, and phosphates under the Earth's surface or seabed within the crystal cavities of the honeycomb methane-hydrate structure at low temperatures; the chemical processes passed slowly through all successive chemical steps in the direction that is determined by a gradual decrease in the Gibbs free energy of reacting systems. The hypothesis formulation method is based on the thermodynamic directedness of natural movement and consists ofan attempt to mentally backtrack on the progression of nature and thus reveal principal milestones alongits route. The changes in Gibbs free energy are estimated for different steps of the living-matter origination process; special attention is paid to the processes of proto-cell formation. Just the occurrence of the gas-hydrate periodic honeycomb matrix filled with LMSEs almost completely in its final state accounts for size limitation in the DNA functional groups and the nonrandom location of N-bases in the DNA chains. The slowness of the low-temperature chemical transformations and their “thermodynamic front” guide the gross process of living matter origination and its successive steps. It is shown that the hypothesis is thermodynamically justified and testable and that many observed natural phenomena count in its favor.
Neoclassical economic orthodoxy and the need for a new post-crisis economic paradigm
Directory of Open Access Journals (Sweden)
Andrei JOSAN
2013-08-01
Full Text Available Capitalism is a social adaptive system that evolve, change and grow in response to the challenges of a rapidly changing economic environment. When capitalism is seriously threatened by a systemic crisis, a new version much better adapted to existing conditions appears. Critical analysis of the fundamental ideas underlying neoclassical economic theory shows that the capitalist system is fundamentally a dynamic and therefore static neoclassical models proved to be unsuitable for studying it. Contrary to neoclassical economic vision, the capitalist economy is not governed by immutable economic laws. Global systemic crisis of capitalism that began in 2007 has highlighted the need for a new economic paradigm on which to be built and to be performed a new version of capitalism, in line with the increasingly complex realities of a globalized and quick changing world.
Lagrangian neoclassical transport theory applied to the region near the magnetic axis
Energy Technology Data Exchange (ETDEWEB)
Satake, Shinsuke [The Graduate Univ. for Advanced Studies, Dept. of Fusion Science, Toki, Gifu (Japan); Okamoto, Masao; Sugama, Hideo [National Inst. for Fusion Science, Toki, Gifu (Japan)
2002-06-01
Neoclassical transport theory around the magnetic axis of a tokamak is studied, in which relatively wide ''potato'' orbits play an important role in transport. Lagrangian formulation of transport theory, which has been investigated to reflect finiteness of guiding-center orbit widths to transport equations, is developed in order to analyze neoclassical transport near the axis for a low-collisionality plasma. The treatment of self-collision term in Lagrangian formulation is revised to retain momentum conservation property of it. With directly reflecting the orbital properties of all the types of orbits in calculation, the ion thermal conductivity around the axis is found to decrease than from that predicted by conventional neoclassical theory. This result supports recent numerical simulations which show the reduction of thermal conductivity near the magnetic axis. (author)
Time dependent plasma viscosity and relation between neoclassical transport and turbulent transport
International Nuclear Information System (INIS)
Shaing, K.C.
2005-01-01
Time dependent plasma viscosities for asymmetric toroidal plasmas in various collisionality regimes are calculated. It is known that in the symmetric limit the time dependent plasma viscosities accurately describe plasma flow damping rate. Thus, time dependent plasma viscosities are important in modeling the radial electric field of the zonal flow. From the momentum balance equation, it is shown that, at the steady state, the balance of the viscosity force and the momentum source determines the radial electric field of the zonal flow. Thus, for a fixed source, the smaller the viscous force is, the larger the value of the radial electric field is, which in turn suppresses the turbulence fluctuations more and improves turbulence transport. However, the smaller the viscous force also implies the smaller the neoclassical transport fluxes based on the neoclassical flux-force relationship. We thus show that when neoclassical transport fluxes are improved so are the turbulent fluxes in toroidal plasmas. (author)
Neoclassical kinetic theory near the edge of a diverted tokamak plasma
International Nuclear Information System (INIS)
Solano, E.R.; Hazeltine, R.D.
1993-01-01
In a diverted plasma, the poloidal magnetic field has a strong poloidal variation, approaching zero near the X-point. Typically, neoclassical theory is based on ordering assumptions about the 3 characteristic frequencies present in the problem: streaming, collisions and drift. In a circular geometry, the streaming freuency is constant, while the drift frequency has a sin(θ) variation. In a shaped plasma, the streaming frequency also has a poloidal variation. The ordering is now established by the amplitude of these frequencies. With a model poloidal flux function, the authors solve the drift kinetic equation inside, but near, the separatrix. Both the plateau and collisional regime are considered. Ion rotation rates, and their poloidal variation, are calculated. It is shown that the standard neoclassical rotation predictions still hold, when correctly interpreted. Other neoclassical fluxes are calculated as well
Lagrangian neoclassical transport theory applied to the region near the magnetic axis
International Nuclear Information System (INIS)
Satake, Shinsuke; Okamoto, Masao; Sugama, Hideo
2002-01-01
Neoclassical transport theory around the magnetic axis of a tokamak is studied, in which relatively wide 'potato' orbits play an important role in transport. Lagrangian formulation of transport theory, which has been investigated to reflect finiteness of guiding-center orbit widths to transport equations, is developed in order to analyze neoclassical transport near the axis for a low-collisionality plasma. The treatment of self-collision term in Lagrangian formulation is revised to retain momentum conservation property of it. By directly reflecting the orbital properties of all the types of orbits in calculation, the ion thermal conductivity around the axis is found to decrease from that predicted by conventional neoclassical theory. This result supports recent numerical simulations which show the reduction of thermal conductivity near the magnetic axis
International Nuclear Information System (INIS)
Yokoyama, M.; Matsuoka, S.; Funaba, H.; Ida, K.; Nagaoka, K.; Yoshinuma, M.; Takeiri, Y.; Kaneko, O.
2010-01-01
The neoclassical (NC) transport analyses have been performed to elucidate the plausible approaches towards higher ion-temperature heliotron plasmas. Avoidance of the ripple transport is the key issue, for which the neoclassical ambipolar radial electric field (E r ) can be utilized. The ion-root scenario and the electron-root scenario are expected to be effective according to the experimental situation (especially, the temperature ratio between ions and electrons). The impact of the ion mass on the neoclassical ambipolar E r is also investigated to reveal the easier realization of electron-root E r in heavier ion plasmas. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Sawtooth-free Ohmic discharges in ASDEX and the aspects of neoclassical ion transport
International Nuclear Information System (INIS)
Stroth, U.; Fussmann, G.; Krieger, K.; Mertens, V.; Wagner, F.; Bessenrodt-Weberpals, M.; Buechse, R.; Giannone, L.; Herrmann, H.; Simmet, E.; Steuer, K.H.
1991-05-01
Sawtooth-free Ohmic discharges can serve as a model case for a quiescent Tokamak plasma. We report on the properties and the global parameters of these discharges observed in ASDEX and make comments on the mechanism which seems to be responsible for the stabilization of the sawtooth instability. Stationary Ohmic discharge were used to investigate particle, impurity and energy transport in the absence of the sawtooth instability. Particular emphasis has been devoted to a comparison with the predictions of neoclassical theories. We find that the ion energy transport is on the level predicted by neoclassical theory and can explain particle and impurity transport with neoclassical inward drift velocities and diffusion coefficients with the same small anomalous contribution. In the central region of the plasma, where the power flux is low, very small values were found for the electron heat conductivity. (orig.)
Neoclassical and anomalous transport in axisymmetric toroidal plasmas with electrostatic turbulence
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1995-05-01
Neoclassical and anomalous transport fluxes are determined for axisymmetric toroidal plasmas with weak electrostatic fluctuations. The neoclassical and anomalous fluxes are defined based on the ensemble-averaged kinetic equation with the statistically averaged nonlinear term. The anomalous forces derived from that quasilinear term induce the anomalous particle and heat fluxes. The neoclassical banana-plateau particle and heat fluxes and the bootstrap current are also affected by the fluctuations through the parallel anomalous forces and the modified parallel viscosities. The quasilinear term, the anomalous forces, and the anomalous particle and heat fluxes are evaluated from the fluctuating part of the drift kinetic equation. The averaged drift kinetic equation with the quasilinear term is solved for the plateau regime to derive the parallel viscosities modified by the fluctuations. The entropy production rate due to the anomalous transport processes is formulated and used to identify conjugate pairs of the anomalous fluxes and forces, which are connected by the matrix with the Onsager symmetry. (author)
Slowing down tail enhanced, neoclassical and classical alpha particle fluxes in tokamak reactors
International Nuclear Information System (INIS)
Catto, P.J.; Tessarotto, M.
1988-01-01
The classical and neoclassical particle and energy fluxes associated with a slowing down tail, alpha particle distribution function are evaluated for arbitrary aspect ratio ε -1 , cross section, and poloidal magnetic field. The retention of both electron and ion drag and pitch angle scattering by the background ions results in a large diffusive neoclassical heat flux in the plasma core. This flux remains substantial at larger radii only if the characteristic speed associated with pitch angle scattering, v/sub b/, is close enough to the alpha birth speed v 0 so that ε(v 0 /v/sub b/) 3 remains less than some order unity critical value which is not determined by the methods herein. The enhanced neoclassical losses would only have a serious impact on ignition if the critical value of ε(v 0 /v/sub b/) 3 is found to be somewhat larger than unity
Lagrangian neoclassical transport theory applied to the region near the magnetic axis
International Nuclear Information System (INIS)
Satake, Shinsuke; Okamoto, Masao; Sugama, Hideo
2002-06-01
Neoclassical transport theory around the magnetic axis of a tokamak is studied, in which relatively wide ''potato'' orbits play an important role in transport. Lagrangian formulation of transport theory, which has been investigated to reflect finiteness of guiding-center orbit widths to transport equations, is developed in order to analyze neoclassical transport near the axis for a low-collisionality plasma. The treatment of self-collision term in Lagrangian formulation is revised to retain momentum conservation property of it. With directly reflecting the orbital properties of all the types of orbits in calculation, the ion thermal conductivity around the axis is found to decrease than from that predicted by conventional neoclassical theory. This result supports recent numerical simulations which show the reduction of thermal conductivity near the magnetic axis. (author)
Kinetic simulations of neoclassical and anomalous transport processes in helical systems
International Nuclear Information System (INIS)
Sugama, Hideo; Watanabe, Tomohiko; Nunami, Masanori; Satake, Shinsuke; Matsuoka, Seikichi; Tanaka, Kenji
2012-01-01
Drift kinetic and gyrokinetic theories and simulations are powerful means for quantitative predictions of neoclassical and anomalous transport fluxes in helical systems such as the Large Helical Device (LHD). The δf Monte Carlo particle simulation code, FORTEC-3D, is used to predict radial profiles of the neoclassical particle and heat transport fluxes and the radial electric field in helical systems. The radial electric field profiles in the LHD plasmas are calculated from the ambipolarity condition for the neoclassical particle fluxes obtained by the global simulations using the FORTEC-3D code, in which effects of ion or electron finite orbit widths are included. Gyrokinetic Vlasov simulations using the GKV code verify the theoretical prediction that the neoclassical optimization of helical magnetic configuration enhances the zonal flow generation which leads to the reduction of the turbulent heat diffusivity χ i due to the ion temperature gradient (ITG) turbulence. Comparisons between results for the high ion temperature LHD experiment and the gyrokinetic simulations using the GKV-X code show that the χ i profile and the poloidal wave number spectrum of the density fluctuation obtained from the simulations are in reasonable agreements with the experimental results. It is predicted theoretically and confirmed by the linear GKV simulations that the E × B rotation due to the background radial electric field E r can enhance the zonal-flow response to a given source. Thus, in helical systems, the turbulent transport is linked to the neoclassical transport through E r which is determined from the ambipolar condition for neoclassical particle fluxes and influences the zonal flow generation leading to reduction of the turbulent transport. In order to investigate the E r effect on the regulation of the turbulent transport by the zonal flow generation, the flux-tube bundle model is proposed as a new method for multiscale gyrokinetic simulations. (author)
Breton, S.; Casson, F. J.; Bourdelle, C.; Angioni, C.; Belli, E.; Camenen, Y.; Citrin, J.; Garbet, X.; Sarazin, Y.; Sertoli, M.; JET Contributors
2018-01-01
Heavy impurities, such as tungsten (W), can exhibit strongly poloidally asymmetric density profiles in rotating or radio frequency heated plasmas. In the metallic environment of JET, the poloidal asymmetry of tungsten enhances its neoclassical transport up to an order of magnitude, so that neoclassical convection dominates over turbulent transport in the core. Accounting for asymmetries in neoclassical transport is hence necessary in the integrated modeling framework. The neoclassical drift kinetic code, NEO [E. Belli and J. Candy, Plasma Phys. Controlled Fusion P50, 095010 (2008)], includes the impact of poloidal asymmetries on W transport. However, the computational cost required to run NEO slows down significantly integrated modeling. A previous analytical formulation to describe heavy impurity neoclassical transport in the presence of poloidal asymmetries in specific collisional regimes [C. Angioni and P. Helander, Plasma Phys. Controlled Fusion 56, 124001 (2014)] is compared in this work to numerical results from NEO. Within the domain of validity of the formula, the factor for reducing the temperature screening due to poloidal asymmetries had to be empirically adjusted. After adjustment, the modified formula can reproduce NEO results outside of its definition domain, with some limitations: When main ions are in the banana regime, the formula reproduces NEO results whatever the collisionality regime of impurities, provided that the poloidal asymmetry is not too large. However, for very strong poloidal asymmetries, agreement requires impurities in the Pfirsch-Schlüter regime. Within the JETTO integrated transport code, the analytical formula combined with the poloidally symmetric neoclassical code NCLASS [W. A. Houlberg et al., Phys. Plasmas 4, 3230 (1997)] predicts the same tungsten profile as NEO in certain cases, while saving a factor of one thousand in computer time, which can be useful in scoping studies. The parametric dependencies of the temperature
Neoclassical transport coefficients for tokamaks with bean-shaped flux surfaces
International Nuclear Information System (INIS)
Chang, C.S.; Kaye, S.M.
1990-11-01
Simple analytic representations of the neoclassical transport coefficients for indented flux surfaces are presented. It is shown that a transport coefficient for an indented flux surface can be expressed in terms of a linear combination of the previously known transport coefficients for two nonindented flux surfaces. Numerical calculations based on actual equilibria from the PBX-M tokamak indicate that, even for modestly indented flux surfaces, the ion neoclassical thermal transport can be over a factor of two smaller than in a circular plasma with the same midplane radius or with the equivalent areas. 6 refs., 5 figs., 1 tab
First observation of neoclassical tearing modes in the HL-2A tokamak
International Nuclear Information System (INIS)
Ji Xiaoquan; Yang Qingwei; Liu Yi; Zhou Jun; Feng Beibin; Yuan Baoshan
2010-01-01
The m/n=2/1 neoclassical tearing modes are first observed in HL-2A low density, low beta plasma with central electron cyclotron resonance heating. The neoclassical tearing modes (NTMs) are triggered by a sawtooth crash with m/n=1/1 precursors, which are toroidal coupled with a small scale m/n=2/1 mode. The time history of the island width is compared with the prediction of the NTM theory, showing a good agreement between theory and experiment. (authors)
International Nuclear Information System (INIS)
Kiviniemi, T.
2001-01-01
One of the principal problems en route to a fusion reactor is that of insufficient plasma confinement, which has lead to both theoretical and experimental research into transport processes in the parameter range relevant for fusion energy production. The neoclassical theory of tokamak transport is well-established unlike the theory of turbulence driven anomalous transport in which extensive progress has been made during last few years. So far, anomalous transport has been dominant in experiments, but transport may be reduced to the neoclassical level in advanced tokamak scenarios. This thesis reports a numerical study of neoclassical fluxes, parallel viscosity, and neoclassical radial current balance in tokamaks. Neoclassical parallel viscosity and particle fluxes are simulated over a wide range of collisionalities, using the fully kinetic five-dimensional neoclassical orbit-following Monte Carlo code ASCOT. The qualitative behavior of parallel viscosity derived in earlier analytic models is shown to be incorrect for high poloidal Mach numbers. This is because the poloidal dependence of density was neglected. However, in high Mach number regime, it is the convection and compression terms, rather than the parallel viscosity term, that are shown to dominate the momentum balance. For fluxes, a reasonable agreement between numerical and analytical results is found in the collisional parameter regime. Neoclassical particle fluxes are additionally studied in the banana regime using the three-dimensional Fokker-Planck code DEPORA, which solves the drift-kinetic equation with finite differencing. Limitations of the small inverse aspect ratio approximation adopted in the analytic theory are addressed. Assuming that the anomalous transport is ambipolar, the radial electric field and its shear at the tokamak plasma edge can be solved from the neoclassical radial current balance. This is performed both for JET and ASDEX Upgrade tokamaks using the ASCOT code. It is shown that
Directory of Open Access Journals (Sweden)
Robert M. Solow
2000-05-01
Full Text Available The paper surveys the neoclassical theory of growth. As a preliminary, the meaning of the adjective "neoclassical" is discussed. The basic model is then sketched, and the conditions ensuring a stationary state are illustrated. The issue of the convergence to a stationary state (and that of the speed of convergence is further considered. A discussion of "primary factors" opens the way to the "new" theory of growth, with endogenous technical progress. A number of extensions of the basic model are then recalled: two-sector and multi-sectoral models, overlapping generations models, the role of money in growth models.
Effects of electrostatic trapping on neoclassical transport in an impure plasma
International Nuclear Information System (INIS)
Hazeltine, R.D.; Ware, A.A.
1976-01-01
Contamination of a toroidally confined plasma by highly charged impurity ions can produce substantial variation of the electrostatic potential within a magnetic surface. The resulting electrostatic trapping and electrostatic drifts, of hydrogen ions and electrons, yields significant alterations in neoclassical transport theory. A transport theory which includes these effects is derived from the drift-kinetic equation, with an ordering scheme modeled on the parameters of recent tokamak experiments. The theory self-consistently predicts that electrostatic trapping should be fully comparable to magnetic trapping, and provides transport coefficients which, depending quadratically upon the temperature and pressure gradients, differ markedly from the standard neoclassical coefficients for a pure plasma
International Nuclear Information System (INIS)
Kim, Sang-Hoon
2007-01-01
Neoclassical and institutional economics have developed different theories and methodologies for evaluating environmental and social impacts of electricity generation. The neoclassical approach valuates external costs, and the institutional approach uses social cost valuation and MCDM methods. This paper focuses on three dimensions: theoretical and methodological backgrounds; critical review of specific studies: methodologies, results, and limitations; and discussing their results and implications for environmental policy and further research. The two approaches lead to a common conclusion that fossil fuels and nuclear power show the highest environmental impact. Despite the common conclusion, the conclusion has limited implications for environmental policy because of the weakness of their methodologies
DEFF Research Database (Denmark)
Andersen, Klaus Ejner
1985-01-01
Guinea pig maximization tests (GPMT) with chlorocresol were performed to ascertain whether the sensitization rate was affected by minor changes in the Freund's complete adjuvant (FCA) emulsion used. Three types of emulsion were evaluated: the oil phase was mixed with propylene glycol, saline...
Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture
Sanfilippo, Antonio P [Richland, WA; Cowell, Andrew J [Kennewick, WA; Gregory, Michelle L [Richland, WA; Baddeley, Robert L [Richland, WA; Paulson, Patrick R [Pasco, WA; Tratz, Stephen C [Richland, WA; Hohimer, Ryan E [West Richland, WA
2012-03-20
Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture are described according to some aspects. In one aspect, a hypothesis analysis method includes providing a hypothesis, providing an indicator which at least one of supports and refutes the hypothesis, using the indicator, associating evidence with the hypothesis, weighting the association of the evidence with the hypothesis, and using the weighting, providing information regarding the accuracy of the hypothesis.
DEFF Research Database (Denmark)
Mikkelsen, Kaare B.; Kidmose, Preben; Hansen, Lars Kai
2017-01-01
simultaneously recorded scalp EEG. A cross-validation procedure was employed to ensure unbiased estimates. We present several pieces of evidence in support of the keyhole hypothesis: There is a high mutual information between data acquired at scalp electrodes and through the ear-EEG "keyhole," furthermore we......We propose and test the keyhole hypothesis that measurements from low dimensional EEG, such as ear-EEG reflect a broadly distributed set of neural processes. We formulate the keyhole hypothesis in information theoretical terms. The experimental investigation is based on legacy data consisting of 10...
Control of sawteeth and neo-classical tearing modes in tokamaks using electron cyclotron waves
Baar, M.R. de; Bongers, W.A.; Berkel, M. van; Doelman, N.J.; Hennen, B.A.; Nuij, P.; Oosterbeek, J.W.; Steinbuch, M.; Westerhof, E.; Witvoet, G.
2011-01-01
Resistive magneto-hydrodynamic instabilities are expected to limit the performance of nuclear fusion reactors. Prime examples are the sawtooth instability and the neoclassical tearing modes. The sawtooth instability will affect the refueling of the plasma core and the fast particle concentration. In
Neoclassical and Institutional Economics as Foundations for Human Resource Development Theory
Wang, Greg G.; Holton, Elwood F., III
2005-01-01
In an effort to more comprehensively understand economics as a foundation of human resource development (HRD), this article reviews economic theories and models pertinent to HRD research and theory building. By examining neoclassical and neoinstitutional schools of contemporary economics, especially the screening model and the internal labor…
Benchmark test of drift-kinetic and gyrokinetic codes through neoclassical transport simulations
International Nuclear Information System (INIS)
Satake, S.; Sugama, H.; Watanabe, T.-H.; Idomura, Yasuhiro
2009-09-01
Two simulation codes that solve the drift-kinetic or gyrokinetic equation in toroidal plasmas are benchmarked by comparing the simulation results of neoclassical transport. The two codes are the drift-kinetic δf Monte Carlo code (FORTEC-3D) and the gyrokinetic full- f Vlasov code (GT5D), both of which solve radially-global, five-dimensional kinetic equation with including the linear Fokker-Planck collision operator. In a tokamak configuration, neoclassical radial heat flux and the force balance relation, which relates the parallel mean flow with radial electric field and temperature gradient, are compared between these two codes, and their results are also compared with the local neoclassical transport theory. It is found that the simulation results of the two codes coincide very well in a wide rage of plasma collisionality parameter ν * = 0.01 - 10 and also agree with the theoretical estimations. The time evolution of radial electric field and particle flux, and the radial profile of the geodesic acoustic mode frequency also coincide very well. These facts guarantee the capability of GT5D to simulate plasma turbulence transport with including proper neoclassical effects of collisional diffusion and equilibrium radial electric field. (author)
Neoclassical and anomalous transport in toroidal plasmas with drift-ordered turbulence
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1996-01-01
Neoclassical and anomalous transport fluxes are determined for axisymmetric toroidal plasmas with weak electromagnetic drift wave fluctuations. The neoclassical and anomalous fluxes are defined based on the ensemble-averaged kinetic equation with the statistically averaged nonlinear wave-particle interactions. The anomalous forces derived from that quasilinear term induce the anomalous particle and heat fluxes. For the microscale fluctuations k perpendicular ρ i ∼ 1 the parallel neoclassical fluxes remain invariant. For mesoscale fluctuations the mixing length fluctuation level with broken symmetry from (weak) shear flows the neoclassical banana-plateau fluxes are affected by the fluctuations through the parallel anomalous forces and the modified parallel viscosities. The entropy production rate due to the anomalous transport processes is formulated and used to identify conjugate pairs of the anomalous fluxes and forces, which are connected by the matrix with the Onsager symmetry. The proof of the Onsager symmetry is carried out by splitting the response function up into the even and odd parts under the (t, B) → (-t,-B) transformation and using the self-adjointness of the linearized Landau collision operator and the quasilinear formalism. An explicit calculation of the symmetric transport coefficients is possible when the Krook collision model replaces the Landau collision operator. The importance of low aspect ratio tokamaks and helical systems for experimental investigations of the Onsager symmetries is emphasized
Reflection terahertz time-domain imaging for analysis of an 18th century neoclassical easel painting
DEFF Research Database (Denmark)
Dandolo, Corinna Ludovica Koch; Filtenborg, Troels; Fukunaga, Kaori
2015-01-01
Terahertz time-domain imaging (THz-TDI) has been applied for imaging a hidden portrait and other subsurfacecomposition layers of an 18th century (18C) easel painting by Nicolai Abildgaard, the most important 18CDanish neoclassical painter of historical and mythological subjects. For the first time...
Monte Carlo estimation of neoclassical transport for the TJ-II stellarator
International Nuclear Information System (INIS)
Tribaldos, V.
2001-01-01
The neoclassical transport properties of TJ-II stellarator [C. Alejaldre et al., Fusion Technol. 13, 521 (1988)] are studied with the monoenergetic Monte Carlo technique. A compromise between the number of modes and particles and the required computing time to obtain reliable estimates, from the computational point of view, of the monoenergetic diffusion coefficients is shown to be of one thousand particles and one hundred harmonics, because of the rich magnetic-field structure of TJ-II. Although, these requirements are probably too demanding in making the transport estimations. The data base containing the normalized monoenergetic diffusion coefficient for several radial positions, radial electric fields and collisionalities have been fitted using a neural network. This fit reduces the number of points necessary in the data base and allows a smooth interpolation and extrapolation to perform the convolutions of the monoenergetic coefficients with the Maxwellian. For two different typical TJ-II discharges the ambipolar radial electric field, and the neoclassical particle and heat fluxes are presented both showing rather large positive radial electric fields at the plasma core and small negative fields at the edge. The neoclassical particle and energy confinement time are in surprisingly good agreement with the experimental energy balance analysis and the international stellarator scaling. Although no satisfactory explanation is available yet the large neoclassical diffusion caused by the complex ripple structure of TJ-II magnetic field may be an important ingredient
Effect of nonlinear energy transport on neoclassical tearing mode stability in tokamak plasmas
Fitzpatrick, Richard
2017-05-01
An investigation is made into the effect of the reduction in anomalous perpendicular electron heat transport inside the separatrix of a magnetic island chain associated with a neoclassical tearing mode in a tokamak plasma, due to the flattening of the electron temperature profile in this region, on the overall stability of the mode. The onset of the neoclassical tearing mode is governed by the ratio of the divergences of the parallel and perpendicular electron heat fluxes in the vicinity of the island chain. By increasing the degree of transport reduction, the onset of the mode, as the divergence ratio is gradually increased, can be made more and more abrupt. Eventually, when the degree of transport reduction passes a certain critical value, the onset of the neoclassical tearing mode becomes discontinuous. In other words, when some critical value of the divergence ratio is reached, there is a sudden bifurcation to a branch of neoclassical tearing mode solutions. Moreover, once this bifurcation has been triggered, the divergence ratio must be reduced by a substantial factor to trigger the inverse bifurcation.
Neoclassical transport analysis for a class of high-β tokamak equilibria
International Nuclear Information System (INIS)
Rieser, H.; Werthmann, H.; Kuhn, S.
1995-01-01
Balescu's neoclassical transport theory is extended to the case of non-circular flux-surface geometries. Modified classical and neoclassical transport equations, governing particle and heat fluxes in the short- and long-mean-free-path regimes, are derived. These equations are shown to coincide to leading order with the corresponding equations given by Hirshman and Sigmar. They are then applied to an ideal MHD equilibrium, suitable as a simplified but analytically tractable model of a high-β tokamak. Numerical results for the radial profiles of the global (i.e. flux-surface integrated) particle and heat fluxes in the classical, Pfirsch-Schlueter and banana regimes are presented for geometry and plasma parameters realized in some tokamaks, like the divertor and injection tokamak experiment (DITE). This spatial representation provides direct insight into the overall collisional transport behaviour of a given equilibrium, whereas the anomalous transport problem is not addressed here. Our results demonstrate that for a given pressure profile the global neoclassical fluxes may depend very sensitively on the temperature profiles and that, in particular, the global classical and neoclassical ion heat fluxes exhibit a characteristic non-monotonic behaviour. (author)
Walker, Theodore, Jr.
2011-10-01
Anthropic reasoning about observation selection effects upon the appearance of cosmic providential fine-tuning (fine-tuning that provides for life) is often motivated by a desire to avoid theological implications (implications favoring the idea of a divine cosmic provider) without appealing to sheer lucky-for-us-cosmic-jackpot happenstance and coincidence. Cosmic coincidence can be rendered less incredible by appealing to a multiverse context. Cosmic providence can be rendered non-theological by appealing to an agent-less providential purpose, or by appealing to less-than-omnipresent/local providers, such as alien intelligences creating life- providing baby universes. Instead of choosing either cosmic coincidence or cosmic providence, as though they were mutually exclusive; it is better to accept both. Neoclassical thought accepts coincidence and providence, plus many local providers and one omnipresent provider. Moreover, fundamental observation selection theory should distinguish the many local observers of some events from the one omnipresent observer of all events. Accepting both coincidence and providence avoids classical theology (providence without coincidence) and classical atheism (coincidence without providence), but not neoclassical theology (providence with coincidence). Cosmology cannot avoid the idea of an all-inclusive omnipresent providential dice-throwing living-creative whole of reality, an idea essential to neoclassical theology, and to neoclassical cosmology.
Breton, S.; Casson, F. J.; Bourdelle, C.; Angioni, C.; Belli, E.; Camenen, Y.; Citrin, J.; Garbet, X.; Sarazin, Y.; Sertoli, M.; JET Contributors,
2018-01-01
Heavy impurities, such as tungsten (W), can exhibit strongly poloidally asymmetric density profiles in rotating or radio frequency heated plasmas. In the metallic environment of JET, the poloidal asymmetry of tungsten enhances its neoclassical transport up to an order of magnitude, so that
International Nuclear Information System (INIS)
Lazzaro, Enzo
2009-01-01
Established results of neoclassical kinetic theory are used in a fluid model to show that in low collisionality regimes (ν and 1/ν) the propagation velocity of Neoclassical Tearing Modes (NTM) magnetic islands of sufficient width is determined self-consistently by the Neoclassical Toroidal Viscosity (NTV) appearing because of broken symmetry. The NTV effect on bulk plasma rotation, may also explain recent observations on momentum transport. At the same time this affects the role of the neoclassical ion polarization current on neoclassical tearing modes (NTM) stability.
Moment approach to neoclassical flows, currents and transport in auxiliary heated tokamaks
International Nuclear Information System (INIS)
Kim, Yil Bong.
1988-02-01
The moment approach is utilized to derive the full complement of neoclassical transport processes in auxiliary heated tokamaks. The effects of auxiliary heating [neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH)] considered arise from the collisional interaction between the background plasma species and the fast-ion-tail species. From a known fast ion distribution function we evaluate the parallel (to the magnetic field) momentum and heat flow inputs to the background plasma. Then, through the momentum and heat flow balance equations, we can determine the induced parallel flows (and current) and radial transpot fluxes in ''equilibrium'' (on the time scale much longer than the collisional relaxation time, i.e., t >> 1ν/sub ii/). In addition to the fast-ion-induced current, the total neoclassical current includes the boostap current, which is driven by the pressure and temperature gradients, the Pfirsch-Schlueter current which is required for charge neutrality, and the neoclassical (including trapped particle effects) Spitzer current due to the parallel electric field. The radial transport fluxes also include off-diagonal compnents in the transport matrix which correspond to the Ware (neoclassical) pinch due to the inductive applied electric field an the fast-ion-induced radial fluxes, in addition to the usual pressure- and temperature-gradient-driven fluxes (particle diffusion and heat conduction). Once the tranport coefficient are completely determined, the radial fluxes and the heat fluxes can be substituted into the density and energy evolution equations to provide a complete description of ''equilibrium'' (δδt << ν/sub ii/) neoclassical transport processes in a plasma. 47 refs., 14 figs
International Nuclear Information System (INIS)
Murakami, Sadayoshi; Yamada, Hiroshi; Wakasa, Arimitsu
2002-01-01
Electron heat transport in low-collisionality LHD plasma is investigated in order to study the neoclassical transport optimization effect on thermal plasma transport with an optimization level typical of so-called ''advanced stellarators''. In the central region, a higher electron temperature is obtained in the optimized configuration, and transport analysis suggests the considerable effect of neoclassical transport on the electron heat transport assuming the ion-root level of radial electric field. The obtained experimental results support future reactor design in which the neoclassical and/or anomalous transports are reduced by magnetic field optimization in a non-axisymmetric configuration. (author)
International Nuclear Information System (INIS)
Sasao, Hajime; Watanabe, Kiyomasa; Inagaki, Shigeru
2000-01-01
The purpose of this paper is to show the change of the neoclassical transport and the radial electric field in the long pulse LHD plasmas by using the experimental ECE data. The neoclassical heat flux, which the neo-classical theory predicts, changes due to the change of the radial electric field. The increase of H ions injected by Neutral Beam Injection (NBI) in He discharge produce effect on the electric field. There is the threshold of H quantity on the change of the electric field polarity. (author)
The Qualitative Expectations Hypothesis
DEFF Research Database (Denmark)
Frydman, Roman; Johansen, Søren; Rahbek, Anders
2017-01-01
We introduce the Qualitative Expectations Hypothesis (QEH) as a new approach to modeling macroeconomic and financial outcomes. Building on John Muth's seminal insight underpinning the Rational Expectations Hypothesis (REH), QEH represents the market's forecasts to be consistent with the predictions...... of an economistís model. However, by assuming that outcomes lie within stochastic intervals, QEH, unlike REH, recognizes the ambiguity faced by an economist and market participants alike. Moreover, QEH leaves the model open to ambiguity by not specifying a mechanism determining specific values that outcomes take...
The Qualitative Expectations Hypothesis
DEFF Research Database (Denmark)
Frydman, Roman; Johansen, Søren; Rahbek, Anders
We introduce the Qualitative Expectations Hypothesis (QEH) as a new approach to modeling macroeconomic and financial outcomes. Building on John Muth's seminal insight underpinning the Rational Expectations Hypothesis (REH), QEH represents the market's forecasts to be consistent with the predictions...... of an economist's model. However, by assuming that outcomes lie within stochastic intervals, QEH, unlike REH, recognizes the ambiguity faced by an economist and market participants alike. Moreover, QEH leaves the model open to ambiguity by not specifying a mechanism determining specific values that outcomes take...
Gendreau, Keith; Cash, Webster; Gorenstein, Paul; Windt, David; Kaaret, Phil; Reynolds, Chris
2004-01-01
The Beyond Einstein Program in NASA's Office of Space Science Structure and Evolution of the Universe theme spells out the top level scientific requirements for a Black Hole Imager in its strategic plan. The MAXIM mission will provide better than one tenth of a microarcsecond imaging in the X-ray band in order to satisfy these requirements. We will overview the driving requirements to achieve these goals and ultimately resolve the event horizon of a supermassive black hole. We will present the current status of this effort that includes a study of a baseline design as well as two alternative approaches.
Social group utility maximization
Gong, Xiaowen; Yang, Lei; Zhang, Junshan
2014-01-01
This SpringerBrief explains how to leverage mobile users' social relationships to improve the interactions of mobile devices in mobile networks. It develops a social group utility maximization (SGUM) framework that captures diverse social ties of mobile users and diverse physical coupling of mobile devices. Key topics include random access control, power control, spectrum access, and location privacy.This brief also investigates SGUM-based power control game and random access control game, for which it establishes the socially-aware Nash equilibrium (SNE). It then examines the critical SGUM-b
Revisiting the Dutch hypothesis
Postma, Dirkje S.; Weiss, Scott T.; van den Berge, Maarten; Kerstjens, Huib A. M.; Koppelman, Gerard H.
The Dutch hypothesis was first articulated in 1961, when many novel and advanced scientific techniques were not available, such as genomics techniques for pinpointing genes, gene expression, lipid and protein profiles, and the microbiome. In addition, computed tomographic scans and advanced analysis
I.P. van Staveren (Irene)
2014-01-01
markdownabstract__Abstract__ This article explores the Lehman Sisters Hypothesis. It reviews empirical literature about gender differences in behavioral, experimental, and neuro-economics as well as in other fields of behavioral research. It discusses gender differences along three dimensions of
In a Trap of Neoclassical Economics and Marxism
Directory of Open Access Journals (Sweden)
Vladimir M. Yefimov
2017-03-01
Full Text Available This paper is a reaction to the book "Economic ideas and the world economic environment: a retrospective of interaction". The idea of writing a book with this title is just excellent. Traditional consideration of the development of economic ideas as exclusively intellectual history cannot give understanding of their evolution, since this evolution is influenced (often critically by a large number of external "factors". Why did I take the word "factors" in quotation marks? It is because this term is not very suitable to explain the evolution of economic ideas. It orients us to the causal model explaining this evolution, which for this purpose is totally inadequate. What kind of model, instead of causal, must be used here? In order to answer this question it is necessary to keep in mind that economic ideas are generated, developed and transmitted by people, immersed in certain social relations. These social relations are governed by certain rules, so in order to understand the evolution of economic ideas it is necessary to identify these rules. These rules are not confined to the desire of economists to understand economic reality. As it is shown by many historical studies of the real development of the economic discipline, the hypothesis, that social relations within the community of economists are motivated solely by the desire for a more accurate reflection of economic reality is fundamentally wrong. The author of the book is based on the hypothesis that "the theory is... more or less truthful reflection of contemporary to it conditions". The main, I would say fatal, mistake of the author of the book under consideration here is to use a causal model explaining the evolution of economic ideas, and selection of "technological factor" as a decisive factor acting in the framework of this model.
Energy Technology Data Exchange (ETDEWEB)
Andrews, Stephen A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sigeti, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-11-15
These are a set of slides about Bayesian hypothesis testing, where many hypotheses are tested. The conclusions are the following: The value of the Bayes factor obtained when using the median of the posterior marginal is almost the minimum value of the Bayes factor. The value of τ^{2} which minimizes the Bayes factor is a reasonable choice for this parameter. This allows a likelihood ratio to be computed with is the least favorable to H_{0}.
Christensen, Kim; Oomen, Roel; Renò, Roberto
2016-01-01
The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the...
International Nuclear Information System (INIS)
Shiina, S.; Yagi, Y.; Sugimoto, H.; Ashida, H.; Hirano, Y.; Koguchi, H.; Sakakita, H.; Taguchi, M.; Nagamine, Y.; Osanai, Y.; Saito, K.; Watanabe, M.; Aizawa, M.
2005-01-01
Dominant plasma self-induced current equilibrium is achieved together with the high β for the steady-state neoclassical reversed field pinch (RFP) equilibrium with low aspect ratio by broadening the plasma pressure profile. The RF-driven current, when the safety factor is smaller than unity, is much less than the self-induced current, which dominates (96%) the toroidal current. This neoclassical RFP equilibrium has strong magnetic shear or a high-stability beta (β t = 63%) due to its hollow current profile. It is shown that the obtained equilibrium is close to the relaxed-equilibrium state with a minimum energy, and is also robust against microinstabilities. These attractive features allow the economical design of compact steady-state fusion power plants with low cost of electricity (COE). (author)
International Nuclear Information System (INIS)
Rogister, A.L.
1999-01-01
'Subneoclassical' heat fluxes are predicted in the high collisionality regime by the revisited neoclassical theory, which includes the roles of Finite Larmor Radius effects and Inertia, that we published earlier. Unlike conventional neoclassical theory, the revisited theory further provides a non degenerate ambipolarity constraint which defines unambiguously the radial electric field. Together with the parallel momentum equation, the ambipolarity constraint leads, under some conditions, to radial electric field profiles with high negative shear akin to those observed in spontaneous edge transport barriers. The predictions of the theory are outlined, with emphasis laid on the interpretation of experimental results such as magnitude of the jumps, width of the shear layer, local scaling laws. Extension of the theory to triggered transitions and cold pulse propagation studies is suggested. (author)
Babin, Anatoli
2016-01-01
In this monograph, the authors present their recently developed theory of electromagnetic interactions. This neoclassical approach extends the classical electromagnetic theory down to atomic scales and allows the explanation of various non-classical phenomena in the same framework. While the classical Maxwell–Lorentz electromagnetism theory succeeds in describing the physical reality at macroscopic scales, it struggles at atomic scales. Here, quantum mechanics traditionally takes over to describe non-classical phenomena such as the hydrogen spectrum and de Broglie waves. By means of modifying the classical theory, the approach presented here is able to consistently explain quantum-mechanical effects, and while similar to quantum mechanics in some respects, this neoclassical theory also differs markedly from it. In particular, the newly developed framework omits probabilistic interpretations of the wave function and features a new fundamental spatial scale which, at the size of the free electron, is much lar...
Study of finite-orbit-width effect on neoclassical transport in tokamak core region
International Nuclear Information System (INIS)
Satake, Shinsuke; Okamoto, Masao
2004-01-01
Neoclassical transport simulation using the δf Monte-Carlo method is carried out to investigate the finite-orbit-width (FOW) effect on the transport near the magnetic axis. The time evolution of the radial electric field to maintain the ambipolarity of the flux is calculated simultaneously. It is found that, in the near-axis region, the ion heat flux decreases from the value predicted by the standard neoclassical theory both in the banana and plateau regimes. Though the radial transport shows a strong dependence on the FOW effect, the ambipolar electric field profile at the steady state is similar to that calculated in the small-orbit-width limit approximation. (author)
Energy Technology Data Exchange (ETDEWEB)
Pusztai, I. [Applied Physics, Chalmers University of Technology and Euratom-VR Association, SE-41296 Goeteborg (Sweden); Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Landreman, M. [University of Maryland, College Park, MD 20742 (United States); Mollen, A.; Fueloep, T. [Applied Physics, Chalmers University of Technology and Euratom-VR Association, SE-41296 Goeteborg (Sweden); Kazakov, Ye.O. [Laboratory for Plasma Physics, ERM/KMS, Association ' EURATOM-Belgian State' , TEC Partner, BE-1000 Brussels (Belgium)
2014-06-15
Poloidal asymmetries in the impurity density can be generated by radio frequency heating in the core and by neoclassical effects in the edge of tokamak plasmas. In a pedestal case study, using global neoclassical simulations we find that finite orbit width effects can generate significant poloidal variation in the electrostatic potential, which varies on a small radial scale. Gyrokinetic modeling shows that these poloidal asymmetries can be strong enough to significantly modify turbulent impurity peaking. In the pedestal the E x B drift in the radial electric field can give a larger contribution to the poloidal motion of impurities than that of their parallel streaming. Under such circumstances we find that up-down asymmetries can also affect impurity peaking. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Effect of Neoclassical Transport Optimization on Energetic Ion Confinement in LHD
International Nuclear Information System (INIS)
Murakami, S.; Yamada, H.; Sasao, M.
2004-01-01
Confinement of energetic ions from neutral beam injection heating is investigated by changing the magnetic field configuration of the Large Helical Device from a classical heliotron configuration to an optimized neoclassical transport configuration to a level typical of ''advanced stellarators.'' The experimental results show the highest count rate of fast neutral particles not in the optimized configuration but in the inward-shifted one. The GNET simulation results show a relatively good agreement with the experimental results, and they also show a lower energy loss rate in the optimized configuration. This contradiction can be explained by the radial profile of the energetic ions. The relatively good agreement between experimental and simulation results suggest that ripple transport (neoclassical) dominates the energetic ion confinement and that the optimization process is effective in improving confinement in helical systems
The effect on stellarator neoclassical transport of a fluctuating electrostatic spectrum
International Nuclear Information System (INIS)
Mynick, H.E.; Boozer, A.H.
2005-01-01
A study is presented of the effect on neoclassical transport of a fluctuating electrostatic spectrum, such as produced either by plasma turbulence, or imposed externally. For tokamaks, it is usually assumed that the neoclassical and 'anomalous' contributions to the transport roughly superpose, D=D nc +D an , an intuition also used in modeling stellarators. An alternate intuition, however, is one where it is the collisional and anomalous scattering frequencies which superpose, ν ef =ν+ν an . For nonaxisymmetric systems, in regimes where ∂D/∂ν ef picture' implies that turning on the fluctuations can decrease the total radial transport. Using numerical and analytic means, it is found that the total transport has contributions conforming to each of these intuitions, either of which can dominate. In particular, for stellarators, the ν ef picture is often valid, producing transport behavior differing from tokamaks
Neoclassical viscosities in NCSX and QPS with few toroidal periods and low aspect ratios
International Nuclear Information System (INIS)
Nishimura, S.; Mikkelsen, D.R.; Ku, L.P.; Mynick, H.E.; Zarnstorff, M.C.; Spong, D.A.; Hirshman, S.P.
2008-01-01
Previously reported benchmarking examples for the analytical formulas of neoclassical viscosities were made implicitly assuming applications in a future integrated simulation system for the LHD (Large Helical Device). Therefore the toroidal period numbers assumed there were mainly N=10. In this kind of calculation, however, an implicit (or sometimes explicit) assumption of ι/N<<1 is sometimes included. This assumption is included not only in simplified bounce averaged drift kinetic equations for ripple diffusions, but also in the equation before the averaging for non-bounce-averaged effects determining neoclassical parallel viscosity and the banana-plateau diffusions. To clarify the applicability of the analytical methods even for configurations with extremely low toroidal period numbers (required for low aspect ratios), we show here recent benchmarking examples in NCSX (National Compact Stellarator Experiment) with N=3 and QPS (Quasi-poloidal Stellarator) with N=2. (author)
Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks
International Nuclear Information System (INIS)
Qin, Hong; Guan, Xiaoyin; Fisch, Nathaniel J.
2011-01-01
In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ((var e psilon) -1 ) larger than the E x B velocity, where (var e psilon) is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.
International Nuclear Information System (INIS)
Lazzaro, E.; Comisso, L.; Valdettaro, L.
2010-01-01
In tokamaks magnetic islands arise from an unstable process of tearing and reconnecting of helical field lines across rational surfaces. After a linear stage the magnetic instability develops through three characteristic nonlinear stages where increasingly complex topological alterations occur in the form of the magnetic islands. The problem of response of reconnection process to the injection of an external current suitably localized is addressed using a four-field model in a plane slab plasma, with a novel extension to account consistently of the relevant neoclassical effects, such as bootstrap current and pressure anisotropy. The results found have implications on the interpretation of the possible mechanism of present day experimental results on neoclassical tearing modes as well as on the concepts for their control or avoidance.
Directory of Open Access Journals (Sweden)
Robert M. Solow
2012-10-01
Full Text Available The paper surveys the neoclassical theory of growth. As a preliminary, the meaning of the adjective "neoclassical" is discussed. The basic model is then sketched, and the conditions ensuring a stationary state are illustrated. The issue of the convergence to a stationary state (and that of the speed of convergence is further considered. A discussion of "primary factors" opens the way to the "new" theory of growth, with endogenous technical progress. A number of extensions of the basic model are then recalled: two-sector and multi-sectoral models, overlapping generations models, the role of money in growth models. JEL Codes: O41, E25Keywords: Distribution, Growth, Income Distribution, Income
Energy Technology Data Exchange (ETDEWEB)
Minami, T [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Fujisawa, A [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Iguchi, H [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Nishimura, S [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Ida, K [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Yokoyama, M [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Murakami, S [Department of Nuclear Engineering, Kyoto University, Kyoto (Japan); Yoshimura, Y [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Isobe, M [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Suzuki, C [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Nagaoka, K [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Akiyama, T [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Yoshinuma, M [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Shimizu, A [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Takahashi, C [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Matsuoka, K [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Okamura, S [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)
2004-05-01
Optimization has been carried out on the operational regime where neoclassical internal transport barriers (N-ITBs) are formed. The condition of the forming N-ITB is sensitive to the location of the electron cyclotron heating resonance zone. A high electron temperature is obtained for the central heating (-2 cm < R{sub resonance} < 2 cm). The variation of the magnetic axis location affects the formation of the N-ITB. The electron and ion temperatures at the magnetic axis location (R{sub ax}) of 94.9 cm are higher than those at 92.1 and 97.4 cm. This result indicates that the neoclassical flux and the created radial electric field are influenced by the magnetic field structure.
The dynamics of a neoclassical tearing mode (NTM) influenced by energetic ions on EAST
International Nuclear Information System (INIS)
Li, Erzhong; Xu, L; Shi, T; Zhao, H; Liu, Y; Ti, A; Zhang, J; Huang, J; Shen, B; Lin, S; Qian, J; Gong, X; Hu, L; Igochine, V; White, R; Zhu, Y
2016-01-01
In the 2014 year’s campaign of experimental advanced superconducting tokamak (EAST), a series of Magnetohydrodynamics (MHD) instabilities were observed as the launching of Neutral Beam Injection (NBI), the most interesting one of which is the neoclassical tearing mode (NTM). Evidence clearly shows that a kink mode present after a strong sawtooth-like (ST-like) crash leaves a perturbation near the location of the magnetic island, providing the initial seed. The interaction of energetic ions makes the magnetic island oscillate both in island width and in rotation frequency. Analysis indicates that the bulk plasma still dominates the dynamics of NTM, and the orbit excursion of energetic ions induces a polarization current and modifies the width and rotation frequency of the neoclassical magnetic island. (paper)
Directory of Open Access Journals (Sweden)
Eudaldo Enrique Espinoza Freire
2018-01-01
Full Text Available It is intended with this work to have a material with the fundamental contents, which enable the university professor to formulate the hypothesis, for the development of an investigation, taking into account the problem to be solved. For its elaboration, the search of information in primary documents was carried out, such as thesis of degree and reports of research results, selected on the basis of its relevance with the analyzed subject, current and reliability, secondary documents, as scientific articles published in journals of recognized prestige, the selection was made with the same terms as in the previous documents. It presents a conceptualization of the updated hypothesis, its characterization and an analysis of the structure of the hypothesis in which the determination of the variables is deepened. The involvement of the university professor in the teaching-research process currently faces some difficulties, which are manifested, among other aspects, in an unstable balance between teaching and research, which leads to a separation between them.
White, Mark D.
2017-01-01
Behavioral economics has enriched our understanding of the limitations and imperfections of human decision-making that were neglected by the overly simplistic neoclassical model of choice. However insightful its results and clever its modifications to the traditional model of choice, much of behavioral economics is built upon the core of that model, constrained preference-satisfaction, which cannot accommodate many other aspects of human choice such as principles, ideals, judgment, and will. ...
Neoclassical alpha-particle losses in tokamaks allowing for large orbit widths
International Nuclear Information System (INIS)
Cox, M.; O'Brien, M.R.; Zaitsev, F.S.
1994-01-01
Alpha-particle physics is of particular importance now that research into controlled fusion has reached thermonuclear parameters and D-T fuel has been used in JET and TFTR. Here we address the important topic of α-particle transport: if transport is too low helium ash accumulates quenching the burn; if it is too high heating of the plasma by fast α-particles is insufficient to maintain the burn. We give results from simulations of α-particle distributions (f α ) which self-consistently treat α-particle birth, collisional slowing down and neoclassical radial transport. The (steady-state) f α is calculated by the FPP code as a function of speed (v), pitch-angle (θ) and flux surface radius (r). This code is based on a 3D Fokker-Planck theory of 'banana regime' neoclassical effects in tokamaks which can treat large deviations of fast ion orbits from flux surfaces and non-Maxwellian distributions. The code reproduces standard neoclassical results for Maxwellian distributions in the large aspect ratio (ε) and small orbit width (Δ) limits (e.g. radial fluxes, conductivities and bootstrap currents), but can also be used for small ε and large Δ which are difficult to treat analytically. The code is particularly useful for α-particle studies as (a) the experimental evidence is that fast ion transport is usually consistent with neoclassical theory, unlike electron or thermal ion transport, and (b) trapped fast ion orbits can deviate greatly from flux surfaces. An alternative to this Fokker-Planck treatment is Monte Carlo modelling. However, representation of the detailed structure of f α (θ,v,r) would require very large number of particles, and hence be very slow. Calculations have been made for parameters typical of TFTR, JET, SSTR (an 'advanced tokamak' reactor) and STR (a tight aspect ratio or 'spherical' tokamak reactor, though only the JET results are discussed in detail. (author) 4 refs., 4 figs
Observation of neoclassical transport in reverse shear plasmas on the tokamak fusion test reactor
International Nuclear Information System (INIS)
Efthimion, P.C.; Goeler, S. von; Houlberg, W.A.
2001-01-01
Perturbative experiments on the Tokamak Fusion Test Reactor (TFTR) have investigated the transport of multiple ion species in reverse shear plasmas. The profile evolution of trace tritium and helium, and intrinsic carbon indicate the formation of core particle transport barriers in ERS plasmas. There is an order of magnitude reduction in the particle diffusivity inside the reverse shear region. The diffusivities for these species in ERS plasmas agree with neoclassical theory. (author)
Observation of neoclassical transport in reverse shear plasmas on the tokamak fusion test reactor
International Nuclear Information System (INIS)
Efthimion, P.C.; Von Goeler, S.; Houlberg, W.A.
1999-01-01
Perturbative experiments on the Tokamak Fusion Test Reactor (TFTR) have investigated the transport of multiple ion species in reverse shear plasmas. The profile evolution of trace tritium and helium, and intrinsic carbon indicate the formation of core particle transport barriers in ERS plasmas. There is an order of magnitude reduction in the particle diffusivity inside the reverse shear region. The diffusivities for these species in ERS plasmas agree with neoclassical theory. (author)
Observation of plasma toroidal-momentum dissipation by neoclassical toroidal viscosity.
Zhu, W; Sabbagh, S A; Bell, R E; Bialek, J M; Bell, M G; LeBlanc, B P; Kaye, S M; Levinton, F M; Menard, J E; Shaing, K C; Sontag, A C; Yuh, H
2006-06-09
Dissipation of plasma toroidal angular momentum is observed in the National Spherical Torus Experiment due to applied nonaxisymmetric magnetic fields and their plasma-induced increase by resonant field amplification and resistive wall mode destabilization. The measured decrease of the plasma toroidal angular momentum profile is compared to calculations of nonresonant drag torque based on the theory of neoclassical toroidal viscosity. Quantitative agreement between experiment and theory is found when the effect of toroidally trapped particles is included.
Development of a neoclassical transport database by neural network fitting in LHD
International Nuclear Information System (INIS)
Wakasa, Arimitsu; Oikawa, Shun-ichi; Murakami, Sadayoshi; Yamada, Hiroshi; Yokoyama, Masayuki; Watanabe, Kiyomasa; Maassberg, Hening; Beidler, Craig D.
2004-01-01
A database of neoclassical transport coefficients for the Large Helical Device is developed using normalized mono-energetic diffusion coefficients evaluated by Monte Carlo simulation code; DCOM. A neural network fitting method is applied to take energy convolutions with the given distribution function, e.g. Maxwellian. The database gives the diffusion coefficients as a function of the collision frequency, the radial electric field and the minor radius position. (author)
International Nuclear Information System (INIS)
Spanjer, Aldo R.
2009-01-01
Shifts at the international gas market indicate that the transaction cost perspective provides better underpinnings for European gas regulation than the current neoclassical perspective. Three implications are that policymakers should: (1) allow alternative coordination measures to complement market exchange; (2) recognize that less than perfect competition outcomes may be optimal and (3) be more reticent in prescribing interventionist measures. Finally, the analysis provides the foundations for the empirical research required to complement this paper's theoretical approach. (author)
Extension and comparison of neoclassical models for poloidal rotation in tokamaks
International Nuclear Information System (INIS)
Stacey, W. M.
2008-01-01
Several neoclassical models for the calculation of poloidal rotation in tokamaks were rederived within a common framework, extended to include additional physics and numerically compared. The importance of new physics phenomena not usually included in poloidal rotation calculations (e.g., poloidal electric field, VxB force resulting from enhanced radial particle flow arising from the ionization of recycling neutrals) was examined. Extensions of the Hirshman-Sigmar, Kim-Diamond-Groebner, and Stacey-Sigmar poloidal rotation models are presented
Benchmark of the local drift-kinetic models for neoclassical transport simulation in helical plasmas
Huang, B.; Satake, S.; Kanno, R.; Sugama, H.; Matsuoka, S.
2017-02-01
The benchmarks of the neoclassical transport codes based on the several local drift-kinetic models are reported here. Here, the drift-kinetic models are zero orbit width (ZOW), zero magnetic drift, DKES-like, and global, as classified in Matsuoka et al. [Phys. Plasmas 22, 072511 (2015)]. The magnetic geometries of Helically Symmetric Experiment, Large Helical Device (LHD), and Wendelstein 7-X are employed in the benchmarks. It is found that the assumption of E ×B incompressibility causes discrepancy of neoclassical radial flux and parallel flow among the models when E ×B is sufficiently large compared to the magnetic drift velocities. For example, Mp≤0.4 where Mp is the poloidal Mach number. On the other hand, when E ×B and the magnetic drift velocities are comparable, the tangential magnetic drift, which is included in both the global and ZOW models, fills the role of suppressing unphysical peaking of neoclassical radial-fluxes found in the other local models at Er≃0 . In low collisionality plasmas, in particular, the tangential drift effect works well to suppress such unphysical behavior of the radial transport caused in the simulations. It is demonstrated that the ZOW model has the advantage of mitigating the unphysical behavior in the several magnetic geometries, and that it also implements the evaluation of bootstrap current in LHD with the low computation cost compared to the global model.
Energy Technology Data Exchange (ETDEWEB)
Nishioka, K.; Nakamura, Y. [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Nishimura, S. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Lee, H. Y. [Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kobayashi, S.; Mizuuchi, T.; Nagasaki, K.; Okada, H.; Minami, T.; Kado, S.; Yamamoto, S.; Ohshima, S.; Konoshima, S.; Sano, F. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)
2016-03-15
A moment approach to calculate neoclassical transport in non-axisymmetric torus plasmas composed of multiple ion species is extended to include the external parallel momentum sources due to unbalanced tangential neutral beam injections (NBIs). The momentum sources that are included in the parallel momentum balance are calculated from the collision operators of background particles with fast ions. This method is applied for the clarification of the physical mechanism of the neoclassical parallel ion flows and the multi-ion species effect on them in Heliotron J NBI plasmas. It is found that parallel ion flow can be determined by the balance between the parallel viscosity and the external momentum source in the region where the external source is much larger than the thermodynamic force driven source in the collisional plasmas. This is because the friction between C{sup 6+} and D{sup +} prevents a large difference between C{sup 6+} and D{sup +} flow velocities in such plasmas. The C{sup 6+} flow velocities, which are measured by the charge exchange recombination spectroscopy system, are numerically evaluated with this method. It is shown that the experimentally measured C{sup 6+} impurity flow velocities do not contradict clearly with the neoclassical estimations, and the dependence of parallel flow velocities on the magnetic field ripples is consistent in both results.
Neoclassical and anomalous transport in axisymmetric toroidal plasmas with electrostatic turbulence
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1995-01-01
Neoclassical and anomalous transport fluxes are determined for axisymmetric toroidal plasmas with weak electrostatic fluctuations. The neoclassical and anomalous fluxes are defined based on the ensemble-averaged kinetic equation with the statistically averaged nonlinear term. The anomalous forces derived from that quasilinear term induce the anomalous particle and heat fluxes. The neoclassical banana-plateau particle and heat fluxes and the bootstrap current are also affected by the fluctuations through the parallel anomalous forces and the modified parallel viscosities. The quasilinear term, the anomalous forces, and the anomalous particle and heat fluxes are evaluated from the fluctuating part of the drift kinetic equation. The averaged drift kinetic equation with the quasilinear term is solved for the plateau regime to derive the parallel viscosities modified by the fluctuations. The entropy production rate due to the anomalous transport processes is formulated and used to identify conjugate pairs of the anomalous fluxes and forces, which are connected by the matrix with the Onsager symmetry. copyright 1995 American Institute of Physics
Analysis of radial electric field bifurcation in LHD based on neoclassical transport theory
International Nuclear Information System (INIS)
Yokoyama, Masayuki; Ida, Katsumi; Shimozuma, Takashi
2003-01-01
Radial electric field (E r ) properties in LHD have been investigated based on the neoclassical transport theory and have also applied to LHD experimental results. The effects of the helicity of the magnetic configuration on the condition required to realize the electron root are examined. The larger helicity makes the threshold temperature lower for the same electron density. A higher threshold temperature is anticipated to be required in the plasma core region based on this fact and also due to the larger density there. This high electron temperature (T e ) has been successfully obtained with a center-focused ECH. There is a threshold for the ECH power to achieve a steep gradient of T e , and it seems to be qualitatively consistent with the transition of E r , at least in the sense that the abrupt increase of T e occurs after entering the anticipated electron root regime. These experimental results, consistent with those of analysis of the neoclassical ambipolar E r , indicate that the transition phenomena of E r in LHD are predominantly governed by neoclassical features. (author)
Neoclassical Diffusion of Radiation-Belt Electrons Across Very Low L-Shells
Cunningham, Gregory S.; Loridan, Vivien; Ripoll, Jean-François; Schulz, Michael
2018-04-01
In the presence of drift-shell splitting intrinsic to the International Geomagnetic Reference Field magnetic field model, pitch angle scattering from Coulomb collisions experienced by radiation-belt electrons in the upper atmosphere and ionosphere produces extra radial diffusion, a form of neoclassical diffusion. The strength of the neoclassical radial diffusion at L nuclear detonation. The data show apparent lifetimes 10-100 times as long as would have been expected from collisional pitch angle diffusion and Coulomb drag alone. Our model reproduces apparent lifetimes for >0.5-MeV electrons in the region 1.14 < L < 1.26 to within a factor of 2 (comparable to the uncertainty quoted for the observations). We conclude that neoclassical radial diffusion (resulting from drift-shell splitting intrinsic to International Geomagnetic Reference Field's azimuthal asymmetries) mitigates the decay expected from collisional pitch angle diffusion and inelastic energy loss alone and thus contributes importantly to the long apparent lifetimes observed at these low L-shells.
International Nuclear Information System (INIS)
Bell, R.E.; Andre, R.; Kaye, S.M.; Kolesnikov, R.A.; LeBlance, B.P.; Rewolldt, G.; Wang, W.X.; Sabbagh, S.A.
2010-01-01
Knowledge of poloidal velocity is necessary for the determination of the radial electric field, Er, which along with its gradient is linked to turbulence suppression and transport barrier formation. Recent measurements of poloidal flow on conventional tokamaks have been reported to be an order of magnitude larger than expected from neoclassical theory. In contrast, recent poloidal velocity measurements on the NSTX spherical torus (S. M. Kaye et al., Phys. Plasmas 8, 1977 (2001)) are near or below neoclassical estimates. A novel charge exchange recombination spectroscopy diagnostic is used, which features active and passive sets of up/down symmetric views to produce line-integrated poloidal velocity measurements that do not need atomic physics corrections. Local profiles are obtained with an inversion. Poloidal velocity measurements are compared with neoclassical values computed with the codes NCLASS (W. A. Houlberg et al., Phys. Plasmas 4, 3230 (1997)) and GTC-Neo (W. X. Wang, et al., Phys. Plasmas 13, 082501 (2006)), which has been updated to handle impurities.
Study of neoclassical transport in the 1/ν regime for a research fusion reactor
International Nuclear Information System (INIS)
Kalyuzhnyj, V.N.; Kasilov, S.V.; Nemov, V.V.
2005-01-01
In frame of the concept of a steady-state operated research fusion reactor (RFR) in papers [1-4] the RFR with an increased plasma-wall detachment was proposed with the purpose to enable not only the production but also a long-term confinement of a self-sustained plasma at the existing technology level. In connection with complication of the corresponding magnetic configuration an investigation of the neoclassical transport is desirable for such systems. In the present work neoclassical transport for a magnetic configuration of l=2 torsatron type variant of RFR system with an additional opposite toroidal magnetic field is investigated numerically. A so-called 1/ν transport regime, in which the transport coefficients are increased with reduction of particle collision frequency ν is considered. For calculating of transport coefficients a technique, based on integration along magnetic field lines in a given stellarator magnetic field is used. The magnetic field of helical windings is calculated by Biot-Savart law. The obtained transport coefficients are presented in a standard form containing a factor depending on the magnetic field geometry. From analysis of the received results follows that in respect of the neoclassical transport the proposed magnetic configuration turns out to be closer to configuration of the classical stellarator (with helical winding), than to configuration of the classical torsatron/geliotron. (author)
Maximal Bell's inequality violation for non-maximal entanglement
International Nuclear Information System (INIS)
Kobayashi, M.; Khanna, F.; Mann, A.; Revzen, M.; Santana, A.
2004-01-01
Bell's inequality violation (BIQV) for correlations of polarization is studied for a product state of two two-mode squeezed vacuum (TMSV) states. The violation allowed is shown to attain its maximal limit for all values of the squeezing parameter, ζ. We show via an explicit example that a state whose entanglement is not maximal allow maximal BIQV. The Wigner function of the state is non-negative and the average value of either polarization is nil
[Dilemma of null hypothesis in ecological hypothesis's experiment test.
Li, Ji
2016-06-01
Experimental test is one of the major test methods of ecological hypothesis, though there are many arguments due to null hypothesis. Quinn and Dunham (1983) analyzed the hypothesis deduction model from Platt (1964) and thus stated that there is no null hypothesis in ecology that can be strictly tested by experiments. Fisher's falsificationism and Neyman-Pearson (N-P)'s non-decisivity inhibit statistical null hypothesis from being strictly tested. Moreover, since the null hypothesis H 0 (α=1, β=0) and alternative hypothesis H 1 '(α'=1, β'=0) in ecological progresses are diffe-rent from classic physics, the ecological null hypothesis can neither be strictly tested experimentally. These dilemmas of null hypothesis could be relieved via the reduction of P value, careful selection of null hypothesis, non-centralization of non-null hypothesis, and two-tailed test. However, the statistical null hypothesis significance testing (NHST) should not to be equivalent to the causality logistical test in ecological hypothesis. Hence, the findings and conclusions about methodological studies and experimental tests based on NHST are not always logically reliable.
Maximally Symmetric Composite Higgs Models.
Csáki, Csaba; Ma, Teng; Shu, Jing
2017-09-29
Maximal symmetry is a novel tool for composite pseudo Goldstone boson Higgs models: it is a remnant of an enhanced global symmetry of the composite fermion sector involving a twisting with the Higgs field. Maximal symmetry has far-reaching consequences: it ensures that the Higgs potential is finite and fully calculable, and also minimizes the tuning. We present a detailed analysis of the maximally symmetric SO(5)/SO(4) model and comment on its observational consequences.
Principles of maximally classical and maximally realistic quantum ...
Indian Academy of Sciences (India)
Principles of maximally classical and maximally realistic quantum mechanics. S M ROY. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India. Abstract. Recently Auberson, Mahoux, Roy and Singh have proved a long standing conjecture of Roy and Singh: In 2N-dimensional phase space, ...
Energy Technology Data Exchange (ETDEWEB)
Yamoto, S.; Inoue, H.; Sawada, Y.; Hatayama, A. [Faculty of Science and Technology, Keio University, Yokohama (Japan); Homma, Y.; Hoshino, K. [Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Bonnin, X. [ITER Organization, St. Paul Lez Durance (France); Coster, D. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Schneider, R. [Ernst-Moritz-Arndt University Greifswald (Germany)
2016-08-15
The initial simulation study of the neoclassical perpendicular self-diffusion transport in the SOL/Divertor regions for a realistic tokamak geometry with the IMPGYRO code has been performed in this paper. One of the most unique features of the IMPGYRO code is calculating exact Larmor orbit of the test particle instead of assuming guiding center approximation. Therefore, effects of the magnetic drifts in realistic tokamaks are naturally taken into account in the IMPGYRO code. This feature makes it possible to calculate neoclassical transport processes, which possibly become large in the SOL/divertor plasma. Indeed, neoclassical self-diffusion process, the resultant effect of the combination of magnetic drift and Coulomb collisions with background ions, has already been included in the IMPGYRO model. In the present paper, prior to implementing the detailed model of neoclassical transport process into IMPGYRO, we have investigated the effect of neoclassical selfdiffusion in a realistic tokamak geometry with lower single null X-point. We also use a model with guiding center approximation in order to compare with the IMPGYRO full orbit model. The preliminary calculation results of each model have shown differences in the perpendicular average velocity of impurity ions at the top region of the SOL. The mechanism which leads to the difference has been discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
The Bergschrund Hypothesis Revisited
Sanders, J. W.; Cuffey, K. M.; MacGregor, K. R.
2009-12-01
After Willard Johnson descended into the Lyell Glacier bergschrund nearly 140 years ago, he proposed that the presence of the bergschrund modulated daily air temperature fluctuations and enhanced freeze-thaw processes. He posited that glaciers, through their ability to birth bergschrunds, are thus able to induce rapid cirque headwall retreat. In subsequent years, many researchers challenged the bergschrund hypothesis on grounds that freeze-thaw events did not occur at depth in bergschrunds. We propose a modified version of Johnson’s original hypothesis: that bergschrunds maintain subfreezing temperatures at values that encourage rock fracture via ice lensing because they act as a cold air trap in areas that would otherwise be held near zero by temperate glacial ice. In support of this claim we investigated three sections of the bergschrund at the West Washmawapta Glacier, British Columbia, Canada, which sits in an east-facing cirque. During our bergschrund reconnaissance we installed temperature sensors at multiple elevations, light sensors at depth in 2 of the 3 locations and painted two 1 m2 sections of the headwall. We first emphasize bergschrunds are not wanting for ice: verglas covers significant fractions of the headwall and icicles dangle from the base of bödens or overhanging rocks. If temperature, rather than water availability, is the limiting factor governing ice-lensing rates, our temperature records demonstrate that the bergschrund provides a suitable environment for considerable rock fracture. At the three sites (north, west, and south walls), the average temperature at depth from 9/3/2006 to 8/6/2007 was -3.6, -3.6, and -2.0 °C, respectively. During spring, when we observed vast amounts of snow melt trickle in to the bergschrund, temperatures averaged -3.7, -3.8, and -2.2 °C, respectively. Winter temperatures are even lower: -8.5, -7.3, and -2.4 °C, respectively. Values during the following year were similar. During the fall, diurnal
The principle of holism in post-neoclassical philosophy of history
Directory of Open Access Journals (Sweden)
Y. A. Dobrolyubska
2014-02-01
Full Text Available The principle of holism restores historical science tendency to grasp the past as a «whole matter» and raises the questions about the global synthesis, based on the integration of micro and makrohistory, narrative and metatheory. Postneoclassical subsystem in the philosophy of history operates of the corresponding concept of truth. Scientific truth is always contextual. She stated subject to the methodological postulates, which designed a specific research situation. Historical studies of scientific search for truth is always associated with the study of specific historical events or historical building theories. Both approaches solve the problem of objectivity: a theoretical history try to discover the truth, liberated from specific features and history of events wishes to discover the truth, given in the particular nuances of the entire event. Based on the corresponding concept of truth postneoclassical subsystem aims to reconstruct the historical reality in all its fullness, complexity and specificity. This subsystem comes to the fundamental principle of postneoclassical philosophy of history – to the principle of holism. On the one hand this principle orients the historian to the need for a holistic study of the subject of research, on the other hand he directs the historian to the study of historical reality as a hierarchy of «integrality», which can not be reduced to the parts that make up. Also it is emphasized that the meaning of these parts must necessarily be present as a sense of the whole context.
Neoclassical transport in a multiple-helicity torsatron in the low-collisionality (1/#betta#) regime
International Nuclear Information System (INIS)
Shaing, K.C.; Hokin, S.A.
1983-02-01
For a sufficiently high number of field periods (m/iota > l), the magnetic field of a multiple helicity torsatron can be reduced to a simple form such that the second adiabatic invariant J can be calculated. It is found that the particle and the heat fluxes for a multiple helicity torsatron in the low collisionality (1/#betta#) regime have the same geometric dependences. An optimization of both quantities is carried out for a given equilibrium constraint. It is shown that the transport fluxes can be smaller than those of the conventional stellarator by an order of magnitude. The effect of finite plasma beta on the neoclassical fluxes is also studied
A model for the neoclassical toroidal viscosity effect on Edge plasma toroidal rotation
Energy Technology Data Exchange (ETDEWEB)
Miron, I.G. [National Institute for Laser, Plasma and Radiation Physics, Euratom-MEdC Association, Bucharest (Romania)
2013-11-15
A semianalytic expression for the edge plasma angular toroidal rotation frequency that includes the neoclassical toroidal viscosity braking influence is obtained. Based on the model presented in a previous paper [I.G. Miron, Contrib. Plasma Phys. 53, 214 (2013)], the less destabilizing error field spectrum is found in order to minimize the nonlinear effect of the NTV on the toroidal rotation of the edge of the plasma. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Validation of neoclassical bootstrap current models in the edge of an H-mode plasma.
Wade, M R; Murakami, M; Politzer, P A
2004-06-11
Analysis of the parallel electric field E(parallel) evolution following an L-H transition in the DIII-D tokamak indicates the generation of a large negative pulse near the edge which propagates inward, indicative of the generation of a noninductive edge current. Modeling indicates that the observed E(parallel) evolution is consistent with a narrow current density peak generated in the plasma edge. Very good quantitative agreement is found between the measured E(parallel) evolution and that expected from neoclassical theory predictions of the bootstrap current.
Neoclassical theory of elementary charges with spin of 1/2
Energy Technology Data Exchange (ETDEWEB)
Babin, Anatoli; Figotin, Alexander [Department of Mathematics University of California at Irvine, Irvine, California 92697-3875 (United States)
2014-08-15
We advance here our neoclassical theory of elementary charges by integrating into it the concept of spin of 1/2. The developed spinorial version of our theory has many important features identical to those of the Dirac theory such as the gyromagnetic ratio, expressions for currents including the spin current, and antimatter states. In our theory, the concepts of charge and anticharge relate naturally to their “spin” in its rest frame in two opposite directions. An important difference with the Dirac theory is that both the charge and anticharge energies are positive whereas their frequencies have opposite signs.
Nguyen, Thanh-Son; Selinger, Jonathan V
2017-09-01
In liquid crystal elastomers and polymer networks, the orientational order of liquid crystals is coupled with elastic distortions of crosslinked polymers. Previous theoretical research has described these materials through two different approaches: a neoclassical theory based on the liquid crystal director and the deformation gradient tensor, and a geometric elasticity theory based on the difference between the actual metric tensor and a reference metric. Here, we connect those two approaches using a formalism based on differential geometry. Through this connection, we determine how both the director and the geometry respond to a change of temperature.
Effect of neoclassical toroidal viscosity on error-field penetration thresholds in tokamak plasmas.
Cole, A J; Hegna, C C; Callen, J D
2007-08-10
A model for field-error penetration is developed that includes nonresonant as well as the usual resonant field-error effects. The nonresonant components cause a neoclassical toroidal viscous torque that keeps the plasma rotating at a rate comparable to the ion diamagnetic frequency. The new theory is used to examine resonant error-field penetration threshold scaling in Ohmic tokamak plasmas. Compared to previous theoretical results, we find the plasma is less susceptible to error-field penetration and locking, by a factor that depends on the nonresonant error-field amplitude.
International Nuclear Information System (INIS)
1983-01-01
During the 12-month period, October 1, 1982 to September 30, 1983 the Levitated Octupole has been dedicated to a study of neoclassical currents. At beta values of a few percent, both the Pfirsch-Schlueter current and the bootstrap current have been observed and compared with theoretical predictions. The spatial variation of the current both radially and poloidally are found to agree with the prediction over a wide range of collisionality. A four megawatt ICRH capability exists for sustaining the current in steady state
Directory of Open Access Journals (Sweden)
Marcos Antônio de Camargos
2005-12-01
Full Text Available The concept of creating wealth for stockholders through stock price increases usually accompanies a merger or acquisition. This ongoing appeal continues to be defended by those demonstrating such price increases and is contested by adversaries. Analyses were made of the market reaction and return of open companies on the Brazilian stock exchange, BOVESPA, after mergers and acquisitions between July 1994 and July 2002 based upon abnormal returns close to the press releases. The method used was the Event-Study and statistical treatment made use of the One-Way ANOVA and T test (One-Sample Test. Mergers and acquisitions analyzed had no statistically significant impact on the price of the stocks although there was a tendency for abnormal returns to recede after press releases, so that no real gains resulted, contrary to this hypothesis of wealth maximization.A lógica subjacente a um processo de fusão ou aquisição geralmente é a potencial criação de riqueza para os acionistas na forma de valorização acionária. Trata-se de um tema recorrente, ainda permeado por embates de estudiosos que defendem ou encontraram evidências empíricas de valorização das ações, contra os que a contestam. O artigo avaliou a reação do mercado e a rentabilidade de ações de companhias adquirentes de capital aberto brasileiras que passaram por processos de fusão ou aquisição no âmbito do mercado da BOVESPA, entre julho de 1994 e julho de 2002, por meio da análise de retornos anormais em períodos próximos a cada anúncio. A metodologia utilizada foi um Estudo de Evento. No tratamento estatístico foram utilizados os testes One-Way ANOVA e o Teste T para uma amostra (One-Sample Test. Concluiu-se que os processos de fusão ou aquisição estudados não causaram impactos significativos estatisticamente no preço das ações, apesar da tendência de queda da média dos retornos anormais após a divulgação do evento, e que esses processos não resultaram
Maximizing and customer loyalty: Are maximizers less loyal?
Directory of Open Access Journals (Sweden)
Linda Lai
2011-06-01
Full Text Available Despite their efforts to choose the best of all available solutions, maximizers seem to be more inclined than satisficers to regret their choices and to experience post-decisional dissonance. Maximizers may therefore be expected to change their decisions more frequently and hence exhibit lower customer loyalty to providers of products and services compared to satisficers. Findings from the study reported here (N = 1978 support this prediction. Maximizers reported significantly higher intentions to switch to another service provider (television provider than satisficers. Maximizers' intentions to switch appear to be intensified and mediated by higher proneness to regret, increased desire to discuss relevant choices with others, higher levels of perceived knowledge of alternatives, and higher ego involvement in the end product, compared to satisficers. Opportunities for future research are suggested.
Implications of maximal Jarlskog invariant and maximal CP violation
International Nuclear Information System (INIS)
Rodriguez-Jauregui, E.; Universidad Nacional Autonoma de Mexico
2001-04-01
We argue here why CP violating phase Φ in the quark mixing matrix is maximal, that is, Φ=90 . In the Standard Model CP violation is related to the Jarlskog invariant J, which can be obtained from non commuting Hermitian mass matrices. In this article we derive the conditions to have Hermitian mass matrices which give maximal Jarlskog invariant J and maximal CP violating phase Φ. We find that all squared moduli of the quark mixing elements have a singular point when the CP violation phase Φ takes the value Φ=90 . This special feature of the Jarlskog invariant J and the quark mixing matrix is a clear and precise indication that CP violating Phase Φ is maximal in order to let nature treat democratically all of the quark mixing matrix moduli. (orig.)
Phenomenology of maximal and near-maximal lepton mixing
International Nuclear Information System (INIS)
Gonzalez-Garcia, M. C.; Pena-Garay, Carlos; Nir, Yosef; Smirnov, Alexei Yu.
2001-01-01
The possible existence of maximal or near-maximal lepton mixing constitutes an intriguing challenge for fundamental theories of flavor. We study the phenomenological consequences of maximal and near-maximal mixing of the electron neutrino with other (x=tau and/or muon) neutrinos. We describe the deviations from maximal mixing in terms of a parameter ε(equivalent to)1-2sin 2 θ ex and quantify the present experimental status for |ε| e mixing comes from solar neutrino experiments. We find that the global analysis of solar neutrino data allows maximal mixing with confidence level better than 99% for 10 -8 eV 2 ∼ 2 ∼ -7 eV 2 . In the mass ranges Δm 2 ∼>1.5x10 -5 eV 2 and 4x10 -10 eV 2 ∼ 2 ∼ -7 eV 2 the full interval |ε| e mixing in atmospheric neutrinos, supernova neutrinos, and neutrinoless double beta decay
Maximal quantum Fisher information matrix
International Nuclear Information System (INIS)
Chen, Yu; Yuan, Haidong
2017-01-01
We study the existence of the maximal quantum Fisher information matrix in the multi-parameter quantum estimation, which bounds the ultimate precision limit. We show that when the maximal quantum Fisher information matrix exists, it can be directly obtained from the underlying dynamics. Examples are then provided to demonstrate the usefulness of the maximal quantum Fisher information matrix by deriving various trade-off relations in multi-parameter quantum estimation and obtaining the bounds for the scalings of the precision limit. (paper)
International Nuclear Information System (INIS)
Mikhailovskii, A.B.; Shirokov, M.S.; Konovalov, S.V.; Tsypin, V.S.
2005-01-01
Transport threshold models of neoclassical tearing modes in tokamaks are investigated analytically. An analysis is made of the competition between strong transverse heat transport, on the one hand, and longitudinal heat transport, longitudinal heat convection, longitudinal inertial transport, and rotational transport, on the other hand, which leads to the establishment of the perturbed temperature profile in magnetic islands. It is shown that, in all these cases, the temperature profile can be found analytically by using rigorous solutions to the heat conduction equation in the near and far regions of a chain of magnetic islands and then by matching these solutions. Analytic expressions for the temperature profile are used to calculate the contribution of the bootstrap current to the generalized Rutherford equation for the island width evolution with the aim of constructing particular transport threshold models of neoclassical tearing modes. Four transport threshold models, differing in the underlying competing mechanisms, are analyzed: collisional, convective, inertial, and rotational models. The collisional model constructed analytically is shown to coincide exactly with that calculated numerically; the reason is that the analytical temperature profile turns out to be the same as the numerical profile. The results obtained can be useful in developing the next generation of general threshold models. The first steps toward such models have already been made
Monte Carlo δf simulations of neoclassical phenomena in tokamak plasmas
International Nuclear Information System (INIS)
Bergmann, A.
2002-01-01
Some important neoclassical phenomena are studied with drift-kinetic simulations of the ions: the current which drives neoclassical tearing modes, the bootstrap current at a steep gradient, the energy transport near the axis. The δ f code HAGIS is used with pitch angle collisions modelled by a Monte Carlo procedure. An equilibrium with circular cross section and (for the island modelling) a single helical perturbation is considered, ITER- and AUG-like parameter are used. We find that the bootstrap current in small islands does not vanish, the full current is observed if the island half-width is smaller than the orbit width. The results can explain the scaling of the normalized beta at the onset of the NTMs in ASDEX Upgrade. The polarization current due to the island rotation is studied as well and found to be small. In the banana regime the bootstrap current at a steep pressure profile is reduced if the orbit width exceeds the gradient length. The near axis energy transport is neither reduced nor much enhanced in plateau regime, contrary to the banana regime. (author)
Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST
International Nuclear Information System (INIS)
Henderson, S.S.; O'Mullane, M.; Summers, H.P.; Garzotti, L.; Casson, F.J.; Dickinson, D.; Fox, M.F.J.; Patel, A.; Roach, C.M.; Valovič, M.
2014-01-01
Time-dependent helium gas puff experiments have been performed on the Mega Ampère Spherical Tokamak (MAST) during a two point plasma current scan in L-mode and a confinement scan at 900 kA. An evaluation of the He II (n = 4 → 3) spectrum line induced by charge exchange suggests anomalous rates of diffusion and inward convection in the outer regions of both L-mode plasmas. Similar rates of diffusion are found in the H-mode plasma, however these rates are consistent with neoclassical predictions. The anomalous inward pinch found in the core of L-mode plasmas is also not apparent in the H-mode core. Linear gyrokinetic simulations of one flux surface in L-mode using the GS2 and GKW codes find that equilibrium flow shear is sufficient to stabilize ITG modes, consistent with beam emission spectroscopy (BES) observations, and suggest that collisionless TEMs may dominate the anomalous helium particle transport. A quasilinear estimate of the dimensionless peaking factor associated with TEMs is in good agreement with experiment. Collisionless TEMs are more stable in H-mode because the electron density gradient is flatter. The steepness of this gradient is therefore pivotal in determining the inward neoclassical particle pinch and the particle flux associated with TEM turbulence. (paper)
International Nuclear Information System (INIS)
Bruma, C.; Cuperman, S.; Komoshvili, K.
1998-01-01
Several low aspect ratio (spherical) Tokamaks (ST's) are now in operation or under construction. These devices would permit cost-effective and attractive embodiment of future fusion reactors: they would provide high β, good confinement and steady state operation at modest field values. Now, a steady state reactor has to be sustained by non-inductively driven currents. Recently, the generation of non-inductive current drive by Alfven waves (AWCD) has been investigated theoretically within the framework of ideal (E p arallel=0) MHD and non-ideal, resistive (E p arallel≠0) MHD; however, in all these cases, the tokamak device consisted of a cylindrical plasma with simulated toroidal effects. Rather encouraging results have been obtained. In this work we further investigate AWCD in ST's as follows: (i) we use consistent equilibrium profiles with neoclassical conductivity corresponding to an ohmic START discharge; (ii) incorporate effects due to neoclassical conductivity in the elements of the resistive MHD dielectric tensor, in the solution of the full (E p arallel≠0) wave equation as well as in the calculation of AWCD; and (iii) carry out a systematic search for antenna parameters optimizing the AWCD. (author)
Energy Technology Data Exchange (ETDEWEB)
Bruma, C.; Cuperman, S.; Komoshvili, K. [School of Physics and Astronomy, Tel Aviv University, Tel Aviv (Israel)
1998-08-01
Several low aspect ratio (spherical) Tokamaks (ST's) are now in operation or under construction. These devices would permit cost-effective and attractive embodiment of future fusion reactors: they would provide high {beta}, good confinement and steady state operation at modest field values. Now, a steady state reactor has to be sustained by non-inductively driven currents. Recently, the generation of non-inductive current drive by Alfven waves (AWCD) has been investigated theoretically within the framework of ideal (E{sub p}arallel=0) MHD and non-ideal, resistive (E{sub p}arallel{ne}0) MHD; however, in all these cases, the tokamak device consisted of a cylindrical plasma with simulated toroidal effects. Rather encouraging results have been obtained. In this work we further investigate AWCD in ST's as follows: (i) we use consistent equilibrium profiles with neoclassical conductivity corresponding to an ohmic START discharge; (ii) incorporate effects due to neoclassical conductivity in the elements of the resistive MHD dielectric tensor, in the solution of the full (E{sub p}arallel{ne}0) wave equation as well as in the calculation of AWCD; and (iii) carry out a systematic search for antenna parameters optimizing the AWCD. (author)
International Nuclear Information System (INIS)
Dini, F.; Khorasani, S.
2007-01-01
Configuration of Tokamak plasma has a dominant effect on its parameters. In the calculation of transport, there are some transport coefficients and quantities, where the knowledge of their precise values, according to the system of equations, is essential to be realized. Tokamak has a toroidal configuration, in addition to classical effects, it is necessary to study the neoclassical effects due to the field curvature. The trapped particles in strong electromagnetic fields oscillate on banana-shaped orbits which in turn affect many other collisional transport parameters. Here, a precise estimation of trapped particles based on the standard equilibrium model for an elliptical shape of Tokamak plasma has been carried out using Lin-Liu model. It should be added that in this calculation, the profile of the averaged magnetic field on the flux surfaces has been derived using analytical integration and consideration of an elliptic shape for ellipticity function in the limit of large aspect ratio and zero shift of magnetic flux surfaces. Having the fraction of the trapped particles, by ,following the formulation and using an appropriate model in various collisional regimes, the neoclassical conductivity of plasma in Damavand Tokamak is obtained and the respective variations have been found. The presented results can exploit the computation of transport and other quantities of Damavand Tokamak
Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST
Henderson, S. S.; Garzotti, L.; Casson, F. J.; Dickinson, D.; Fox, M. F. J.; O'Mullane, M.; Patel, A.; Roach, C. M.; Summers, H. P.; Valovič, M.; The MAST Team
2014-09-01
Time-dependent helium gas puff experiments have been performed on the Mega Ampère Spherical Tokamak (MAST) during a two point plasma current scan in L-mode and a confinement scan at 900 kA. An evaluation of the He II (n = 4 → 3) spectrum line induced by charge exchange suggests anomalous rates of diffusion and inward convection in the outer regions of both L-mode plasmas. Similar rates of diffusion are found in the H-mode plasma, however these rates are consistent with neoclassical predictions. The anomalous inward pinch found in the core of L-mode plasmas is also not apparent in the H-mode core. Linear gyrokinetic simulations of one flux surface in L-mode using the GS2 and GKW codes find that equilibrium flow shear is sufficient to stabilize ITG modes, consistent with beam emission spectroscopy (BES) observations, and suggest that collisionless TEMs may dominate the anomalous helium particle transport. A quasilinear estimate of the dimensionless peaking factor associated with TEMs is in good agreement with experiment. Collisionless TEMs are more stable in H-mode because the electron density gradient is flatter. The steepness of this gradient is therefore pivotal in determining the inward neoclassical particle pinch and the particle flux associated with TEM turbulence.
Directory of Open Access Journals (Sweden)
Michał Konopczyński
2013-10-01
Full Text Available We examine the long-run impact of fiscal policy on economic growth under the conditions of an economic and monetary union (EMU. The analysis is based on the neoclassical growth model of a small (in economic terms open economy in an EMU. The core assumptions are perfect capital mobility, which results in identical interest rates across the EMU, and perfect mobility of goods, which leads to the convergence of price levels. The model is based on standard neoclassical assumptions, i.e., the output is determined by the Cobb-Douglas production function with a Harrod-neutral technical progress and constant returns to scale, capital and labor receive their marginal products, etc. We show that a unique long-run equilibrium exists and is characterized by the so-called natural rate of growth. The necessary and sufficient conditions of global asymptotic stability form a system of three non-trivial inequalities. We argue that in modern economies, these conditions are satisfied, except perhaps for very short periods of time. Furthermore, we show that the golden rules of fiscal policy have the form of an alternative optimal policy that crucially depends on the relation between the real interest rate and the natural rate of growth and on the relations between five other autonomous parameters.
Lange, L. H.
1974-01-01
Five different methods for determining the maximizing condition for x(a - x) are presented. Included is the ancient Greek version and a method attributed to Fermat. None of the proofs use calculus. (LS)
Finding Maximal Quasiperiodicities in Strings
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Pedersen, Christian N. S.
2000-01-01
of length n in time O(n log n) and space O(n). Our algorithm uses the suffix tree as the fundamental data structure combined with efficient methods for merging and performing multiple searches in search trees. Besides finding all maximal quasiperiodic substrings, our algorithm also marks the nodes......Apostolico and Ehrenfeucht defined the notion of a maximal quasiperiodic substring and gave an algorithm that finds all maximal quasiperiodic substrings in a string of length n in time O(n log2 n). In this paper we give an algorithm that finds all maximal quasiperiodic substrings in a string...... in the suffix tree that have a superprimitive path-label....
Salvio, Alberto; Strumia, Alessandro; Urbano, Alfredo
2016-01-01
Motivated by the 750 GeV diphoton excess found at LHC, we compute the maximal width into $\\gamma\\gamma$ that a neutral scalar can acquire through a loop of charged fermions or scalars as function of the maximal scale at which the theory holds, taking into account vacuum (meta)stability bounds. We show how an extra gauge symmetry can qualitatively weaken such bounds, and explore collider probes and connections with Dark Matter.
Is the Aluminum Hypothesis Dead?
2014-01-01
The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729
Effective monopole potential for SU(2) lattice gluodynamics in spatial maximal Abelian gauge
International Nuclear Information System (INIS)
Chernodub, M.N.; Polikarpov, M.I.; Veselov, A.I.
1999-01-01
We investigate the dual superconductor hypothesis in finite-temperature SU(2) lattice gluodynamics in the Spatial Maximal Abelian gauge. This gauge is more physical than the ordinary Maximal Abelian gauge due to absence of non-localities in temporal direction. We shown numerically that in the Spatial Maximal Abelian gauge the probability distribution of the abelian monopole field is consistent with the dual superconductor mechanism of confinement [ru
Gain maximization in a probabilistic entanglement protocol
di Lorenzo, Antonio; Esteves de Queiroz, Johnny Hebert
Entanglement is a resource. We can therefore define gain as a monotonic function of entanglement G (E) . If a pair with entanglement E is produced with probability P, the net gain is N = PG (E) - (1 - P) C , where C is the cost of a failed attempt. We study a protocol where a pair of quantum systems is produced in a maximally entangled state ρm with probability Pm, while it is produced in a partially entangled state ρp with the complementary probability 1 -Pm . We mix a fraction w of the partially entangled pairs with the maximally entangled ones, i.e. we take the state to be ρ = (ρm + wUlocρpUloc+) / (1 + w) , where Uloc is an appropriate unitary local operation designed to maximize the entanglement of ρ. This procedure on one hand reduces the entanglement E, and hence the gain, but on the other hand it increases the probability of success to P =Pm + w (1 -Pm) , therefore the net gain N may increase. There may be hence, a priori, an optimal value for w, the fraction of failed attempts that we mix in. We show that, in the hypothesis of a linear gain G (E) = E , even assuming a vanishing cost C -> 0 , the net gain N is increasing with w, therefore the best strategy is to always mix the partially entangled states. Work supported by CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico, proc. 311288/2014-6, and by FAPEMIG, Fundação de Amparo à Pesquisa de Minas Gerais, proc. IC-FAPEMIG2016-0269 and PPM-00607-16.
Directory of Open Access Journals (Sweden)
A. Garmroodi Asil
2017-09-01
To further reduce the sulfur dioxide emission of the entire refining process, two scenarios of acid gas or air preheats are investigated when either of them is used simultaneously with the third enrichment scheme. The maximum overall sulfur recovery efficiency and highest combustion chamber temperature is slightly higher for acid gas preheats but air preheat is more favorable because it is more benign. To the best of our knowledge, optimization of the entire GTU + enrichment section and SRU processes has not been addressed previously.
Directory of Open Access Journals (Sweden)
Luigi Pasinetti
2012-10-01
Full Text Available The paper surveys the main theories of income distribution in their relationship with the theories of economic growth. First, the Classical approach is considered, focusing on the Ricardian theory. Then the neoclassical theory is discussed, highlighting its origins (Bohm-Bawerk, Wicksell, Clark and the role of the aggregate production function. The emergence of a "Keynesian" theory of income distribution in the wake of Harrod's model of growth is then recalled together with the surprising resurgence of the neoclassical theory (following the contributions of Solow and Meade. But, as the paper shows, the neoclassical theory of income distribution lacks logical consistency and has shaky foundations, as has been revealed by the severe critiques moved to the neoclassical production function. Mainstream economic literature circumvents this problem by simply ignoring it; while the models of endogenous growth exclude the issue of distribution theory from their consideration. However, while mainstream economics bypasses the problems of income distribution, this is too relevant an issue to be ignored and a number of new research lines, briefly surveyed, try new approaches to it. JEL Codes: O41, E25Keywords: Distribution, Economic Growth, Growth, Income Distribution, Income
Ayten, B.; Westerhof, E.; ASDEX Upgrade team,
2014-01-01
Due to the smallness of the volumes associated with the flux surfaces around the O-point of a magnetic island, the electron cyclotron power density applied inside the island for the stabilization of neoclassical tearing modes (NTMs) can exceed the threshold for non-linear effects as derived
Maximizing Entropy over Markov Processes
DEFF Research Database (Denmark)
Biondi, Fabrizio; Legay, Axel; Nielsen, Bo Friis
2013-01-01
The channel capacity of a deterministic system with confidential data is an upper bound on the amount of bits of data an attacker can learn from the system. We encode all possible attacks to a system using a probabilistic specification, an Interval Markov Chain. Then the channel capacity...... as a reward function, a polynomial algorithm to verify the existence of an system maximizing entropy among those respecting a specification, a procedure for the maximization of reward functions over Interval Markov Chains and its application to synthesize an implementation maximizing entropy. We show how...... to use Interval Markov Chains to model abstractions of deterministic systems with confidential data, and use the above results to compute their channel capacity. These results are a foundation for ongoing work on computing channel capacity for abstractions of programs derived from code....
Maximizing entropy over Markov processes
DEFF Research Database (Denmark)
Biondi, Fabrizio; Legay, Axel; Nielsen, Bo Friis
2014-01-01
The channel capacity of a deterministic system with confidential data is an upper bound on the amount of bits of data an attacker can learn from the system. We encode all possible attacks to a system using a probabilistic specification, an Interval Markov Chain. Then the channel capacity...... as a reward function, a polynomial algorithm to verify the existence of a system maximizing entropy among those respecting a specification, a procedure for the maximization of reward functions over Interval Markov Chains and its application to synthesize an implementation maximizing entropy. We show how...... to use Interval Markov Chains to model abstractions of deterministic systems with confidential data, and use the above results to compute their channel capacity. These results are a foundation for ongoing work on computing channel capacity for abstractions of programs derived from code. © 2014 Elsevier...
Theory of neoclassical tearing modes and its application to ITER-FEAT
International Nuclear Information System (INIS)
Pustovitov, V.D.; Mikhailovskii, A.B.; Konovalov, S.V.; Zvonkov, A.V.; Kobayashi, N.; Mukhovatov, V.S.
2001-01-01
Neoclassical tearing modes (NTM) can be responsible for beta limitation in long-pulse ITER discharges. The excitation and growth of NTM are governed by the competing bootstrap current, polarization current and so-called Δ' effects. Also, the magnetic well and Electron Cyclotron Current Drive (ECCD) can stabilize the NTM. We study analytically and numerically all the effects with a particular emphasis on the polarization current in the analytical part of our study. We show that the polarization current description requires a generalized transport theory including the hyperviscosity, electron pressure gradient and, as well, the finite ion Larmor radius effects in the perpendicular current. The profile function nonstationarity must be taken into account for calculation of the island rotation frequency. Results of numerical simulation of NTM suppression by modulated ECCD in ITER are presented. (author)
Bi-fluid and neoclassical effect on a Double-Tearing mode in Tore Supra
Energy Technology Data Exchange (ETDEWEB)
Maget, Patrick, E-mail: patrick.maget@cea.fr; Garbet, Xavier; Février, Olivier; Ségui, Jean-Luc [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France); Lütjens, Hinrich; Luciani, Jean-François [Centre de Physique Théorique, Ecole Polytechnique, CNRS (France)
2014-06-15
Tearing modes associated to hollow current profiles are prone to grow in moderate performance plasmas and often constrain the realization of non-inductive discharges in the Tore Supra tokamak, where long pulse duration is performed using Lower Hybrid waves for providing most of the plasma current. The prediction of MHD boundaries in such scenarios is complicated by the importance of diamagnetic effects, combined with curvature stabilization, which determine the stability of these modes. We show that diamagnetic effects, as well as neoclassical forces, are playing a key role in the linear and nonlinear regimes of Double-Tearing Modes on q = 5/3 and q = 2 in these experimental conditions. Detailed comparison with experimental measurements, combined with a scaling in plasma resistivity, give constraints about the experimental equilibrium. Resistive-Interchange Modes destabilized by diamagnetic rotation could also play a role in degrading the energy confinement in the negative magnetic shear region.
L-H transition dynamics in fluid turbulence simulations with neoclassical force balance
Energy Technology Data Exchange (ETDEWEB)
Chôné, L. [Aix–Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Beyer, P.; Fuhr, G.; Benkadda, S. [Aix–Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Sarazin, Y.; Bourdelle, C. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)
2014-07-15
Spontaneous transport barrier generation at the edge of a magnetically confined plasma is reproduced in flux-driven three-dimensional fluid simulations of electrostatic turbulence. Here, the role on the radial electric field of collisional friction between trapped and passing particles is shown to be the key ingredient. Especially, accounting for the self-consistent and precise dependence of the friction term on the actual plasma temperature allows for the triggering of a transport barrier, provided that the input power exceeds some threshold. In addition, the barrier is found to experience quasi-periodic relaxation events, reminiscent of edge localised modes. These results put forward a possible key player, namely, neoclassical physics via radial force balance, for the low- to high-confinement regime transition observed in most of controlled fusion devices.
Wang, Xiaojing; Yu, Qingquan; Zhang, Xiaodong; Zhang, Yang; Zhu, Sizheng; Wang, Xiaoguang; Wu, Bin
2018-04-01
Numerical studies on the stabilization of neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD) have been carried out based on reduced MHD equations, focusing on the amount of the required driven current for mode stabilization and the comparison with analytical results. The dependence of the minimum driven current required for NTM stabilization on some parameters, including the bootstrap current density, radial width of the driven current, radial deviation of the driven current from the resonant surface, and the island width when applying ECCD, are studied. By fitting the numerical results, simple expressions for these dependences are obtained. Analysis based on the modified Rutherford equation (MRE) has also been carried out, and the corresponding results have the same trend as numerical ones, while a quantitative difference between them exists. This difference becomes smaller when the applied radio frequency (rf) current is smaller.
Improved localisation of neoclassical tearing modes by combining multiple diagnostic estimates
Rapson, C. J.; Fischer, R.; Giannone, L.; Maraschek, M.; Reich, M.; Treutterer, W.; The ASDEX Upgrade Team
2017-07-01
Neoclassical tearing modes (NTMs) strongly degrade confinement in tokamaks, and are a leading cause of disruptions. They can be stabilised by targeted electron cyclotron current drive (ECCD), however the effectiveness of ECCD depends strongly on the accuracy or misalignment between ECCD and the NTM. The first step to ensure minimal misalignment is a good estimate of the NTM location. In previous NTM control experiments, three methods have been used independently to estimate the NTM location: the magnetic equilibrium, correlation between magnetic and spatially-resolved temperature fluctuations, and the amplitude response of the NTM to nearby ECCD. This submission describes an algorithm which has been designed to fuse these three estimates into one, taking into account many of the characteristics of each diagnostic. Although the method diverges from standard data fusion methods, results from simulation and experiment confirm that the algorithm achieves its stated goal of providing an estimate that is more reliable and accurate than any of the individual estimates.
High beta plasma confinement and neoclassical effects in a small aspect ratio reversed field pinch
International Nuclear Information System (INIS)
Hayase, K.; Sugimoto, H.; Ashida, H.
2003-01-01
The high β equilibrium and stability of a reversed field pinch (RFP) configuration with a small aspect ratio are theoretically studied. The equilibrium profile, high beta limit and the bootstrap current effect on those are calculated. The Mercier stable critical β decreases with 1/A, but β∼0.2 is permissible at A=2 with help of edge current profile modification. The effect of bootstrap current is evaluated for various pressure and current profiles and cross-sectional shapes of plasma by a self-consistent neoclassical PRSM equilibrium formulation. The high bootstrap current fraction (F bs ) increases the shear stabilization effect in the core region, which enhances significantly the stability β limit compared with that for the classical equilibrium. These features of small aspect ratio RFP, high β and high F bs , and a possibly easier access to the quasi-single helicity state beside the intrinsic compact structure are attractive for the feasible economical RFP reactor concept. (author)
Pfirsch–Schlüter neoclassical heavy impurity transport in a rotating plasma
International Nuclear Information System (INIS)
Belli, E A; Candy, J; Angioni, C
2014-01-01
In this work, we extend previous analytic theories for the neoclassical transport of a trace heavy impurity in a rotating plasma in the Pfirsch–Schlüter regime. The complete diffusive and convective components of the ambipolar particle flux are derived. The solution is valid for arbitrary impurity charge and impurity Mach number and for general geometry. Inclusion of finite main-ion temperature gradient effects is shown in the small ion Mach number limit. A simple interpolation formula is derived for the case of high impurity charge and circular geometry. While an enhancement of the diffusion coefficient is found for order one impurity Mach number, a reduction due to the rotation-driven poloidal asymmetry in the density occurs for very large Mach number. (paper)
Directory of Open Access Journals (Sweden)
David H. Miller
2016-05-01
Full Text Available In September 1928 Anton Webern wrote to publisher Emil Hertzka to report on the composition of a work “in the spirit of some of Bach’s Brandenburg Concertos.” In June 1934 that work stood completed as the Concerto for Nine Instruments, Op. 24. While Op. 24 has been celebrated as a paradigmatic example of Webern’s forward-looking serial techniques, it simultaneously exhibits a strong neoclassical influence, as Kathryn Bailey (1991 has demonstrated in her study of sonata and ritornello principles in the Concerto’s first movement. Neoclassical models may have also played a role in dramatically shifting conceptions of instrumentation and genre evident in sketches from the work’s extended period of composition, during which time it transformed from a piece for large symphonic orchestra, to a concerto for solo piano with orchestral accompaniment, to a concerto grosso with a continuo-like piano part. The dramatic shifts found in the sketches are best understood in relation to Webern’s compositional activities in the decade preceding Op. 24. During this period, Webern revised several of his pre-World War I orchestral compositions, reducing the size and diversity of the ensembles with an eye towards Fasslichkeit (“comprehensibility”; a similar goal motivated the arrangements he produced for Arnold Schoenberg’s Society for Private Musical Performances. When considered alongside an instrumentation-centric view of the sketches for Op. 24, these activities suggest an intriguing view of the Concerto. If its twelve-tone row marks Op. 24 as an apex of Webern’s serial technique, its instrumentation makes it an apex of his neoclassicism.In September 1928 Anton Webern wrote to publisher Emil Hertzka to report on the composition of a work “in the spirit of some of Bach’s Brandenburg Concertos.” In June 1934 that work stood completed as the Concerto for Nine Instruments, Op. 24. While Op. 24 has been celebrated as a paradigmatic example
On the interplay between neoclassical tearing modes and nonlocal transport in toroidal plasmas
Ji, X. Q.; Xu, Y.; Hidalgo, C.; Diamond, P. H.; Liu, Yi; Pan, O.; Shi, Z. B.; Yu, D. L.
2016-09-01
This Letter presents the first observation on the interplay between nonlocal transport and neoclassical tearing modes (NTMs) during transient nonlocal heat transport events in the HL-2A tokamak. The nonlocality is triggered by edge cooling and large-scale, inward propagating avalanches. These lead to a locally enhanced pressure gradient at the q = 3/2 (or 2/1) rational surface and hence the onset of the NTM in relatively low β plasmas (βN < 1). The NTM, in return, regulates the nonlocal transport by truncation of avalanches by local sheared toroidal flows which develop near the magnetic island. These findings have direct implications for understanding the dynamic interaction between turbulence and large-scale mode structures in fusion plasmas.
International Nuclear Information System (INIS)
Yu, Q.; Zhang, X.D.; Guenter, S.
2004-01-01
Numerical modeling on the stabilization of neoclassical tearing modes by localized radio frequency (rf) current drive has been carried out to study the effects of various wave and plasma parameters on the stabilization and the associated physics. The change of the rf current profile due to the magnetic island has been taken into account by modeling the two-dimensional transport of the fast electrons induced by the rf wave. It is found that, when the rf deposition width is much larger than the island width, the modulated rf current drive to deposit the rf current around the island's o point has a stronger stabilizing effect than a nonmodulated one. The slowing down time of the fast electrons and the initial island width when applying the rf wave are also found to be important in determining the stabilizing effect
International Nuclear Information System (INIS)
La Haye, R.J.; Ferron, J.R.; Humphreys, D.A.; Luce, T.C.; Petty, C.C.; Prater, R.; Strait, E.J.; Welander, A.S.
2008-01-01
ITER will rely on electron cyclotron stabilization of neoclassical tearing mode islands. The large size and low torque applied in ITER imply slow plasma rotation and susceptibility to island locking by the resistive wall; locking is likely to lead to a loss of the high confinement H-mode, a beta collapse and possibly disruption. 'Front' steering of the launcher, with narrower electron cyclotron current drive (ECCD), has resolved the issue in 'remote' steering of the driven current being too broad and relatively ineffective. However, narrower current drive places demands on alignment of the current drive on the rational surface that is being stabilized. DIII-D alignment techniques with and without (preemptive) an island are reviewed. The results are used to check models for the effect of misalignment and are then applied to ITER. Criteria for accuracy of alignment as a function of injected power and for the necessary time response of the controller are presented
Energy Technology Data Exchange (ETDEWEB)
Goumiri, I. R. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Rowley, C. W. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Sabbagh, S. A. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Gates, D. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Boyer, M. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Andre, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kolemen, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Taira, K. [Florida State Univ, Dept Mech Engn, Tallahassee, FL USA.
2016-02-19
A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.
Onset of the radial electric field oscillations in the neoclassical plasmas
International Nuclear Information System (INIS)
Liu, C.S.; Novakovskii, S.V.; Sagdeev, R.Z.; Galeev, A.A.
1996-01-01
It is shown that the relaxation of the radial electric field in the tokomak plasmas towards its neoclassical value is accompanied by the fast oscillations of the order of the ion transient frequency V T /qR. This happens during the transition from the Pfirsch-Schluter collisional regime to the plateau regime at v c qR/V T ≤ c cr ≤ 1. The investigation has been performed with the help of the specially developed numerical code for solution of the nonsteady-state drift kinetic equation with the exact collisional term in the Hirshman-Sigmar-Clarke form. Comparison with the analytical results, corresponding to the regime of the very low collisions as well as with previous approximate models for the plateau regime will also be reported
International Nuclear Information System (INIS)
Gervasini, G.; Lazzaro, E.; Minardi, E.
1996-01-01
In accordance with the conventional ordering of neoclassical theory, poloidal and toroidal accelerations with constant parallel flow can be driven by heat transport in the absence of external momentum input and with vanishing parallel viscous stress. In a transient phase in which the heat transport is the primary source of the time dependence, the torque generating the rotation is provided at third order in the adiabatic expansion by the surface-averaged (non ambipolar) displacement current, which in also responsible for charge build-up and for the radial electric field. The heat transport equation has been solved in a narrow layer interfaced with the intensely heated plasma core through heat flux continuity, assuming neoclassical multi collisional coefficients with self-consistent suppression mechanism of anomalous transport. Starting from low temperature in the edge layer, a strong temperature gradient, a mass poloidal rotation in the ion direction and a strongly negative sheared radial electric field can be generated, in agreement with the observations, and reach a stationary state after a displacement current-dominated triggering phase (intrinsically non-ambipolar) lasting few milliseconds. Momentum input becomes important on longer time scale and is responsible for the toroidal rotation, decoupled from temperature gradient and for a further development of the radial electric field. The results show the ability of edge transport processes to adapt flexibly to a high temperature imposed on the inner side of the edge layer and support the view that the edge processes are a integral part of a more fundamental global process involving possibly an internal bifurcation of state
Validation of the kinetic-turbulent-neoclassical theory for edge intrinsic rotation in DIII-D
Ashourvan, Arash; Grierson, B. A.; Battaglia, D. J.; Haskey, S. R.; Stoltzfus-Dueck, T.
2018-05-01
In a recent kinetic model of edge main-ion (deuterium) toroidal velocity, intrinsic rotation results from neoclassical orbits in an inhomogeneous turbulent field [T. Stoltzfus-Dueck, Phys. Rev. Lett. 108, 065002 (2012)]. This model predicts a value for the toroidal velocity that is co-current for a typical inboard X-point plasma at the core-edge boundary (ρ ˜ 0.9). Using this model, the velocity prediction is tested on the DIII-D tokamak for a database of L-mode and H-mode plasmas with nominally low neutral beam torque, including both signs of plasma current. Values for the flux-surface-averaged main-ion rotation velocity in the database are obtained from the impurity carbon rotation by analytically calculating the main-ion—impurity neoclassical offset. The deuterium rotation obtained in this manner has been validated by direct main-ion measurements for a limited number of cases. Key theoretical parameters of ion temperature and turbulent scale length are varied across a wide range in an experimental database of discharges. Using a characteristic electron temperature scale length as a proxy for a turbulent scale length, the predicted main-ion rotation velocity has a general agreement with the experimental measurements for neutral beam injection (NBI) powers in the range PNBI balanced—but high powered—NBI, the net injected torque through the edge can exceed 1 Nm in the counter-current direction. The theory model has been extended to compute the rotation degradation from this counter-current NBI torque by solving a reduced momentum evolution equation for the edge and found the revised velocity prediction to be in agreement with experiment. Using the theory modeled—and now tested—velocity to predict the bulk plasma rotation opens up a path to more confidently projecting the confinement and stability in ITER.
Hypothesis Designs for Three-Hypothesis Test Problems
Yan Li; Xiaolong Pu
2010-01-01
As a helpful guide for applications, the alternative hypotheses of the three-hypothesis test problems are designed under the required error probabilities and average sample number in this paper. The asymptotic formulas and the proposed numerical quadrature formulas are adopted, respectively, to obtain the hypothesis designs and the corresponding sequential test schemes under the Koopman-Darmois distributions. The example of the normal mean test shows that our methods are qu...
International Nuclear Information System (INIS)
Wang, W. X.; Hahm, T. S.; Ethier, S.; Rewoldt, G.; Lee, W. W.; Tang, W. M.; Kaye, S. M.; Diamond, P. H.
2009-01-01
A significant inward flux of toroidal momentum is found in global gyrokinetic simulations of ion temperature gradient turbulence, leading to core plasma rotation spin-up. The underlying mechanism is identified to be the generation of residual stress due to the k parallel symmetry breaking induced by global quasistationary zonal flow shear. Simulations also show a significant off-diagonal element associated with the ion temperature gradient in the neoclassical momentum flux, while the overall neoclassical flux is small. In addition, the residual turbulence found in the presence of strong ExB flow shear may account for neoclassical-level ion heat and anomalous momentum transport widely observed in experiments
Chamaebatiaria millefolium (Torr.) Maxim.: fernbush
Nancy L. Shaw; Emerenciana G. Hurd
2008-01-01
Fernbush - Chamaebatiaria millefolium (Torr.) Maxim. - the only species in its genus, is endemic to the Great Basin, Colorado Plateau, and adjacent areas of the western United States. It is an upright, generally multistemmed, sweetly aromatic shrub 0.3 to 2 m tall. Bark of young branches is brown and becomes smooth and gray with age. Leaves are leathery, alternate,...
Taylor, S. R.
1984-01-01
The concept that the Moon was fissioned from the Earth after core separation is the most readily testable hypothesis of lunar origin, since direct comparisons of lunar and terrestrial compositions can be made. Differences found in such comparisons introduce so many ad hoc adjustments to the fission hypothesis that it becomes untestable. Further constraints may be obtained from attempting to date the volatile-refractory element fractionation. The combination of chemical and isotopic problems suggests that the fission hypothesis is no longer viable, and separate terrestrial and lunar accretion from a population of fractionated precursor planetesimals provides a more reasonable explanation.
Maximal near-field radiative heat transfer between two plates
Nefzaoui, Elyes; Ezzahri, Younès; Drévillon, Jérémie; Joulain, Karl
2013-09-01
Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the radiative heat flux are reported and compared to real materials usually considered in similar studies, silicon carbide and heavily doped silicon in this case. Results are obtained by exact and approximate (in the extreme near-field regime and the electrostatic limit hypothesis) calculations. The two methods are compared in terms of accuracy and CPU resources consumption. Their differences are explained according to a mesoscopic description of nearfield radiative heat transfer. Finally, the frequently assumed hypothesis which states a maximal radiative heat transfer when the two semi-infinite planes are of identical materials is numerically confirmed. Its subsequent practical constraints are then discussed. Presented results enlighten relevant paths to follow in order to choose or design materials maximizing nano-TPV devices performances.
Evaluating the Stage Learning Hypothesis.
Thomas, Hoben
1980-01-01
A procedure for evaluating the Genevan stage learning hypothesis is illustrated by analyzing Inhelder, Sinclair, and Bovet's guided learning experiments (in "Learning and the Development of Cognition." Cambridge: Harvard University Press, 1974). (Author/MP)
The Purchasing Power Parity Hypothesis:
African Journals Online (AJOL)
2011-10-02
Oct 2, 2011 ... reject the unit root hypothesis in real exchange rates may simply be due to the shortness ..... Violations of Purchasing Power Parity and Their Implications for Efficient ... Official Intervention in the Foreign Exchange Market:.
IMNN: Information Maximizing Neural Networks
Charnock, Tom; Lavaux, Guilhem; Wandelt, Benjamin D.
2018-04-01
This software trains artificial neural networks to find non-linear functionals of data that maximize Fisher information: information maximizing neural networks (IMNNs). As compressing large data sets vastly simplifies both frequentist and Bayesian inference, important information may be inadvertently missed. Likelihood-free inference based on automatically derived IMNN summaries produces summaries that are good approximations to sufficient statistics. IMNNs are robustly capable of automatically finding optimal, non-linear summaries of the data even in cases where linear compression fails: inferring the variance of Gaussian signal in the presence of noise, inferring cosmological parameters from mock simulations of the Lyman-α forest in quasar spectra, and inferring frequency-domain parameters from LISA-like detections of gravitational waveforms. In this final case, the IMNN summary outperforms linear data compression by avoiding the introduction of spurious likelihood maxima.
International Nuclear Information System (INIS)
Ferrandis, Javier
2005-01-01
The current experimental determination of the absolute values of the CKM elements indicates that 2 vertical bar V ub /V cb V us vertical bar =(1-z), with z given by z=0.19+/-0.14. This fact implies that irrespective of the form of the quark Yukawa matrices, the measured value of the SM CP phase β is approximately the maximum allowed by the measured absolute values of the CKM elements. This is β=(π/6-z/3) for γ=(π/3+z/3), which implies α=π/2. Alternatively, assuming that β is exactly maximal and using the experimental measurement sin(2β)=0.726+/-0.037, the phase γ is predicted to be γ=(π/2-β)=66.3 o +/-1.7 o . The maximality of β, if confirmed by near-future experiments, may give us some clues as to the origin of CP violation
Strategy to maximize maintenance operation
Espinoza, Michael
2005-01-01
This project presents a strategic analysis to maximize maintenance operations in Alcan Kitimat Works in British Columbia. The project studies the role of maintenance in improving its overall maintenance performance. It provides strategic alternatives and specific recommendations addressing Kitimat Works key strategic issues and problems. A comprehensive industry and competitive analysis identifies the industry structure and its competitive forces. In the mature aluminium industry, the bargain...
Scalable Nonlinear AUC Maximization Methods
Khalid, Majdi; Ray, Indrakshi; Chitsaz, Hamidreza
2017-01-01
The area under the ROC curve (AUC) is a measure of interest in various machine learning and data mining applications. It has been widely used to evaluate classification performance on heavily imbalanced data. The kernelized AUC maximization machines have established a superior generalization ability compared to linear AUC machines because of their capability in modeling the complex nonlinear structure underlying most real world-data. However, the high training complexity renders the kernelize...
FLOUTING MAXIMS IN INDONESIA LAWAK KLUB CONVERSATION
Directory of Open Access Journals (Sweden)
Rahmawati Sukmaningrum
2017-04-01
Full Text Available This study aims to identify the types of maxims flouted in the conversation in famous comedy show, Indonesia Lawak Club. Likewise, it also tries to reveal the speakers‘ intention of flouting the maxim in the conversation during the show. The writers use descriptive qualitative method in conducting this research. The data is taken from the dialogue of Indonesia Lawak club and then analyzed based on Grice‘s cooperative principles. The researchers read the dialogue‘s transcripts, identify the maxims, and interpret the data to find the speakers‘ intention for flouting the maxims in the communication. The results show that there are four types of maxims flouted in the dialogue. Those are maxim of quality (23%, maxim of quantity (11%, maxim of manner (31%, and maxim of relevance (35. Flouting the maxims in the conversations is intended to make the speakers feel uncomfortable with the conversation, show arrogances, show disagreement or agreement, and ridicule other speakers.
International Nuclear Information System (INIS)
Li, D.
2001-01-01
The neoclassical and double tearing modes have been analyzed with related new phenomena in the reversed magnetic shear tokamak plasmas. The instability threshold, and the linear and nonlinear evolution are derived for the neoclassical tearing modes. It is found that the perturbed bootstrap current in the resistive layer has a stabilizing effect while the equilibrium bootstrap current in the outer region can destabilize the modes. The dispersion relation is derived for the double tearing mode. It is found that the onset of ''annular crash'' is due to the fast reconnection of the hot and cold islands, triggered by the interaction of both branches. The onset of ''core crash'' is mainly due to the coalescence between the hot islands, triggered by the explosive growth of the inner branch. (author)
International Nuclear Information System (INIS)
Li Ding
1999-01-01
The neoclassical and double tearing modes have been analyzed with related new phenomena in the reversed magnetic shear tokamak plasmas. The instability threshold, and the linear and nonlinear evolution are derived for the neoclassical tearing modes. It is found that the perturbed bootstrap current in the resistive layer has a stabilizing effect while the equilibrium bootstrap current in the outer region can destabilize the modes. The dispersion relation is derived for the double tearing mode. It is found that the onset of 'annular crash' is due to the fast reconnection of the hot and cold islands, triggered by the interaction of both branches. The onset of 'core crash' is mainly due to the coalescence between the hot islands, triggered by the explosive growth of the inner branch. (author)
International Nuclear Information System (INIS)
PETTY, CC; LAHAYE, LA; LUCE, TC; HUMPHREYS, DA; HYATT, AW; PRATER, R; STRAIT, EJ; WADE, MR
2003-01-01
A271 COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. The first suppression of the important and deleterious m=2/n=1 neoclassical tearing mode (NTM) is reported using electron cyclotron current drive (ECCD) to replace the ''missing'' bootstrap current in the island O-point. Experiments on the DIII-D tokamak verify the maximum shrinkage of the m=2/n=1 island occurs when the ECCD location coincides with the q = 2 surface. The DIII-D plasma control system is put into search and suppress mode to make small changes in the toroidal field to find and lock onto the optimum position, based on real time measurements of dB θ /dt, for complete m=2/n=1 NTM suppression by ECCD. The requirements on the ECCD for complete island suppression are well modeled by the modified Rutherford equation for the DIII-D plasma conditions
International Nuclear Information System (INIS)
Nishimura, Shin
2009-01-01
Effects of the perturbed magnetic field with low toroidal mode numbers (n) are considered. One cause of this type of perturbation, which has recently been studied in tokamaks, is MHD-activities. In helical/stellarator, this low-n perturbation is sometimes artificially added for island diverters. In viewpoint of the neoclassical viscosities, these perturbed magnetic fields affect on both of bounce center drifts of toroidally trapped and ripple-trapped particles. However, in usual neoclassical analyses in helical/stellarator devices assuming periodic magnetic field strength, these effects had not been studied. For future studies in helical/stellarator devices, a method to use bounce-averaged drift kinetic equation for the toroidally trapped particles is proposed. (author)
Effects of finite-β and radial electric fields on neoclassical transport in the Large Helical Device
International Nuclear Information System (INIS)
Kanno, R.; Nakajima, N.; Sugama, H.; Okamoto, M.; Ogawa, Y.
1997-01-01
Effects of finite-β and radial electric fields on the neoclassical transport in the Large Helical Device are investigated with the DKES (Drift Kinetic Equation Solver) code. In the finite-β configuration, even orbits of deeply trapped particles deviate significantly from magnetic flux surfaces. Thus, neoclassical ripple transport coefficients in the finite-β configuration are several times larger than those in the vacuum configuration under the same condition of temperatures and radial electric fields. When the plasma temperature is several keV, a bifurcation of the electric fields appears under the ambipolarity condition, and sufficient large radial electric fields can be generated. As a result, the ExB drift rectifies orbits of particles and improves significantly the transport coefficients in the finite-β configuration. (author)
The atomic hypothesis: physical consequences
International Nuclear Information System (INIS)
Rivas, Martin
2008-01-01
The hypothesis that matter is made of some ultimate and indivisible objects, together with the restricted relativity principle, establishes a constraint on the kind of variables we are allowed to use for the variational description of elementary particles. We consider that the atomic hypothesis not only states the indivisibility of elementary particles, but also that these ultimate objects, if not annihilated, cannot be modified by any interaction so that all allowed states of an elementary particle are only kinematical modifications of any one of them. Therefore, an elementary particle cannot have excited states. In this way, the kinematical group of spacetime symmetries not only defines the symmetries of the system, but also the variables in terms of which the mathematical description of the elementary particles can be expressed in either the classical or the quantum mechanical description. When considering the interaction of two Dirac particles, the atomic hypothesis restricts the interaction Lagrangian to a kind of minimal coupling interaction
International Nuclear Information System (INIS)
La Haye, R.J.; Isayama, A.; Maraschek, M.
2009-01-01
The system planned for electron cyclotron current drive (ECCD) in ITER can mitigate the deleterious effects of neoclassical tearing modes (NTMs) provided that either adequate alignment of the ECCD to the rational surface is maintained or too large a misalignment is corrected on a time scale shorter than the deleterious plasma response to 'large' islands. Resistive neoclassical tearing modes will be the principal limit on stability and performance in the ITER standard scenario as the drag from rotating island induced eddy current in the resistive wall (particularly from the m/n = 2/1 mode) can slow the plasma rotation, produce locking to the wall and cause loss of high-confinement H-mode and disruption. Continuous wave (cw) ECCD at the island rational surface is successful in stabilization and/or prevention of NTMs in ASDEX Upgrade, DIII-D and JT-60U. Modulating the ECCD so that it is absorbed only on the rotating island O-point is proving successful in recovering effectiveness in ASDEX Upgrade when the ECCD is configured for wider deposition as expected in ITER. The models for the effect of misalignment on ECCD effectiveness are applied to ITER. Tolerances for misalignment are presented to establish criteria for both the alignment (by moving mirrors in ITER) in the presence of an island, and for the accuracy of real-time ITER MHD equilibrium reconstruction in the absence of an island, i.e. alignment to the mode or to the rational surface in the absence of the mode. The narrower ECCD with front steering makes precise alignment more necessary for the most effective stabilization even though the ECCD is still relatively broad, with current density deposition (full width half maximum) almost twice the marginal island width. This places strict requirements on ECCD alignment with the expected ECCD effectiveness dropping to zero for misalignments as small as 1.7 cm. The system response time for growing islands and slowing rotation without and with ECCD (at different
Implications of the quasi-neutrality condition for neoclassical transport in stellarators
International Nuclear Information System (INIS)
Beidler, C.D.; Maassberg, H.
2005-01-01
In conventional stellarator neoclassical theory, the transport coefficients are determined so as to satisfy the so-called ambipolarity constraint on the radial particle fluxes but without regard to the additional requirement that the underlying solutions of the kinetic equation also fulfill local quasi-neutrality. This neglect is consistent with the assumption that density, n and electrostatic potential, Φ, are constant on a flux surface and is justified in the literature with analytic scaling arguments which demonstrate that quasi-neutrality introduces variations of n and Φ on a flux surface which have only a modest impact on bulk-plasma transport. The consequences for impurity transport have not been considered. In this contribution, the implications which the quasi-neutrality condition has for neoclassical transport in stellarators are investigated using a version of the General Solution of the Ripple-Averaged Kinetic Equation (GSRAKE) which accounts for the variation of Φ on flux surfaces. Solutions of the kinetic equation which simultaneously fulfill the ambipolarity and the quasi-neutrality conditions are determined iteratively using standard methods for solving systems of non-linear equations, given specified density and temperature profiles for pure hydrogen plasmas. For a conventional heliotron device, it is shown that quasi-neutrality significantly reduces the radial extent of the region in which multiple solutions of the ambipolarity condition can exist. Especially in the plasma periphery, where strong density and temperature gradients are found, the magnitude of the 'ion' root is reduced significantly leading to increased particle and energy fluxes. For strongly drift-optimized stellarators, on the other hand, bulk plasma transport is much less affected. In a small number of cases, the non-linear system of equations produces additional solutions which are not possible when only ambipolarity is enforced, but such cases are rare. Finally, it is
International Nuclear Information System (INIS)
La Haye, R.J.; Strait, E.J.; Rice, B.W.
2000-01-01
Resistive neoclassical tearing modes (NTMs) can cause the stable beta value in long pulse, high confinement plasmas to fall significantly below that predicted by ideal theory. The NTM islands which degrade confinement and limit beta are induced and sustained by helically perturbed bootstrap currents. A combination of shaping and q-profile modification is used in the DIII-D tokamak to increase this beta limit. (author)
International Nuclear Information System (INIS)
Igna Junior, A.D.
1984-01-01
The relevant parameters of two steady-state models of a plasma column, in fusion regime, were analyzed for an ideal Tokamak. The neo-classical transport theory was considered in the banana regime and in the Pfirsch-Schlueter regime. The first model proposes a correction in the numerical coefficients of the transport equations. In the other one, a poloidal current from Pfirsch-Schlueter classical diffusion is considered aiming to satisfy the pressure balance. (M.C.K.) [pt
On Maximal Non-Disjoint Families of Subsets
Directory of Open Access Journals (Sweden)
Yu. A. Zuev
2017-01-01
Full Text Available The paper studies maximal non-disjoint families of subsets of a finite set. Non-disjointness means that any two subsets of a family have a nonempty intersection. The maximality is expressed by the fact that adding a new subset to the family cannot increase its power without violating a non-disjointness condition. Studying the properties of such families is an important section of the extreme theory of sets. Along with purely combinatorial interest, the problems considered here play an important role in informatics, anti-noise coding, and cryptography.In 1961 this problem saw the light of day in the Erdos, Ko and Rado paper, which established a maximum power of the non-disjoint family of subsets of equal power. In 1974 the Erdos and Claytman publication estimated the number of maximal non-disjoint families of subsets without involving the equality of their power. These authors failed to establish an asymptotics of the logarithm of the number of such families when the power of a basic finite set tends to infinity. However, they suggested such an asymptotics as a hypothesis. A.D. Korshunov in two publications in 2003 and 2005 established the asymptotics for the number of non-disjoint families of the subsets of arbitrary powers without maximality condition of these families.The basis for the approach used in the paper to study the families of subsets is their description in the language of Boolean functions. A one-to-one correspondence between a family of subsets and a Boolean function is established by the fact that the characteristic vectors of subsets of a family are considered to be the unit sets of a Boolean function. The main theoretical result of the paper is that the maximal non-disjoint families are in one-to-one correspondence with the monotonic self-dual Boolean functions. When estimating the number of maximal non-disjoint families, this allowed us to use the result of A.A. Sapozhenko, who established the asymptotics of the number of the
Multiple sclerosis: a geographical hypothesis.
Carlyle, I P
1997-12-01
Multiple sclerosis remains a rare neurological disease of unknown aetiology, with a unique distribution, both geographically and historically. Rare in equatorial regions, it becomes increasingly common in higher latitudes; historically, it was first clinically recognized in the early nineteenth century. A hypothesis, based on geographical reasoning, is here proposed: that the disease is the result of a specific vitamin deficiency. Different individuals suffer the deficiency in separate and often unique ways. Evidence to support the hypothesis exists in cultural considerations, in the global distribution of the disease, and in its historical prevalence.
Discussion of the Porter hypothesis
International Nuclear Information System (INIS)
1999-11-01
In the reaction to the long-range vision of RMNO, published in 1996, The Dutch government posed the question whether a far-going and progressive modernization policy will lead to competitive advantages of high-quality products on partly new markets. Such a question is connected to the so-called Porter hypothesis: 'By stimulating innovation, strict environmental regulations can actually enhance competitiveness', from which statement it can be concluded that environment and economy can work together quite well. A literature study has been carried out in order to determine under which conditions that hypothesis is endorsed in the scientific literature and policy documents. Recommendations are given for further studies. refs
The thrifty phenotype hypothesis revisited
DEFF Research Database (Denmark)
Vaag, A A; Grunnet, L G; Arora, G P
2012-01-01
Twenty years ago, Hales and Barker along with their co-workers published some of their pioneering papers proposing the 'thrifty phenotype hypothesis' in Diabetologia (4;35:595-601 and 3;36:62-67). Their postulate that fetal programming could represent an important player in the origin of type 2...... of the underlying molecular mechanisms. Type 2 diabetes is a multiple-organ disease, and developmental programming, with its idea of organ plasticity, is a plausible hypothesis for a common basis for the widespread organ dysfunctions in type 2 diabetes and the metabolic syndrome. Only two among the 45 known type 2...
International Nuclear Information System (INIS)
Oikawa, T.; Suzuki, T.; Isayama, A.; Hayashi, N.; Fujita, T.; Naito, O.; Tuda, T.; Kurita, G.
2005-01-01
Evolution of the current density profile associated with magnetic island formation in a neoclassical tearing mode plasma is measured for the first time in JT-60U by using a motional Stark effect diagnostic. As the island grows, the current density profile turns flat at the radial region of the island and a hollow structure appears at the rational surface. As the island shrinks the deformed region becomes narrower and finally diminishes after the disappearance of the island. In a quiescent plasma without magnetohydrodynamic instabilities, on the other hand, no deformation is observed. The observed deformation in the current density profile associated with the tearing mode is reproduced in a time dependent transport simulation assuming the reduction of the bootstrap current in the radial region of the island. Comparison of the measurement with a calculated steady-state solution also shows that the reduction and recovery of the bootstrap current at the island explains the temporal behaviours of the current density and safety factor profiles. From the experimental observation and simulations, we reach the conclusion that the bootstrap current decreases within the island O-point
Influence of anomalous transport phenomena on onset of Neoclassical Tearing Modes in tokamaks
International Nuclear Information System (INIS)
Konovalov, S.V.; Mikhailovskii, A.B.; Shirokov, M.S.; Ozeki, T.; Takizuka, T.; Hayashi, N.
2005-01-01
Influence of anomalous perpendicular heat transport and anomalous ion perpendicular viscosity on conditions of Neoclassical Tearing Mode (NTM) onset is studied theoretically. Series of various parallel transport mechanisms competitive to anomalous cross-island heat transport in formation of the perturbed electron and ion temperature profiles within the island are considered. Analytical solutions to respective heat balance equations were found and perturbed temperature profiles were calculated rigorously. The partial contributions from the plasma electron and ion temperature perturbations in the bootstrap drive of the mode and magnetic curvature effect were then accounted in construction of a generalized transport threshold model of NTMs. Taking into account the curvature effect weakening in the generalized transport threshold model predicts notable improvement of NTM stability. The anomalous perpendicular ion viscosity was shown to modify collisionality dependence of polarization current effect reducing it to the low collisionality limit. The bootstrap drive of NTM in the presence of anomalous perpendicular ion viscosity was found to be dependent on the island rotation frequency and direction. For island rotating in direction of the electron diamagnetic drift viscosity effect was shown to be stabilizing. The role of viscosity effect grows rapidly with rise of the plasma ion temperature. (author)
Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas
2012-09-01
We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation.
Time-dependent simulations of feedback stabilization of neoclassical tearing modes in KSTAR plasmas
Energy Technology Data Exchange (ETDEWEB)
Kim, Kyungjin [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Na, Yong-Su, E-mail: ysna@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Kim, Hyun-Seok [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Maraschek, M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei München (Germany); Park, Y.S. [Department of Applied Physics and Applied Mathematics, Columbia University, New York (United States); Stober, J. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei München (Germany); Terzolo, L. [National Fusion Research Institute, Daejeon (Korea, Republic of); Zohm, H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei München (Germany)
2014-06-15
A simulation is performed for feedback stabilization of neoclassical tearing mode (NTM) by electron cyclotron current drive (ECCD) for KSTAR in preparation for experiments. An integrated numerical system is constructed by coupling plasma transport, NTM stability, and heating and current drive modules and applied to a KSTAR plasma by assuming similar experimental conditions as ASDEX Upgrade to predict NTM behaviors in KSTAR. System identification is made with database produced by predictive simulations with this integrated numerical system so that three plasma response models are extracted which describe the relation between the EC poloidal launcher angle and the island width in KSTAR. Among them, the P1DI model exhibiting the highest fit accuracy is selected for designing a feedback controller based on the classical Proportional–Integral–Derivative (PID) concept. The controller is coupled with the integrated numerical system and applied to a simulation of NTM stabilization. It is observed that the controller can search and fully stabilize the mode even though the poloidal launch angle is misaligned with the island initially.
Self-consistent perturbed equilibrium with neoclassical toroidal torque in tokamaks
International Nuclear Information System (INIS)
Park, Jong-Kyu; Logan, Nikolas C.
2017-01-01
Toroidal torque is one of the most important consequences of non-axisymmetric fields in tokamaks. The well-known neoclassical toroidal viscosity (NTV) is due to the second-order toroidal force from anisotropic pressure tensor in the presence of these asymmetries. This work shows that the first-order toroidal force originating from the same anisotropic pressure tensor, despite having no flux surface average, can significantly modify the local perturbed force balance and thus must be included in perturbed equilibrium self-consistent with NTV. The force operator with an anisotropic pressure tensor is not self-adjoint when the NTV torque is finite and thus is solved directly for each component. This approach yields a modified, non-self-adjoint Euler-Lagrange equation that can be solved using a variety of common drift-kinetic models in generalized tokamak geometry. The resulting energy and torque integral provides a unique way to construct a torque response matrix, which contains all the information of self-consistent NTV torque profiles obtainable by applying non-axisymmetric fields to the plasma. This torque response matrix can then be used to systematically optimize non-axisymmetric field distributions for desired NTV profiles. Published by AIP Publishing.
Ideal kink and neoclassical tearing mode identification in DIII-D with ECE
Zhao, Hailin; Austin, Max; Brookman, Michale; Rowan, William; La Haye, R. J.
2017-10-01
Detection of neoclassical tearing modes (NTMs), which can degrade plasma confinement or cause disruptions, is important in tokamaks. We have developed a code to cross-correlate ECE/magnetics data to get the amplitude and phase profiles of the electron temperature (Te) oscillation caused by the rotating magnetic island and/or a kink. It has been observed that the ΔTe amplitude on the two sides of the island center can be very different in some discharges. Also, a discrepancy often exists between the location of the rational q surface according to MSE-constrained EFIT and the location of island center according to ECE; this can be an issue for ECCD suppression of NTMs. We explore the possible causes of these two phenomena in terms of ECE location and calibration accuracy. By analyzing the Te fluctuation phase evolution after a large sawtooth crash which triggers an NTM, the presence of a kink-like mode before the onset of NTM can be discerned. Work supported by the US DOE under DE-FG02-97ER54415 and DE-FC02-04ER54698.
Poli, F. M.; Fredrickson, E. D.; Henderson, M. A.; Kim, S.-H.; Bertelli, N.; Poli, E.; Farina, D.; Figini, L.
2018-01-01
Time-dependent simulations are used to evolve plasma discharges in combination with a modified Rutherford equation for calculation of neoclassical tearing mode (NTM) stability in response to electron cyclotron (EC) feedback control in ITER. The main application of this integrated approach is to support the development of control algorithms by analyzing the plasma response with physics-based models and to assess how uncertainties in the detection of the magnetic island and in the EC alignment affect the ability of the ITER EC system to fulfill its purpose. Simulations indicate that it is critical to detect the island as soon as possible, before its size exceeds the EC deposition width, and that maintaining alignment with the rational surface within half of the EC deposition width is needed for stabilization and suppression of the modes, especially in the case of modes with helicity (2, 1) . A broadening of the deposition profile, for example due to wave scattering by turbulence fluctuations or not well aligned beams, could even be favorable in the case of the (2, 1)- NTM, by relaxing an over-focussing of the EC beam and improving the stabilization at the mode onset. Pre-emptive control reduces the power needed for suppression and stabilization in the ITER baseline discharge to a maximum of 5 MW, which should be reserved and available to the upper launcher during the entire flattop phase. Assuming continuous triggering of NTMs, with pre-emptive control ITER would be still able to demonstrate a fusion gain of Q=10 .
Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks
Kleiner, A.; Graves, J. P.; Brunetti, D.; Cooper, W. A.; Halpern, F. D.; Luciani, J.-F.; Lütjens, H.
2016-09-01
A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that infernal modes drive fast growing islands on neighbouring rational surfaces. Numerical simulations of such instabilities in a MAST-like configuration are performed with the initial value stability code XTOR-2F in the resistive frame. The evolution of magnetic islands are computed from XTOR-2F simulations and an analytical model is developed based on Rutherford’s theory in combination with a model of resistive infernal modes. The parameter {{Δ }\\prime} is extended from the linear phase to the non-linear phase. Additionally, the destabilising contribution due to a helically perturbed bootstrap current is considered. Comparing the numerical XTOR-2F simulations to the model, we find that coupling has a strong destabilising effect on (neoclassical) tearing modes and is able to seed 2/1 magnetic islands in situations when the standard NTM theory predicts stability.
International Nuclear Information System (INIS)
Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas
2012-01-01
We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation. (paper)
Control system of neoclassical tearing modes in real time on HL-2A tokamak
Yan, Longwen; Ji, Xiaoquan; Song, Shaodong; Xia, Fan; Xu, Yuan; Ye, Jiruo; Jiang, Min; Chen, Wenjin; Sun, Tengfei; Liang, Shaoyong; Ling, Fei; Ma, Rui; Huang, Mei; Qu, Hongpeng; Song, Xianming; Yu, Deliang; Shi, Zhongbin; Liu, Yi; Yang, Qingwei; Xu, Min; Duan, Xuru; Liu, Yong
2017-11-01
The stability and performance of tokamak plasmas are routinely limited by various magneto-hydrodynamic instabilities, such as neoclassical tearing modes (NTMs). This paper presents a rather simple method to control the NTMs in real time (RT) on a tokamak, including the control principle of a feedback approach for RT suppression and stabilization for the NTMs. The control system combines Mirnov, electron cyclotron emission, and soft X-ray diagnostics used for determining the NTM positions. A methodology for fast detection of 2/1 or 3/2 NTM positions with 129 × 129 grid reconstruction is elucidated. The forty poloidal angles for steering the electron cyclotron resonance heating (ECRH)/electron cyclotron current drive launcher are used to establish the alignment of antenna mirrors with the center of the NTM and to ensure launcher emission intersecting with the rational surface of a magnetic island. Pilot experiments demonstrate the RT control capability to trace the conventional tearing modes (CTMs) in the HL-2A tokamak. The 2/1 CTMs have been suppressed or stabilized by the ECRH power deposition on site or with the steerable launcher.
A theory of planning horizons (1: market design in a post-neoclassical world
Directory of Open Access Journals (Sweden)
Frederic B. Jennings, Jr.
2012-05-01
Full Text Available The neoclassical case supporting competitive frames and market solutions has failed to promote stable world-wide economic development. Other approaches in economics incorporate social culture, increasing returns, market power, ecological limits and complementarity, yielding broader applications for development theory. In this paper a theory of planning horizons is introduced to raise some meaningful questions about the traditional view with respect to its substitution, decreasing returns and independence assumptions. Suppositions of complementarity, increasing returns and interdependence suggest that competition is inefficient by upholding a myopic culture resistant to learning. Growth – though long believed to rise from markets and competitive values – may not derive from these sources. Instead, as civilizations advance, shifting from material wants to higher-order intangible output, they evolve from market tradeoffs (substitution and scarcity into realms of common need (complementarity and abundance. The policy implications of horizonal theory are explored, with respect to regulatory aims and economic concerns. Such an approach emphasizes strict constraints against entry barriers, ecological harm, market power abuse and ethical lapses. Social cohesion – not competition – is sought as a means to extend horizons and thereby increase efficiency, equity and ecological health. The overriding importance of horizon effects for regulatory assessment dominates other orthodox standards in economics and law. Reframing economics along horizonal lines suggests some meaningful insight on the proper design of economic systems.
Tokamak plasma transport simulation in the presence of neoclassical tearing modes
International Nuclear Information System (INIS)
Takahashi, Y.; Yamazaki, K.; Arimoto, H.; Shoji, T.; Garcia, J.
2008-01-01
For the prediction of the ITER plasmas, the effect of the neoclassical tearing mode (NTM) on the plasma confinement has been calculated using the 1.5-dimensional equilibrium and transport simulation code TOTAL. The time evolution of the NTM magnetic island has been analyzed using the modified Rutherford equation for a ITER normal shear plasma. The anomalous transport model used here is GLF23. The saturated magnetic island widths are w/a - 0.048 at 3/2 mode and w/a - 0.21 at 2/1 mode, and the reduction in fusion power output by NTM is 27% at the 3/2 mode, 82% at the 2/1 mode, and 89% at the 3/2 + 2/1 double mode. The stabilization effect of the electron cyclotron current drive (ECCD) with EC is also clarified. The threshold of ECCD power for the full stabilization is ∼10[MW] against the 3/2 mode, and ∼23[MW] against the 2/1 mode. (author)
Age structure and capital dilution effects in neo-classical growth models.
Blanchet, D
1988-01-01
Economists often over estimate capital dilution effects when applying neoclassical growth models which use age structured population and depreciation of capital stock. This occurs because capital stock is improperly characterized. A standard model which assumes a constant depreciation of capital intimates that a population growth rate equal to a negative constant savings ratio is preferable to any higher growth rate. Growth rates which are lower than a negative constant savings ratio suggest an ever growing capital/labor ratio and an ever growing standard of living, even if people do not save. This is suggested because the natural reduction of the capital stock through depreciation is slower than the population decrease which is simply unrealistic. This model overlooks the fact that low or negative growth rates result in an ageing of the capital stock, and this ageing subsequently results in an increase of the overall rate of capital depreciation. In that overly simplistic model, depreciation was assumed independent of the age of the captial stock. Incorporating depreciation as a variable into a model allows a more symmetric treatment of capital. Using models with heterogenous capital, this article explores what occurs when more than 1 kind of capital good is involved in production and when these various captial goods have different lengths of life. Applying economic models, it also examines what occurs when the length of life of capital may vary. These variations correct the negative impact that population growth can have on per capital production and consumption.
Lawther, R
2018-01-01
In this work the author lets \\Phi be an irreducible root system, with Coxeter group W. He considers subsets of \\Phi which are abelian, meaning that no two roots in the set have sum in \\Phi \\cup \\{ 0 \\}. He classifies all maximal abelian sets (i.e., abelian sets properly contained in no other) up to the action of W: for each W-orbit of maximal abelian sets we provide an explicit representative X, identify the (setwise) stabilizer W_X of X in W, and decompose X into W_X-orbits. Abelian sets of roots are closely related to abelian unipotent subgroups of simple algebraic groups, and thus to abelian p-subgroups of finite groups of Lie type over fields of characteristic p. Parts of the work presented here have been used to confirm the p-rank of E_8(p^n), and (somewhat unexpectedly) to obtain for the first time the 2-ranks of the Monster and Baby Monster sporadic groups, together with the double cover of the latter. Root systems of classical type are dealt with quickly here; the vast majority of the present work con...
Questioning the social intelligence hypothesis.
Holekamp, Kay E
2007-02-01
The social intelligence hypothesis posits that complex cognition and enlarged "executive brains" evolved in response to challenges that are associated with social complexity. This hypothesis has been well supported, but some recent data are inconsistent with its predictions. It is becoming increasingly clear that multiple selective agents, and non-selective constraints, must have acted to shape cognitive abilities in humans and other animals. The task now is to develop a larger theoretical framework that takes into account both inter-specific differences and similarities in cognition. This new framework should facilitate consideration of how selection pressures that are associated with sociality interact with those that are imposed by non-social forms of environmental complexity, and how both types of functional demands interact with phylogenetic and developmental constraints.
Maximizing benefits from resource development
International Nuclear Information System (INIS)
Skjelbred, B.
2002-01-01
The main objectives of Norwegian petroleum policy are to maximize the value creation for the country, develop a national oil and gas industry, and to be at the environmental forefront of long term resource management and coexistence with other industries. The paper presents a graph depicting production and net export of crude oil for countries around the world for 2002. Norway produced 3.41 mill b/d and exported 3.22 mill b/d. Norwegian petroleum policy measures include effective regulation and government ownership, research and technology development, and internationalisation. Research and development has been in five priority areas, including enhanced recovery, environmental protection, deep water recovery, small fields, and the gas value chain. The benefits of internationalisation includes capitalizing on Norwegian competency, exploiting emerging markets and the assurance of long-term value creation and employment. 5 figs
Maximizing synchronizability of duplex networks
Wei, Xiang; Emenheiser, Jeffrey; Wu, Xiaoqun; Lu, Jun-an; D'Souza, Raissa M.
2018-01-01
We study the synchronizability of duplex networks formed by two randomly generated network layers with different patterns of interlayer node connections. According to the master stability function, we use the smallest nonzero eigenvalue and the eigenratio between the largest and the second smallest eigenvalues of supra-Laplacian matrices to characterize synchronizability on various duplexes. We find that the interlayer linking weight and linking fraction have a profound impact on synchronizability of duplex networks. The increasingly large inter-layer coupling weight is found to cause either decreasing or constant synchronizability for different classes of network dynamics. In addition, negative node degree correlation across interlayer links outperforms positive degree correlation when most interlayer links are present. The reverse is true when a few interlayer links are present. The numerical results and understanding based on these representative duplex networks are illustrative and instructive for building insights into maximizing synchronizability of more realistic multiplex networks.
Whiplash and the compensation hypothesis.
Spearing, Natalie M; Connelly, Luke B
2011-12-01
Review article. To explain why the evidence that compensation-related factors lead to worse health outcomes is not compelling, either in general, or in the specific case of whiplash. There is a common view that compensation-related factors lead to worse health outcomes ("the compensation hypothesis"), despite the presence of important, and unresolved sources of bias. The empirical evidence on this question has ramifications for the design of compensation schemes. Using studies on whiplash, this article outlines the methodological problems that impede attempts to confirm or refute the compensation hypothesis. Compensation studies are prone to measurement bias, reverse causation bias, and selection bias. Errors in measurement are largely due to the latent nature of whiplash injuries and health itself, a lack of clarity over the unit of measurement (specific factors, or "compensation"), and a lack of appreciation for the heterogeneous qualities of compensation-related factors and schemes. There has been a failure to acknowledge and empirically address reverse causation bias, or the likelihood that poor health influences the decision to pursue compensation: it is unclear if compensation is a cause or a consequence of poor health, or both. Finally, unresolved selection bias (and hence, confounding) is evident in longitudinal studies and natural experiments. In both cases, between-group differences have not been addressed convincingly. The nature of the relationship between compensation-related factors and health is unclear. Current approaches to testing the compensation hypothesis are prone to several important sources of bias, which compromise the validity of their results. Methods that explicitly test the hypothesis and establish whether or not a causal relationship exists between compensation factors and prolonged whiplash symptoms are needed in future studies.
VIOLATION OF CONVERSATION MAXIM ON TV ADVERTISEMENTS
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Desak Putu Eka Pratiwi
2015-07-01
Full Text Available Maxim is a principle that must be obeyed by all participants textually and interpersonally in order to have a smooth communication process. Conversation maxim is divided into four namely maxim of quality, maxim of quantity, maxim of relevance, and maxim of manner of speaking. Violation of the maxim may occur in a conversation in which the information the speaker has is not delivered well to his speaking partner. Violation of the maxim in a conversation will result in an awkward impression. The example of violation is the given information that is redundant, untrue, irrelevant, or convoluted. Advertisers often deliberately violate the maxim to create unique and controversial advertisements. This study aims to examine the violation of maxims in conversations of TV ads. The source of data in this research is food advertisements aired on TV media. Documentation and observation methods are applied to obtain qualitative data. The theory used in this study is a maxim theory proposed by Grice (1975. The results of the data analysis are presented with informal method. The results of this study show an interesting fact that the violation of maxim in a conversation found in the advertisement exactly makes the advertisements very attractive and have a high value.
Real-time sawtooth control and neoclassical tearing mode preemption in ITER
Energy Technology Data Exchange (ETDEWEB)
Kim, D., E-mail: doohyun.kim@epfl.ch; Goodman, T. P.; Sauter, O. [École Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)
2014-06-15
Real-time control of multiple plasma actuators is a requirement in advanced tokamaks; for example, for burn control, plasma current profile control and MHD stabilization—electron cyclotron (EC) wave absorption is ideally suited especially for the latter. On ITER, 24 EC sources can be switched between 56 inputs at the torus. In the torus, 5 launchers direct the power to various locations across the plasma profile via 11 steerable mirrors. For optimal usage of the available power, the aiming and polarization of the beams must be adapted to the plasma configuration and the needs of the scenario. Since the EC system performs many competing tasks, present day systems should demonstrate the ability of an EC plant to deal with several targets in parallel and/or to switch smoothly between goals to attain overall satisfaction. Based on pacing and locking experiments performed on TCV (Tokamak à Configuration Variable), the real-time sawtooth control of ITER with this complex set of actuators is analyzed, as an example. It is shown that sawtooth locking and pacing are possible with various levels of powers, leading to different time delays between the end of the EC power phase and the next sawtooth crash. This timing is important since it allows use of the same launchers for neoclassical tearing mode (NTM) preemption at the q = 1.5 or 2 surface, avoiding the need to switch power between launchers. These options are presented. It is also demonstrated that increasing the total EC power does not necessarily increase the range of control because of the geometry of the launchers.
Stabilization of neoclassical tearing modes by electron cyclotron current drive in JT-60U
International Nuclear Information System (INIS)
Isayama, A.; Oyama, N.; Urano, H.; Suzuki, T.; Takechi, M.; Hayashi, N.; Nagasaki, K.; Kamada, Y.; Ide, S.; Ozeki, T.
2007-01-01
Results of active control of neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD) in JT-60U are described. Growth of an NTM with poloidal mode number m = 3 and toroidal mode number n = 2 has been suppressed by ECCD inside the sawtooth inversion radius in the co-direction, showing the possibility of the coexistence of sawtooth oscillations and a small-amplitude m/n = 3/2 NTM without large confinement degradation. Stabilization of an m/n = 2/1 NTM by ECCD at the mode rational surface has been demonstrated with a small ratio of the current density driven by the electron cyclotron (EC) wave to the local bootstrap current density (∼ 0.5). In addition, dependence of the stabilization effect on ECCD location has been investigated in detail. It has been found that an m/n = 2/1 NTM can be completely stabilized with the misalignment of the ECCD location less than about half of the full island width, and that the m/n = 2/1 NTM is destabilized with the misalignment comparable to the full island width. Time-dependent, self-consistent simulation of magnetic island evolution using the TOPICS code has shown that the stabilization and destabilization of an m/n = 2/1 NTM are well reproduced with the same set of coefficients of the modified Rutherford equation. The TOPICS simulation has also clarified that EC wave power required for complete stabilization can be significantly reduced by narrowing the ECCD deposition width
Simulation of neoclassical tearing mode stabilization via minimum seeking method on ITER
Energy Technology Data Exchange (ETDEWEB)
Park, M. H.; Kim, K.; Na, D. H.; Byun, C. S.; Na, Y. S. [Seoul National Univ., Seoul (Korea, Republic of); Kim, M. [FNC Technology Co. Ltd, Yongin (Korea, Republic of)
2016-10-15
Neoclassical tearing modes (NTMs) are well known resistive magnetohydrodynamic (MHD) instabilities. These instabilities are sustained by a helically perturbed bootstrap current. NTMs produce magnetic islands in tokamak plasmas that can degrade confinement and lead to plasma disruption. Because of this, the stabilization of NTMs is one of the key issues for tokamaks that achieve high fusion performance such as ITER. Compensating for the lack of bootstrap current by an Electron Cyclotron Current Drive (ECCD) has been proved experimentally as an effective method to stabilize NTMs. In order to stabilize NTMs, it is important to reduce misalignment. So that even ECCD can destabilize the NTMs when misalignment is large. Feedback control method that does not fully require delicate and accurate real-time measurements and calculations, such as equilibrium reconstruction and EC ray-tracing, has also been proposed. One of the feedback control methods is minimum seeking method. This control method minimizes the island width by tuning the misalignment, assuming that the magnetic island width is a function of the misalignment. As a robust and simple method of controlling NTM, minimum 'island width growth rate' seeking control is purposed and compared with performance of minimum ' island width' seeking control. At the integrated numerical system, simulations of the NTM suppression are performed with two types of minimum seeking controllers; one is a FDM based minimum seeking controller and the other is a sinusoidal perturbation based minimum seeking method. The full suppression is achieved both types of controller. The controllers adjust poloidal angle of EC beam and reduce misalignment to zero. The sinusoidal perturbation based minimum seeking control need to modify the adaptive gain.
A Molecular–Structure Hypothesis
Directory of Open Access Journals (Sweden)
Jan C. A. Boeyens
2010-11-01
Full Text Available The self-similar symmetry that occurs between atomic nuclei, biological growth structures, the solar system, globular clusters and spiral galaxies suggests that a similar pattern should characterize atomic and molecular structures. This possibility is explored in terms of the current molecular structure-hypothesis and its extension into four-dimensional space-time. It is concluded that a quantum molecule only has structure in four dimensions and that classical (Newtonian structure, which occurs in three dimensions, cannot be simulated by quantum-chemical computation.
Antiaging therapy: a prospective hypothesis
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Shahidi Bonjar MR
2015-01-01
Full Text Available Mohammad Rashid Shahidi Bonjar,1 Leyla Shahidi Bonjar2 1School of Dentistry, Kerman University of Medical Sciences, Kerman Iran; 2Department of Pharmacology, College of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran Abstract: This hypothesis proposes a new prospective approach to slow the aging process in older humans. The hypothesis could lead to developing new treatments for age-related illnesses and help humans to live longer. This hypothesis has no previous documentation in scientific media and has no protocol. Scientists have presented evidence that systemic aging is influenced by peculiar molecules in the blood. Researchers at Albert Einstein College of Medicine, New York, and Harvard University in Cambridge discovered elevated titer of aging-related molecules (ARMs in blood, which trigger cascade of aging process in mice; they also indicated that the process can be reduced or even reversed. By inhibiting the production of ARMs, they could reduce age-related cognitive and physical declines. The present hypothesis offers a new approach to translate these findings into medical treatment: extracorporeal adjustment of ARMs would lead to slower rates of aging. A prospective “antiaging blood filtration column” (AABFC is a nanotechnological device that would fulfill the central role in this approach. An AABFC would set a near-youth homeostatic titer of ARMs in the blood. In this regard, the AABFC immobilizes ARMs from the blood while blood passes through the column. The AABFC harbors antibodies against ARMs. ARM antibodies would be conjugated irreversibly to ARMs on contact surfaces of the reaction platforms inside the AABFC till near-youth homeostasis is attained. The treatment is performed with the aid of a blood-circulating pump. Similar to a renal dialysis machine, blood would circulate from the body to the AABFC and from there back to the body in a closed circuit until ARMs were sufficiently depleted from the blood. The
Maximizing ROI (return on information)
Energy Technology Data Exchange (ETDEWEB)
McDonald, B.
2000-05-01
The role and importance of managing information are discussed, underscoring the importance by quoting from the report of the International Data Corporation, according to which Fortune 500 companies lost $ 12 billion in 1999 due to inefficiencies resulting from intellectual re-work, substandard performance , and inability to find knowledge resources. The report predicts that this figure will rise to $ 31.5 billion by 2003. Key impediments to implementing knowledge management systems are identified as : the cost and human resources requirement of deployment; inflexibility of historical systems to adapt to change; and the difficulty of achieving corporate acceptance of inflexible software products that require changes in 'normal' ways of doing business. The author recommends the use of model, document and rule-independent systems with a document centered interface (DCI), employing rapid application development (RAD) and object technologies and visual model development, which eliminate these problems, making it possible for companies to maximize their return on information (ROI), and achieve substantial savings in implementation costs.
Maximizing the optical network capacity.
Bayvel, Polina; Maher, Robert; Xu, Tianhua; Liga, Gabriele; Shevchenko, Nikita A; Lavery, Domaniç; Alvarado, Alex; Killey, Robert I
2016-03-06
Most of the digital data transmitted are carried by optical fibres, forming the great part of the national and international communication infrastructure. The information-carrying capacity of these networks has increased vastly over the past decades through the introduction of wavelength division multiplexing, advanced modulation formats, digital signal processing and improved optical fibre and amplifier technology. These developments sparked the communication revolution and the growth of the Internet, and have created an illusion of infinite capacity being available. But as the volume of data continues to increase, is there a limit to the capacity of an optical fibre communication channel? The optical fibre channel is nonlinear, and the intensity-dependent Kerr nonlinearity limit has been suggested as a fundamental limit to optical fibre capacity. Current research is focused on whether this is the case, and on linear and nonlinear techniques, both optical and electronic, to understand, unlock and maximize the capacity of optical communications in the nonlinear regime. This paper describes some of them and discusses future prospects for success in the quest for capacity. © 2016 The Authors.
Directory of Open Access Journals (Sweden)
Anna Horodecka
2015-11-01
Full Text Available The economics depends on the concept of human nature very strongly. The concepts of human nature can be understood as a set of assumptions made about the individual (on different levels: behavior, motives, meaning and his interactions with other people, with groups and diverse institutions. It corresponds with the image of world people have. The concept of human nature together with an image of the world builds the basis of thinking about the economics and about such fundamental element of it as its goal. Therefore if those images of men change, the way of thinking about economics and their elements adjust to those changes as well. The goal of the paper is to present the impact of these alterations of image of man on the economics. This impact will be illustrated on the example of the evolutionary economics, which is contrasted with the orthodox concept of human nature persisting in the neoclassical economics – homo economicus. The method applied to this research is, among others, a content analysis of the most important texts developed within neoclassical and evolutionary economics. To reach this goal, the following steps will be conducted: firstly, the concepts of human nature will be defined in regards of their particularity depending on the discipline by which they are defined; secondly, the main differences between concepts of human nature in neoclassical and evolutionary economics will be analyzed, and thirdly the differences in understanding of the goal and field between those two schools will be explained as resulting from the diverse concepts of human nature. The analysis proved that the main differences in those economic schools might be explained by the changed assumptions about the human nature and the image of the world.
Is PMI the Hypothesis or the Null Hypothesis?
Tarone, Aaron M; Sanford, Michelle R
2017-09-01
Over the past several decades, there have been several strident exchanges regarding whether forensic entomologists estimate the postmortem interval (PMI), minimum PMI, or something else. During that time, there has been a proliferation of terminology reflecting this concern regarding "what we do." This has been a frustrating conversation for some in the community because much of this debate appears to be centered on what assumptions are acknowledged directly and which are embedded within a list of assumptions (or ignored altogether) in the literature and in case reports. An additional component of the conversation centers on a concern that moving away from the use of certain terminology like PMI acknowledges limitations and problems that would make the application of entomology appear less useful in court-a problem for lawyers, but one that should not be problematic for scientists in the forensic entomology community, as uncertainty is part of science that should and can be presented effectively in the courtroom (e.g., population genetic concepts in forensics). Unfortunately, a consequence of the way this conversation is conducted is that even as all involved in the debate acknowledge the concerns of their colleagues, parties continue to talk past one another advocating their preferred terminology. Progress will not be made until the community recognizes that all of the terms under consideration take the form of null hypothesis statements and that thinking about "what we do" as a null hypothesis has useful legal and scientific ramifications that transcend arguments over the usage of preferred terminology. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
The Stoichiometric Divisome: A Hypothesis
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Waldemar eVollmer
2015-05-01
Full Text Available Dividing Escherichia coli cells simultaneously constrict the inner membrane, peptidoglycan layer and outer membrane to synthesize the new poles of the daughter cells. For this, more than 30 proteins localize to mid-cell where they form a large, ring-like assembly, the divisome, facilitating division. Although the precise function of most divisome proteins is unknown, it became apparent in recent years that dynamic protein-protein interactions are essential for divisome assembly and function. However, little is known about the nature of the interactions involved and the stoichiometry of the proteins within the divisome. A recent study (Li et al., 2014 used ribosome profiling to measure the absolute protein synthesis rates in E. coli. Interestingly, they observed that most proteins which participate in known multiprotein complexes are synthesized proportional to their stoichiometry. Based on this principle we present a hypothesis for the stoichiometry of the core of the divisome, taking into account known protein-protein interactions. From this hypothesis we infer a possible mechanism for PG synthesis during division.
Satake, S; Park, J-K; Sugama, H; Kanno, R
2011-07-29
Neoclassical toroidal viscosities (NTVs) in tokamaks are investigated using a δf Monte Carlo simulation, and are successfully verified with a combined analytic theory over a wide range of collisionality. A Monte Carlo simulation has been required in the study of NTV since the complexities in guiding-center orbits of particles and their collisions cannot be fully investigated by any means of analytic theories alone. Results yielded the details of the complex NTV dependency on particle precessions and collisions, which were predicted roughly in a combined analytic theory. Both numerical and analytic methods can be utilized and extended based on these successful verifications.
Directory of Open Access Journals (Sweden)
Yurii Klapkiv
2017-08-01
Full Text Available The article explores the issues related to the institutional and financial infrastructure based on the scientific achievements of the neoclassical economy. The specific features of the concept of "institutionalization" are substantiated. The initial interpretation of the interpretation of institutions is revealed. Conceptual approaches to the study of the concept of “institutionalization” and “institute” in the insurance services market are defined. The attention to the galaxy values provided by the notion of an institution or organization. Key words: institutionalization, institute, organization, market of insurance services, insurance culture.
International Nuclear Information System (INIS)
Katanuma, I.; Kiwamoto, Y.; Adachi, S.; Inutake, M.; Ishii, K.; Yatsu, K.; Sawada, K.; Miyoshi, S.
1987-05-01
Calculations are made for neoclassical resonant-plateau transports in the geometry of the effectively axisymmetrized tandem mirror GAMMA 10 magnetic field, which has minimum B inbord anchors inside the axisymmetric plug/barrier mirror cells. Azimuthal drifts at the local non-axisymmetric regions are included. The radial potential profile is determined by solving selfconsistently the charge neutrality equation. A finite resistance connecting end plate to machine ground provides appropriate boundary conditions on the radial electrostatic potential distribution so that it can be determined uniquely. The calculation is consistent with experimental results of GAMMA 10. (author)
International Nuclear Information System (INIS)
Prater, R.; La Haye, R. J.; Lin-Liu, Y. R.; Lohr, J.; Perkins, F. W.; Bernabei, S.; Wong, K.-L.; Harvey, R. W.
1999-01-01
Neoclassical tearing modes are found to limit the achievable beta in many high performance discharges in DIII-D. Electron cyclotron current drive within the magnetic islands formed as the tearing mode grows has been proposed as a means of stabilizing these modes or reducing their amplitude, thereby increasing the beta limit by a factor around 1.5. Some experimental success has been obtained previously on Asdex-U. Here we examine the parameter range in DIII-D in which this effect can best be studied
International Nuclear Information System (INIS)
Taniguchi, Satoshi; Yamazaki, Kozo; Oishi, Tetsutarou; Arimoto, Hideki; Shoji, Tatsuo
2010-01-01
On tokamak plasmas like ITER, it is necessary to stabilize neoclassical tearing mode (NTM) because the NTM reduces plasma temperature and fusion power output. For the analysis of stabilizing NTM in fusion plasmas, the electron cyclotron current drive (ECCD) and the non-resonant external helical field (NRHF) application are simulated using the 1.5-dimensional equilibrium/transport simulation code (TOTAL code). The 3/2 NTM is stabilized by only external helical field, but the 2/1 mode is not stabilized by only external helical field in the present model. The stabilization time becomes shorter by the combination of ECCD and NRHF than that by ECCD alone. (author)
International Nuclear Information System (INIS)
Lazaros, Avrilios; Maraschek, Marc; Zohm, Hartmut
2007-01-01
An analytic model for the advantage of the early application of electron cyclotron current drive (ECCD) in the suppression of neoclassical tearing modes (NTMs) is presented. The improved performance of early ECCD is attributed to the second (smaller) saturation island width, which appears for sufficiently small (relative to the ECCD deposition width) critical island widths, in the strongly nonlinear growth rate profile. The operational range for the advantage of early ECCD is obtained, and it is shown that it is favored by broad deposition profiles. The preliminary experimental results in ASDEX Upgrade [H. Zohm et al., Nucl. Fusion 41, 197 (2001)] are consistent with the present model
An omnibus test for the global null hypothesis.
Futschik, Andreas; Taus, Thomas; Zehetmayer, Sonja
2018-01-01
Global hypothesis tests are a useful tool in the context of clinical trials, genetic studies, or meta-analyses, when researchers are not interested in testing individual hypotheses, but in testing whether none of the hypotheses is false. There are several possibilities how to test the global null hypothesis when the individual null hypotheses are independent. If it is assumed that many of the individual null hypotheses are false, combination tests have been recommended to maximize power. If, however, it is assumed that only one or a few null hypotheses are false, global tests based on individual test statistics are more powerful (e.g. Bonferroni or Simes test). However, usually there is no a priori knowledge on the number of false individual null hypotheses. We therefore propose an omnibus test based on cumulative sums of the transformed p-values. We show that this test yields an impressive overall performance. The proposed method is implemented in an R-package called omnibus.
International Nuclear Information System (INIS)
Nemov, V V; Kalyuzhnyj, V N; Kasilov, S V; Drevlak, M; Nuehrenberg, J; Kernbichler, W; Reiman, A; Monticello, D
2004-01-01
For the magnetic field of the Wendelstein 7-X (W7-X) standard high-mirror configuration, computed by the PIES code, taking into account real coil geometry, neoclassical transport and bootstrap current are analysed in the 1/upsilon regime using methods based on the integration along magnetic field lines in a given magnetic field. The zero beta and (beta) = 1% cases are studied. The results are compared to the corresponding results for the vacuum magnetic field directly produced by modular coils. A significant advantage of W7-X over a conventional stellarator resulting from reduced neoclassical transport and from reduced bootstrap current follows from the computations although the neoclassical transport is somewhat larger than that previously obtained for the ideal W7-X model configuration
AUC-Maximizing Ensembles through Metalearning.
LeDell, Erin; van der Laan, Mark J; Petersen, Maya
2016-05-01
Area Under the ROC Curve (AUC) is often used to measure the performance of an estimator in binary classification problems. An AUC-maximizing classifier can have significant advantages in cases where ranking correctness is valued or if the outcome is rare. In a Super Learner ensemble, maximization of the AUC can be achieved by the use of an AUC-maximining metalearning algorithm. We discuss an implementation of an AUC-maximization technique that is formulated as a nonlinear optimization problem. We also evaluate the effectiveness of a large number of different nonlinear optimization algorithms to maximize the cross-validated AUC of the ensemble fit. The results provide evidence that AUC-maximizing metalearners can, and often do, out-perform non-AUC-maximizing metalearning methods, with respect to ensemble AUC. The results also demonstrate that as the level of imbalance in the training data increases, the Super Learner ensemble outperforms the top base algorithm by a larger degree.
On maximal massive 3D supergravity
Bergshoeff , Eric A; Hohm , Olaf; Rosseel , Jan; Townsend , Paul K
2010-01-01
ABSTRACT We construct, at the linearized level, the three-dimensional (3D) N = 4 supersymmetric " general massive supergravity " and the maximally supersymmetric N = 8 " new massive supergravity ". We also construct the maximally supersymmetric linearized N = 7 topologically massive supergravity, although we expect N = 6 to be maximal at the non-linear level. (Bergshoeff, Eric A) (Hohm, Olaf) (Rosseel, Jan) P.K.Townsend@da...
Inclusive Fitness Maximization:An Axiomatic Approach
Okasha, Samir; Weymark, John; Bossert, Walter
2014-01-01
Kin selection theorists argue that evolution in social contexts will lead organisms to behave as if maximizing their inclusive, as opposed to personal, fitness. The inclusive fitness concept allows biologists to treat organisms as akin to rational agents seeking to maximize a utility function. Here we develop this idea and place it on a firm footing by employing a standard decision-theoretic methodology. We show how the principle of inclusive fitness maximization and a related principle of qu...
Hurst, Laurence D.; Ghanbarian, Avazeh T.; Forrest, Alistair R. R.; Huminiecki, Lukasz
2015-01-01
to the ancestral rate (per promoter) prior to the X chromosome formation, then the X is not a tolerable environment for genes with very high maximal net levels of expression, owing to transcriptional traffic jams. We test this hypothesis using The Encyclopedia
Activity versus outcome maximization in time management.
Malkoc, Selin A; Tonietto, Gabriela N
2018-04-30
Feeling time-pressed has become ubiquitous. Time management strategies have emerged to help individuals fit in more of their desired and necessary activities. We provide a review of these strategies. In doing so, we distinguish between two, often competing, motives people have in managing their time: activity maximization and outcome maximization. The emerging literature points to an important dilemma: a given strategy that maximizes the number of activities might be detrimental to outcome maximization. We discuss such factors that might hinder performance in work tasks and enjoyment in leisure tasks. Finally, we provide theoretically grounded recommendations that can help balance these two important goals in time management. Published by Elsevier Ltd.
On the maximal superalgebras of supersymmetric backgrounds
International Nuclear Information System (INIS)
Figueroa-O'Farrill, Jose; Hackett-Jones, Emily; Moutsopoulos, George; Simon, Joan
2009-01-01
In this paper we give a precise definition of the notion of a maximal superalgebra of certain types of supersymmetric supergravity backgrounds, including the Freund-Rubin backgrounds, and propose a geometric construction extending the well-known construction of its Killing superalgebra. We determine the structure of maximal Lie superalgebras and show that there is a finite number of isomorphism classes, all related via contractions from an orthosymplectic Lie superalgebra. We use the structure theory to show that maximally supersymmetric waves do not possess such a maximal superalgebra, but that the maximally supersymmetric Freund-Rubin backgrounds do. We perform the explicit geometric construction of the maximal superalgebra of AdS 4 X S 7 and find that it is isomorphic to osp(1|32). We propose an algebraic construction of the maximal superalgebra of any background asymptotic to AdS 4 X S 7 and we test this proposal by computing the maximal superalgebra of the M2-brane in its two maximally supersymmetric limits, finding agreement.
Task-oriented maximally entangled states
International Nuclear Information System (INIS)
Agrawal, Pankaj; Pradhan, B
2010-01-01
We introduce the notion of a task-oriented maximally entangled state (TMES). This notion depends on the task for which a quantum state is used as the resource. TMESs are the states that can be used to carry out the task maximally. This concept may be more useful than that of a general maximally entangled state in the case of a multipartite system. We illustrate this idea by giving an operational definition of maximally entangled states on the basis of communication tasks of teleportation and superdense coding. We also give examples and a procedure to obtain such TMESs for n-qubit systems.
International Nuclear Information System (INIS)
Mikhailovskii, A.B.; Smolyakov, A.I.; Kovalishen, E.A.; Shirokov, M.S.; Tsypin, V.S.; Galvao, R.M.O.
2006-01-01
Generation of zonal flows by primary waves that are more complex than those considered in the standard drift-wave model is studied. The effects of parallel ion velocity and ion perturbed temperature and the part of the nonlinear mode interaction proportional to the ion pressure are taken into account. This generalization of the standard model allows the analysis of generation of zonal flows by a rather wide variety of primary modes, including ion temperature gradients, ion sound, electron drift, and drift-sound modes. All the listed effects, which are present in the slab geometry model, are complemented by effects of neoclassical viscosity inherent to toroidal geometry. We show that the electrostatic potential of secondary small-scale modes is expressed in terms of a nonlinear shift of the mode frequency and interpret this shift in terms of the perpendicular and parallel Doppler, nonlinear Kelvin-Helmholtz (KH), and nonlinear ion-pressure-gradient effects. A basic assumption of our model is that the primary modes form a nondispersive monochromatic wave packet. The analysis of zonal-flow generation is performed following an approach similar to that of convective-cell theory. Neoclassical zonal-flow instabilities are separated into fast and slow ones, and these are divided into two varieties. The first of them is independent of the nonlinear KH effect, while the second one is sensitive to it
International Nuclear Information System (INIS)
Bruma, C.; Cuperman, S.; Komoshvili, K.
1999-01-01
Some basic aspects of wave-plasma interaction of interest for tight aspect ratio spherical tokamaks are investigated theoretically. The following scenario is considered: A. Fast magnetosonic waves are launched by an external antenna into a simulated spherical Tokamak plasma; these waves are converted to Alfven waves at points (layer) satisfying the Alfven resonance condition. B. The simulated spherical tokamaks-plasma has a circular cross-section and toroidicity effects are simulated by Grad-Shafranov type, radially dependent axial magnetic field and its shear. (J. Actual equilibrium profiles (magnetic field, pressure and current) observed in the low field side (LFS) of spherical tokamaks (viz., START at Culham, UK) are used. D. The study is based on the numerical solution of the full e.m. wave equation which includes a quite general resistive MHD dielectric tensor, with consideration of equilibrium current and neoclassical effects. Two kinds of results will be presented: I. Proofs validating the computational algorithm used and including convergence and energy conservation. II. Exact quantitative results concerning (i) the structure and space dependence of the mode-converted Alfven waves and (ii) the basic features of the deposited p over . The dependence of the results on the launched wave characteristics (wave numbers, frequency and intensity) as well as on those of the equilibrium plasma (equilibrium current, neoclassical resistivity and electron inertia) will be discussed
Memory in astrocytes: a hypothesis
Directory of Open Access Journals (Sweden)
Caudle Robert M
2006-01-01
Full Text Available Abstract Background Recent work has indicated an increasingly complex role for astrocytes in the central nervous system. Astrocytes are now known to exchange information with neurons at synaptic junctions and to alter the information processing capabilities of the neurons. As an extension of this trend a hypothesis was proposed that astrocytes function to store information. To explore this idea the ion channels in biological membranes were compared to models known as cellular automata. These comparisons were made to test the hypothesis that ion channels in the membranes of astrocytes form a dynamic information storage device. Results Two dimensional cellular automata were found to behave similarly to ion channels in a membrane when they function at the boundary between order and chaos. The length of time information is stored in this class of cellular automata is exponentially related to the number of units. Therefore the length of time biological ion channels store information was plotted versus the estimated number of ion channels in the tissue. This analysis indicates that there is an exponential relationship between memory and the number of ion channels. Extrapolation of this relationship to the estimated number of ion channels in the astrocytes of a human brain indicates that memory can be stored in this system for an entire life span. Interestingly, this information is not affixed to any physical structure, but is stored as an organization of the activity of the ion channels. Further analysis of two dimensional cellular automata also demonstrates that these systems have both associative and temporal memory capabilities. Conclusion It is concluded that astrocytes may serve as a dynamic information sink for neurons. The memory in the astrocytes is stored by organizing the activity of ion channels and is not associated with a physical location such as a synapse. In order for this form of memory to be of significant duration it is necessary
Maximal hypersurfaces and foliations of constant mean curvature in general relativity
International Nuclear Information System (INIS)
Marsden, J.E.; Tipler, F.J.; Texas Univ., Austin
1980-01-01
We prove theorems on existence, uniqueness and smoothness of maximal and constant mean curvature compact spacelike hypersurfaces in globally hyperbolic spacetimes. The uniqueness theorem for maximal hypersurfaces of Brill and Flaherty, which assumed matter everywhere, is extended to specetimes that are vacuum and non-flat or that satisfy a generic-type condition. In this connection we show that under general hypotheses, a spatially closed universe with a maximal hypersurface must be Wheeler universe; i.e. be closed in time as well. The existence of Lipschitz achronal maximal volume hypersurfaces under the hypothesis that candidate hypersurfaces are bounded away from the singularity is proved. This hypothesis is shown to be valid in two cases of interest: when the singularities are of strong curvature type, and when the singularity is a single ideal point. Some properties of these maximal volume hypersurfaces and difficulties with Avez' original arguments are discussed. The difficulties involve the possibility that the maximal volume hypersurface can be null on certain portions; we present an incomplete argument which suggests that these hypersurfaces are always smooth, but prove that an a priori bound on the second fundamental form does imply smoothness. An extension of the perturbation theorem of Choquet-Bruhat, Fischer and Marsden is given and conditions under which local foliantions by constant mean curvature hypersurfaces can be extended to global ones is obtained. (orig.)
Robust and distributed hypothesis testing
Gül, Gökhan
2017-01-01
This book generalizes and extends the available theory in robust and decentralized hypothesis testing. In particular, it presents a robust test for modeling errors which is independent from the assumptions that a sufficiently large number of samples is available, and that the distance is the KL-divergence. Here, the distance can be chosen from a much general model, which includes the KL-divergence as a very special case. This is then extended by various means. A minimax robust test that is robust against both outliers as well as modeling errors is presented. Minimax robustness properties of the given tests are also explicitly proven for fixed sample size and sequential probability ratio tests. The theory of robust detection is extended to robust estimation and the theory of robust distributed detection is extended to classes of distributions, which are not necessarily stochastically bounded. It is shown that the quantization functions for the decision rules can also be chosen as non-monotone. Finally, the boo...
The venom optimization hypothesis revisited.
Morgenstern, David; King, Glenn F
2013-03-01
Animal venoms are complex chemical mixtures that typically contain hundreds of proteins and non-proteinaceous compounds, resulting in a potent weapon for prey immobilization and predator deterrence. However, because venoms are protein-rich, they come with a high metabolic price tag. The metabolic cost of venom is sufficiently high to result in secondary loss of venom whenever its use becomes non-essential to survival of the animal. The high metabolic cost of venom leads to the prediction that venomous animals may have evolved strategies for minimizing venom expenditure. Indeed, various behaviors have been identified that appear consistent with frugality of venom use. This has led to formulation of the "venom optimization hypothesis" (Wigger et al. (2002) Toxicon 40, 749-752), also known as "venom metering", which postulates that venom is metabolically expensive and therefore used frugally through behavioral control. Here, we review the available data concerning economy of venom use by animals with either ancient or more recently evolved venom systems. We conclude that the convergent nature of the evidence in multiple taxa strongly suggests the existence of evolutionary pressures favoring frugal use of venom. However, there remains an unresolved dichotomy between this economy of venom use and the lavish biochemical complexity of venom, which includes a high degree of functional redundancy. We discuss the evidence for biochemical optimization of venom as a means of resolving this conundrum. Copyright © 2012 Elsevier Ltd. All rights reserved.
Alien abduction: a medical hypothesis.
Forrest, David V
2008-01-01
In response to a new psychological study of persons who believe they have been abducted by space aliens that found that sleep paralysis, a history of being hypnotized, and preoccupation with the paranormal and extraterrestrial were predisposing experiences, I noted that many of the frequently reported particulars of the abduction experience bear more than a passing resemblance to medical-surgical procedures and propose that experience with these may also be contributory. There is the altered state of consciousness, uniformly colored figures with prominent eyes, in a high-tech room under a round bright saucerlike object; there is nakedness, pain and a loss of control while the body's boundaries are being probed; and yet the figures are thought benevolent. No medical-surgical history was apparently taken in the above mentioned study, but psychological laboratory work evaluated false memory formation. I discuss problems in assessing intraoperative awareness and ways in which the medical hypothesis could be elaborated and tested. If physicians are causing this syndrome in a percentage of patients, we should know about it; and persons who feel they have been abducted should be encouraged to inform their surgeons and anesthesiologists without challenging their beliefs.
The oxidative hypothesis of senescence
Directory of Open Access Journals (Sweden)
Gilca M
2007-01-01
Full Text Available The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g., those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc. This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal β -oxidation and respiratory burst of phagocytic cells, antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol, alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.
Bongers, F.; Poorter, L.; Hawthorne, W.D.; Sheil, D.
2009-01-01
The intermediate disturbance hypothesis (IDH) predicts local species diversity to be maximal at an intermediate level of disturbance. Developed to explain species maintenance and diversity patterns in species-rich ecosystems such as tropical forests, tests of IDH in tropical forest remain scarce,
Drag reduction by air release promotes fast ascent in jumping emperor penguins—a novel hypothesis
DEFF Research Database (Denmark)
Davenport, J.; Hughes, R.N.; Shorten, M
2011-01-01
lubrication’) has been used by engineers to speed movement of vehicles (ships, torpedoes) through sea water. Analysis of published and unpublished underwater film leads us to present a hypothesis that free-ranging emperor penguins employ air lubrication in achieving high, probably maximal, underwater speeds...
Maximally Entangled Multipartite States: A Brief Survey
International Nuclear Information System (INIS)
Enríquez, M; Wintrowicz, I; Życzkowski, K
2016-01-01
The problem of identifying maximally entangled quantum states of a composite quantum systems is analyzed. We review some states of multipartite systems distinguished with respect to certain measures of quantum entanglement. Numerical results obtained for 4-qubit pure states illustrate the fact that the notion of maximally entangled state depends on the measure used. (paper)
Utility maximization and mode of payment
Koning, R.H.; Ridder, G.; Heijmans, R.D.H.; Pollock, D.S.G.; Satorra, A.
2000-01-01
The implications of stochastic utility maximization in a model of choice of payment are examined. Three types of compatibility with utility maximization are distinguished: global compatibility, local compatibility on an interval, and local compatibility on a finite set of points. Keywords:
Corporate Social Responsibility and Profit Maximizing Behaviour
Becchetti, Leonardo; Giallonardo, Luisa; Tessitore, Maria Elisabetta
2005-01-01
We examine the behavior of a profit maximizing monopolist in a horizontal differentiation model in which consumers differ in their degree of social responsibility (SR) and consumers SR is dynamically influenced by habit persistence. The model outlines parametric conditions under which (consumer driven) corporate social responsibility is an optimal choice compatible with profit maximizing behavior.
Inclusive fitness maximization: An axiomatic approach.
Okasha, Samir; Weymark, John A; Bossert, Walter
2014-06-07
Kin selection theorists argue that evolution in social contexts will lead organisms to behave as if maximizing their inclusive, as opposed to personal, fitness. The inclusive fitness concept allows biologists to treat organisms as akin to rational agents seeking to maximize a utility function. Here we develop this idea and place it on a firm footing by employing a standard decision-theoretic methodology. We show how the principle of inclusive fitness maximization and a related principle of quasi-inclusive fitness maximization can be derived from axioms on an individual׳s 'as if preferences' (binary choices) for the case in which phenotypic effects are additive. Our results help integrate evolutionary theory and rational choice theory, help draw out the behavioural implications of inclusive fitness maximization, and point to a possible way in which evolution could lead organisms to implement it. Copyright © 2014 Elsevier Ltd. All rights reserved.
Maximal Entanglement in High Energy Physics
Directory of Open Access Journals (Sweden)
Alba Cervera-Lierta, José I. Latorre, Juan Rojo, Luca Rottoli
2017-11-01
Full Text Available We analyze how maximal entanglement is generated at the fundamental level in QED by studying correlations between helicity states in tree-level scattering processes at high energy. We demonstrate that two mechanisms for the generation of maximal entanglement are at work: i $s$-channel processes where the virtual photon carries equal overlaps of the helicities of the final state particles, and ii the indistinguishable superposition between $t$- and $u$-channels. We then study whether requiring maximal entanglement constrains the coupling structure of QED and the weak interactions. In the case of photon-electron interactions unconstrained by gauge symmetry, we show how this requirement allows reproducing QED. For $Z$-mediated weak scattering, the maximal entanglement principle leads to non-trivial predictions for the value of the weak mixing angle $\\theta_W$. Our results are a first step towards understanding the connections between maximal entanglement and the fundamental symmetries of high-energy physics.
Frassinetti, L.; Sun, Y.; Fridström, R.; Menmuir, S.; Olofsson, K. E. J.; Brunsell, P. R.; Khan, M. W. M.; Liang, Y.; Drake, J. R.
2015-09-01
The non-resonant magnetic perturbation (MP) braking is studied in the EXTRAP T2R reversed-field pinch (RFP) and the experimental braking torque is compared with the torque expected by the neoclassical toroidal viscosity (NTV) theory. The EXTRAP T2R active coils can apply magnetic perturbations with a single harmonic, either resonant or non-resonant. The non-resonant MP produces velocity braking with an experimental torque that affects a large part of the core region. The experimental torque is clearly related to the plasma displacement, consistent with a quadratic dependence as expected by the NTV theory. The work show a good qualitative agreement between the experimental torque in a RFP machine and NTV torque concerning both the torque density radial profile and the dependence on the non-resonant MP harmonic.
Energy Technology Data Exchange (ETDEWEB)
Seo, Janghoon; Choe, W. [Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Chang, C. S.; Ku, S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Kwon, J. M. [National Fusion Research institute, Daejeon 305-806 (Korea, Republic of); Müller, Stefan H. [Max Planck Institute for Plasma Physics, Garching 85748 (Germany); Center for Energy Research, University of California San Diego, La Jolla, California 92093 (United States)
2014-09-15
Fluid Reynolds stress from turbulence has usually been considered to be responsible for the anomalous toroidal momentum transport in tokamak plasma. Experiment by Müller et al. [Phys. Rev. Lett. 106, 115001 (2011)], however, reported that neither the observed edge rotation profile nor the inward momentum transport phenomenon at the edge region of an H-mode plasma could be explained by the fluid Reynolds stress measured with reciprocating Langmuir-probe. The full-function gyrokinetic code XGC1 is used to explain, for the first time, Müller et al.'s experimental observations. It is discovered that, unlike in the plasma core, the fluid Reynolds stress from turbulence is not sufficient for momentum transport physics in plasma edge. The “turbulent neoclassical” physics arising from the interaction between kinetic neoclassical orbit dynamics and plasma turbulence is key in the tokamak edge region across the plasma pedestal into core.
Crombé, K; Andrew, Y; Brix, M; Giroud, C; Hacquin, S; Hawkes, N C; Murari, A; Nave, M F F; Ongena, J; Parail, V; Van Oost, G; Voitsekhovitch, I; Zastrow, K-D
2005-10-07
Results from the first measurements of a core plasma poloidal rotation velocity (upsilontheta) across internal transport barriers (ITB) on JET are presented. The spatial and temporal evolution of the ITB can be followed along with the upsilontheta radial profiles, providing a very clear link between the location of the steepest region of the ion temperature gradient and localized spin-up of upsilontheta. The upsilontheta measurements are an order of magnitude higher than the neoclassical predictions for thermal particles in the ITB region, contrary to the close agreement found between the determined and predicted particle and heat transport coefficients [K.-D. Zastrow, Plasma Phys. Controlled Fusion 46, B255 (2004)]. These results have significant implications for the understanding of transport barrier dynamics due to their large impact on the measured radial electric field profile.
International Nuclear Information System (INIS)
Satake, Shinsuke; Okamoto, Masao; Nakajima, Noriyoshi; Takamaru, Hisanori
2005-11-01
A neoclassical transport simulation code (FORTEC-3D) applicable to three-dimensional configurations has been developed using High Performance Fortran (HPF). Adoption of computing techniques for parallelization and a hybrid simulation model to the δf Monte-Carlo method transport simulation, including non-local transport effects in three-dimensional configurations, makes it possible to simulate the dynamism of global, non-local transport phenomena with a self-consistent radial electric field within a reasonable computation time. In this paper, development of the transport code using HPF is reported. Optimization techniques in order to achieve both high vectorization and parallelization efficiency, adoption of a parallel random number generator, and also benchmark results, are shown. (author)
Energy Technology Data Exchange (ETDEWEB)
Ku, S [Courant Institute of Mathematical Sciences, New York University (United States); Chang, C-S [Courant Institute of Mathematical Sciences, New York University (United States); Adams, M [Columbia University (United States); Cummings, J [California Institute of Technology (United States); Hinton, F [Hinton Associates (United States); Keyes, D [Columbia University (United States); Klasky, S [Oak Ridge National Laboratory (United States); Lee, W [Princeton Plasma Physics Laboratory (United States); Lin, Z [University of California at Irvine (United States); Parker, S [University of Colorado at Boulder (United States)
2006-09-15
A gyrokinetic neoclassical solution for a diverted tokamak edge plasma has been obtained for the first time using the massively parallel Jaguar XT3 computer at Oak Ridge National Laboratory. The solutions show similar characteristics to the experimental observations: electric potential is positive in the scrape-off layer and negative in the H-mode layer, and the parallel rotation is positive in the scrape-off layer and at the inside boundary of the H-mode layer. However, the solution also makes a new physical discovery that there is a strong ExB convective flow in the scrape-off plasma. A general introduction to the edge simulation problem is also presented.
Energy Technology Data Exchange (ETDEWEB)
O' Gorman, T.; Gibson, K. J.; Snape, J. A. [York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom); Naylor, G.; Huang, B.; McArdle, G. J.; Scannell, R.; Shibaev, S.; Thomas-Davies, N. [EURATOM/CCFE Fusion Association, Culham Science Centre, Oxfordshire OX14 3DB (United Kingdom)
2012-10-15
A real-time system has been developed to trigger both the MAST Thomson scattering (TS) system and the plasma control system on the phase and amplitude of neoclassical tearing modes (NTMs), extending the capabilities of the original system. This triggering system determines the phase and amplitude of a given NTM using magnetic coils at different toroidal locations. Real-time processing of the raw magnetic data occurs on a low cost field programmable gate array (FPGA) based unit which permits triggering of the TS lasers on specific amplitudes and phases of NTM evolution. The MAST plasma control system can receive a separate trigger from the FPGA unit that initiates a vertical shift of the MAST magnetic axis. Such shifts have fully removed m/n= 2/1 NTMs instabilities on a number of MAST discharges.
International Nuclear Information System (INIS)
Schweickardt, Gustavo Alejandro; Pistonesi, Hector
2008-01-01
The introduction of contestability conditions in the market of electricity distribution, following the dominant economic paradigm (Neoclassical or Marginalist) and solidary to the commercialization segment, it doesn't exhibit satisfactory solutions at the present time. This asseveration, of general character, have special incumbency for those countries of Latin America that, from regulatory schemes, try to define a deregulated market for certain kind of user (denominated eligible). A eligible user is characterized by to have demands equal or higher than a preset threshold value of electric power/ energy. In this work, considering the models implemented in the telecommunications networks, the problem of allocation of distribution costs, as the first step toward a contestable offer in the retail energy service, is discussed to establishing access prices in the distribution networks (non contestable markets). The analysis is focalized to definition of two market segments: one regulated and other competitive. Their methodological and instrumentation difficulties, are presented, concluding in the necessity of an alternative paradigm.
Real-time determination of magnetic island location for neoclassical tearing mode control in DIII-D
International Nuclear Information System (INIS)
Park, Y S; Welander, A S
2006-01-01
Accurate measurement of island location is crucial for efficient suppression of the neoclassical tearing mode by electron cyclotron current drive (ECCD). In the control system on DIII-D the contour of the resonant q-surface is measured in real time based on real-time magnetohydrodynamic reconstructions, EFITs, that include motional Stark effect measurements of pitch angle in the analysis. A new method for determination of the radial position of the q-surface using a 40 channel electron cyclotron emission radiometer has been developed. This method analyses localized temperature fluctuations caused by motion of the island and can be used by the plasma control system as a complementary measurement of the radial position of the q-surface contour for faster and more accurate alignment of the ECCD
Energy Technology Data Exchange (ETDEWEB)
Punjabi, A; Vahala, G [College of William and Mary, Williamsburg, VA (USA). Dept. of Physics
1983-12-01
The point model for the toroidal core plasma in the ELMO Bumpy Torus (with neoclassical non-resonant electrons) is examined in the light of catastrophe theory. Even though the point model equations do not constitute a gradient dynamic system, the equilibrium surfaces are similar to those of the canonical cusp catastrophe. The point model is then extended to incorporate ion cyclotron resonance heating. A detailed parametric study of the equilibria is presented. Further, the nonlinear time evolution of these equilibria is studied, and it is observed that the point model obeys the delay convention (and hence hysteresis) and shows catastrophes at the fold edges of the equilibrium surfaces. Tentative applications are made to experimental results.
Bipartite Bell Inequality and Maximal Violation
International Nuclear Information System (INIS)
Li Ming; Fei Shaoming; Li-Jost Xian-Qing
2011-01-01
We present new bell inequalities for arbitrary dimensional bipartite quantum systems. The maximal violation of the inequalities is computed. The Bell inequality is capable of detecting quantum entanglement of both pure and mixed quantum states more effectively. (general)
HEALTH INSURANCE: CONTRIBUTIONS AND REIMBURSEMENT MAXIMAL
HR Division
2000-01-01
Affected by both the salary adjustment index on 1.1.2000 and the evolution of the staff members and fellows population, the average reference salary, which is used as an index for fixed contributions and reimbursement maximal, has changed significantly. An adjustment of the amounts of the reimbursement maximal and the fixed contributions is therefore necessary, as from 1 January 2000.Reimbursement maximalThe revised reimbursement maximal will appear on the leaflet summarising the benefits for the year 2000, which will soon be available from the divisional secretariats and from the AUSTRIA office at CERN.Fixed contributionsThe fixed contributions, applicable to some categories of voluntarily insured persons, are set as follows (amounts in CHF for monthly contributions):voluntarily insured member of the personnel, with complete coverage:815,- (was 803,- in 1999)voluntarily insured member of the personnel, with reduced coverage:407,- (was 402,- in 1999)voluntarily insured no longer dependent child:326,- (was 321...
Maximal Inequalities for Dependent Random Variables
DEFF Research Database (Denmark)
Hoffmann-Jorgensen, Jorgen
2016-01-01
Maximal inequalities play a crucial role in many probabilistic limit theorem; for instance, the law of large numbers, the law of the iterated logarithm, the martingale limit theorem and the central limit theorem. Let X-1, X-2,... be random variables with partial sums S-k = X-1 + ... + X-k. Then a......Maximal inequalities play a crucial role in many probabilistic limit theorem; for instance, the law of large numbers, the law of the iterated logarithm, the martingale limit theorem and the central limit theorem. Let X-1, X-2,... be random variables with partial sums S-k = X-1 + ... + X......-k. Then a maximal inequality gives conditions ensuring that the maximal partial sum M-n = max(1) (...
Maximizing Function through Intelligent Robot Actuator Control
National Aeronautics and Space Administration — Maximizing Function through Intelligent Robot Actuator Control Successful missions to Mars and beyond will only be possible with the support of high-performance...
An ethical justification of profit maximization
DEFF Research Database (Denmark)
Koch, Carsten Allan
2010-01-01
In much of the literature on business ethics and corporate social responsibility, it is more or less taken for granted that attempts to maximize profits are inherently unethical. The purpose of this paper is to investigate whether an ethical argument can be given in support of profit maximizing...... behaviour. It is argued that some form of consequential ethics must be applied, and that both profit seeking and profit maximization can be defended from a rule-consequential point of view. It is noted, however, that the result does not apply unconditionally, but requires that certain form of profit (and...... utility) maximizing actions are ruled out, e.g., by behavioural norms or formal institutions....
A definition of maximal CP-violation
International Nuclear Information System (INIS)
Roos, M.
1985-01-01
The unitary matrix of quark flavour mixing is parametrized in a general way, permitting a mathematically natural definition of maximal CP violation. Present data turn out to violate this definition by 2-3 standard deviations. (orig.)
A cosmological problem for maximally symmetric supergravity
International Nuclear Information System (INIS)
German, G.; Ross, G.G.
1986-01-01
Under very general considerations it is shown that inflationary models of the universe based on maximally symmetric supergravity with flat potentials are unable to resolve the cosmological energy density (Polonyi) problem. (orig.)
Maximal supergravities and the E10 model
International Nuclear Information System (INIS)
Kleinschmidt, Axel; Nicolai, Hermann
2006-01-01
The maximal rank hyperbolic Kac-Moody algebra e 10 has been conjectured to play a prominent role in the unification of duality symmetries in string and M theory. We review some recent developments supporting this conjecture
Energy Technology Data Exchange (ETDEWEB)
Bruma, C.; Komoshvili, K. [Tel Aviv Univ. (Israel). School of Physics and Astronomy; Coll. of Judea and Samaria, Ariel (Israel); Cuperman, S. [Tel Aviv Univ. (Israel). School of Physics and Astronomy
2000-11-01
Some basic aspects of wave-plasma interaction of special interest for tight aspect ratio (spherical) tokamaks (ST's) are investigated numerically; these aspects include fast mode conversion and energy deposition. The study is based on the numerical solution of the full electro-magnetic (e.m.) wave equation which includes a quite general two-fluid, resistive MHD dielectric tensor, with consideration of equilibrium current and neoclassical effects. A generalized expression for the power absorption appropriate for the above scenario, with consideration of all the basic effects also present in the dielectric tensor-operator, was derived and used. The current-carrying ST-plasma has a circular cross-section and toroidicity effects are simulated by a Grad-Shafranov type, radially dependent axial magnetic field and its shear; however, the Shafranov shift is not considered. Actually, the equilibrium parameters and radial profiles (magnetic field, pressure and current) observed in the low field side (LFS) of spherical tokamaks (viz., START at Culham, UK) are used. Fast magnetosonic waves are launched from an external antenna into this simulated spherical tokamak plasma; these waves are converted to Alfven waves at points (layers) satisfying the Alfven resonance condition. Quantitative-results concerning (i) the structure and space dependence of the mode-converted Alfven waves and (ii) the basic features of the deposited power are presented. Their dependence on the equilibrium plasma current, neoclassical resistivity and electron inertia as well as on those of the antenna launched wave (wave numbers, frequency and current intensity) is systematically studied and discussed. (orig.)
International Nuclear Information System (INIS)
Bruma, C.; Komoshvili, K.; Cuperman, S.
2000-01-01
Some basic aspects of wave-plasma interaction of special interest for tight aspect ratio (spherical) tokamaks (ST's) are investigated numerically; these aspects include fast mode conversion and energy deposition. The study is based on the numerical solution of the full electro-magnetic (e.m.) wave equation which includes a quite general two-fluid, resistive MHD dielectric tensor, with consideration of equilibrium current and neoclassical effects. A generalized expression for the power absorption appropriate for the above scenario, with consideration of all the basic effects also present in the dielectric tensor-operator, was derived and used. The current-carrying ST-plasma has a circular cross-section and toroidicity effects are simulated by a Grad-Shafranov type, radially dependent axial magnetic field and its shear; however, the Shafranov shift is not considered. Actually, the equilibrium parameters and radial profiles (magnetic field, pressure and current) observed in the low field side (LFS) of spherical tokamaks (viz., START at Culham, UK) are used. Fast magnetosonic waves are launched from an external antenna into this simulated spherical tokamak plasma; these waves are converted to Alfven waves at points (layers) satisfying the Alfven resonance condition. Quantitative-results concerning (i) the structure and space dependence of the mode-converted Alfven waves and (ii) the basic features of the deposited power are presented. Their dependence on the equilibrium plasma current, neoclassical resistivity and electron inertia as well as on those of the antenna launched wave (wave numbers, frequency and current intensity) is systematically studied and discussed. (orig.)
Gaussian maximally multipartite-entangled states
Facchi, Paolo; Florio, Giuseppe; Lupo, Cosmo; Mancini, Stefano; Pascazio, Saverio
2009-12-01
We study maximally multipartite-entangled states in the context of Gaussian continuous variable quantum systems. By considering multimode Gaussian states with constrained energy, we show that perfect maximally multipartite-entangled states, which exhibit the maximum amount of bipartite entanglement for all bipartitions, only exist for systems containing n=2 or 3 modes. We further numerically investigate the structure of these states and their frustration for n≤7 .
Gaussian maximally multipartite-entangled states
International Nuclear Information System (INIS)
Facchi, Paolo; Florio, Giuseppe; Pascazio, Saverio; Lupo, Cosmo; Mancini, Stefano
2009-01-01
We study maximally multipartite-entangled states in the context of Gaussian continuous variable quantum systems. By considering multimode Gaussian states with constrained energy, we show that perfect maximally multipartite-entangled states, which exhibit the maximum amount of bipartite entanglement for all bipartitions, only exist for systems containing n=2 or 3 modes. We further numerically investigate the structure of these states and their frustration for n≤7.
Neutrino mass textures with maximal CP violation
International Nuclear Information System (INIS)
Aizawa, Ichiro; Kitabayashi, Teruyuki; Yasue, Masaki
2005-01-01
We show three types of neutrino mass textures, which give maximal CP violation as well as maximal atmospheric neutrino mixing. These textures are described by six real mass parameters: one specified by two complex flavor neutrino masses and two constrained ones and the others specified by three complex flavor neutrino masses. In each texture, we calculate mixing angles and masses, which are consistent with observed data, as well as Majorana CP phases
Why firms should not always maximize profits
Kolstad, Ivar
2006-01-01
Though corporate social responsibility (CSR) is on the agenda of most major corporations, corporate executives still largely support the view that corporations should maximize the returns to their owners. There are two lines of defence for this position. One is the Friedmanian view that maximizing owner returns is the corporate social responsibility of corporations. The other is a position voiced by many executives, that CSR and profits go together. This paper argues that the first position i...
Maximally Informative Observables and Categorical Perception
Tsiang, Elaine
2012-01-01
We formulate the problem of perception in the framework of information theory, and prove that categorical perception is equivalent to the existence of an observable that has the maximum possible information on the target of perception. We call such an observable maximally informative. Regardless whether categorical perception is real, maximally informative observables can form the basis of a theory of perception. We conclude with the implications of such a theory for the problem of speech per...
Validity of Linder Hypothesis in Bric Countries
Directory of Open Access Journals (Sweden)
Rana Atabay
2016-03-01
Full Text Available In this study, the theory of similarity in preferences (Linder hypothesis has been introduced and trade in BRIC countries has been examined whether the trade between these countries was valid for this hypothesis. Using the data for the period 1996 – 2010, the study applies to panel data analysis in order to provide evidence regarding the empirical validity of the Linder hypothesis for BRIC countries’ international trade. Empirical findings show that the trade between BRIC countries is in support of Linder hypothesis.
Shareholder, stakeholder-owner or broad stakeholder maximization
Mygind, Niels
2004-01-01
With reference to the discussion about shareholder versus stakeholder maximization it is argued that the normal type of maximization is in fact stakeholder-owner maxi-mization. This means maximization of the sum of the value of the shares and stake-holder benefits belonging to the dominating stakeholder-owner. Maximization of shareholder value is a special case of owner-maximization, and only under quite re-strictive assumptions shareholder maximization is larger or equal to stakeholder-owner...
Hypothesis Testing in the Real World
Miller, Jeff
2017-01-01
Critics of null hypothesis significance testing suggest that (a) its basic logic is invalid and (b) it addresses a question that is of no interest. In contrast to (a), I argue that the underlying logic of hypothesis testing is actually extremely straightforward and compelling. To substantiate that, I present examples showing that hypothesis…
Error probabilities in default Bayesian hypothesis testing
Gu, Xin; Hoijtink, Herbert; Mulder, J,
2016-01-01
This paper investigates the classical type I and type II error probabilities of default Bayes factors for a Bayesian t test. Default Bayes factors quantify the relative evidence between the null hypothesis and the unrestricted alternative hypothesis without needing to specify prior distributions for
Reassessing the Trade-off Hypothesis
DEFF Research Database (Denmark)
Rosas, Guillermo; Manzetti, Luigi
2015-01-01
Do economic conditions drive voters to punish politicians that tolerate corruption? Previous scholarly work contends that citizens in young democracies support corrupt governments that are capable of promoting good economic outcomes, the so-called trade-off hypothesis. We test this hypothesis based...
Mastery Learning and the Decreasing Variability Hypothesis.
Livingston, Jennifer A.; Gentile, J. Ronald
1996-01-01
This report results from studies that tested two variations of Bloom's decreasing variability hypothesis using performance on successive units of achievement in four graduate classrooms that used mastery learning procedures. Data do not support the decreasing variability hypothesis; rather, they show no change over time. (SM)
Vacua of maximal gauged D=3 supergravities
International Nuclear Information System (INIS)
Fischbacher, T; Nicolai, H; Samtleben, H
2002-01-01
We analyse the scalar potentials of maximal gauged three-dimensional supergravities which reveal a surprisingly rich structure. In contrast to maximal supergravities in dimensions D≥4, all these theories possess a maximally supersymmetric (N=16) ground state with negative cosmological constant Λ 2 gauged theory, whose maximally supersymmetric groundstate has Λ = 0. We compute the mass spectra of bosonic and fermionic fluctuations around these vacua and identify the unitary irreducible representations of the relevant background (super)isometry groups to which they belong. In addition, we find several stationary points which are not maximally supersymmetric, and determine their complete mass spectra as well. In particular, we show that there are analogues of all stationary points found in higher dimensions, among them are de Sitter (dS) vacua in the theories with noncompact gauge groups SO(5, 3) 2 and SO(4, 4) 2 , as well as anti-de Sitter (AdS) vacua in the compact gauged theory preserving 1/4 and 1/8 of the supersymmetries. All the dS vacua have tachyonic instabilities, whereas there do exist nonsupersymmetric AdS vacua which are stable, again in contrast to the D≥4 theories
An information maximization model of eye movements
Renninger, Laura Walker; Coughlan, James; Verghese, Preeti; Malik, Jitendra
2005-01-01
We propose a sequential information maximization model as a general strategy for programming eye movements. The model reconstructs high-resolution visual information from a sequence of fixations, taking into account the fall-off in resolution from the fovea to the periphery. From this framework we get a simple rule for predicting fixation sequences: after each fixation, fixate next at the location that minimizes uncertainty (maximizes information) about the stimulus. By comparing our model performance to human eye movement data and to predictions from a saliency and random model, we demonstrate that our model is best at predicting fixation locations. Modeling additional biological constraints will improve the prediction of fixation sequences. Our results suggest that information maximization is a useful principle for programming eye movements.
Utility Maximization in Nonconvex Wireless Systems
Brehmer, Johannes
2012-01-01
This monograph formulates a framework for modeling and solving utility maximization problems in nonconvex wireless systems. First, a model for utility optimization in wireless systems is defined. The model is general enough to encompass a wide array of system configurations and performance objectives. Based on the general model, a set of methods for solving utility maximization problems is developed. The development is based on a careful examination of the properties that are required for the application of each method. The focus is on problems whose initial formulation does not allow for a solution by standard convex methods. Solution approaches that take into account the nonconvexities inherent to wireless systems are discussed in detail. The monograph concludes with two case studies that demonstrate the application of the proposed framework to utility maximization in multi-antenna broadcast channels.
Maximizing band gaps in plate structures
DEFF Research Database (Denmark)
Halkjær, Søren; Sigmund, Ole; Jensen, Jakob Søndergaard
2006-01-01
periodic plate using Bloch theory, which conveniently reduces the maximization problem to that of a single base cell. Secondly, we construct a finite periodic plate using a number of the optimized base cells in a postprocessed version. The dynamic properties of the finite plate are investigated......Band gaps, i.e., frequency ranges in which waves cannot propagate, can be found in elastic structures for which there is a certain periodic modulation of the material properties or structure. In this paper, we maximize the band gap size for bending waves in a Mindlin plate. We analyze an infinite...... theoretically and experimentally and the issue of finite size effects is addressed....
Singularity Structure of Maximally Supersymmetric Scattering Amplitudes
DEFF Research Database (Denmark)
Arkani-Hamed, Nima; Bourjaily, Jacob L.; Cachazo, Freddy
2014-01-01
We present evidence that loop amplitudes in maximally supersymmetric (N=4) Yang-Mills theory (SYM) beyond the planar limit share some of the remarkable structures of the planar theory. In particular, we show that through two loops, the four-particle amplitude in full N=4 SYM has only logarithmic ...... singularities and is free of any poles at infinity—properties closely related to uniform transcendentality and the UV finiteness of the theory. We also briefly comment on implications for maximal (N=8) supergravity theory (SUGRA)....
Learning curves for mutual information maximization
International Nuclear Information System (INIS)
Urbanczik, R.
2003-01-01
An unsupervised learning procedure based on maximizing the mutual information between the outputs of two networks receiving different but statistically dependent inputs is analyzed [S. Becker and G. Hinton, Nature (London) 355, 161 (1992)]. For a generic data model, I show that in the large sample limit the structure in the data is recognized by mutual information maximization. For a more restricted model, where the networks are similar to perceptrons, I calculate the learning curves for zero-temperature Gibbs learning. These show that convergence can be rather slow, and a way of regularizing the procedure is considered
Finding Maximal Pairs with Bounded Gap
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Lyngsø, Rune B.; Pedersen, Christian N. S.
1999-01-01
. In this paper we present methods for finding all maximal pairs under various constraints on the gap. In a string of length n we can find all maximal pairs with gap in an upper and lower bounded interval in time O(n log n+z) where z is the number of reported pairs. If the upper bound is removed the time reduces...... to O(n+z). Since a tandem repeat is a pair where the gap is zero, our methods can be seen as a generalization of finding tandem repeats. The running time of our methods equals the running time of well known methods for finding tandem repeats....
International Nuclear Information System (INIS)
Maassberg, H.; Burhenn, R.; Gasparino, U.; Kuehner, G.; Ringler, H.; Dyabilin, K.S.
1993-01-01
The electron energy balance is analyzed for equivalent low-density electron cyclotron resonance heated (ECRH) discharges with highly peaked central power deposition in the stellarators W7-A [Plasma Phys. Controlled Fusion 28, 43 (1986)], L-2 [Proceedings of the 6th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Berchtesgaden, 1976 (International Atomic Energy Agency, Vienna, 1977), Vol. 2, p. 115] and W7-AS [Proceedings of the 9th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Baltimore, 1982 (International Atomic Energy Agency, Vienna, 1983), Vol. 3, p. 141]. Within the long mean-free path (LMFP) collisionality regime in stellarators, the neoclassical electron heat diffusivity χ e can overcome the ''anomalous'' one. The neoclassical transport coefficients are calculated by the DKES code (Drift Kinetic Equation Solver) [Phys. Fluids 29, 2951 (1986); Phys. Fluids B 1, 563 (1989)] for these configurations, and the particle and energy fluxes are estimated based on measured density and temperature profiles
How data-ink maximization can motivate learners – Persuasion in data visualization
Gottschalk, Judith
2017-01-01
This paper discusses both the macro- and the micro-level of persuasion in data visualizations in persuasive tools for language learning. The hypothesis of this paper is that persuasive data visualizations decrease reading time and increase reading accuracy of graph charts. Based on Tufte’s (1983) data-ink maximization principle the report introduces a framework for persuasive data visualizations on the persuasive micro level which employs Few’s (2013) conception of de-emphasizing non-data and...
Fitzpatrick, Richard
2018-04-01
A two-fluid, neoclassical theory of the interaction of a single magnetic island chain with a resonant error-field in a quasi-cylindrical, low-β, tokamak plasma is presented. The plasmas typically found in large hot tokamaks lie in the so-called weak neoclassical flow-damping regime in which the neoclassical ion stress tensor is not the dominant term in the ion parallel equation of motion. Nevertheless, flow-damping in such plasmas dominates ion perpendicular viscosity, and is largely responsible for determining the phase velocity of a freely rotating island chain (which is in the ion diamagnetic direction relative to the local E × B frame at the rational surface). The critical vacuum island width required to lock the island chain is mostly determined by the ion neoclassical poloidal flow damping rate at the rational surface. The stabilizing effect of the average field-line curvature, as well as the destabilizing effect of the perturbed bootstrap current, is the same for a freely rotating, a non-uniformly rotating, and a locked island chain. The destabilizing effect of the error-field averages to zero when the chain is rotating and only manifests itself when the chain locks. The perturbed ion polarization current has a small destabilizing effect on a freely rotating island chain, but a large destabilizing effect on both a non-uniformly rotating and a locked island chain. This behavior may account for the experimentally observed fact that locked island chains are much more unstable than corresponding freely rotating chains.
Maximizing the Range of a Projectile.
Brown, Ronald A.
1992-01-01
Discusses solutions to the problem of maximizing the range of a projectile. Presents three references that solve the problem with and without the use of calculus. Offers a fourth solution suitable for introductory physics courses that relies more on trigonometry and the geometry of the problem. (MDH)
Robust Utility Maximization Under Convex Portfolio Constraints
International Nuclear Information System (INIS)
Matoussi, Anis; Mezghani, Hanen; Mnif, Mohamed
2015-01-01
We study a robust maximization problem from terminal wealth and consumption under a convex constraints on the portfolio. We state the existence and the uniqueness of the consumption–investment strategy by studying the associated quadratic backward stochastic differential equation. We characterize the optimal control by using the duality method and deriving a dynamic maximum principle
Ehrenfest's Lottery--Time and Entropy Maximization
Ashbaugh, Henry S.
2010-01-01
Successful teaching of the Second Law of Thermodynamics suffers from limited simple examples linking equilibrium to entropy maximization. I describe a thought experiment connecting entropy to a lottery that mixes marbles amongst a collection of urns. This mixing obeys diffusion-like dynamics. Equilibrium is achieved when the marble distribution is…
Reserve design to maximize species persistence
Robert G. Haight; Laurel E. Travis
2008-01-01
We develop a reserve design strategy to maximize the probability of species persistence predicted by a stochastic, individual-based, metapopulation model. Because the population model does not fit exact optimization procedures, our strategy involves deriving promising solutions from theory, obtaining promising solutions from a simulation optimization heuristic, and...
Maximal indecomposable past sets and event horizons
International Nuclear Information System (INIS)
Krolak, A.
1984-01-01
The existence of maximal indecomposable past sets MIPs is demonstrated using the Kuratowski-Zorn lemma. A criterion for the existence of an absolute event horizon in space-time is given in terms of MIPs and a relation to black hole event horizon is shown. (author)
Maximization of eigenvalues using topology optimization
DEFF Research Database (Denmark)
Pedersen, Niels Leergaard
2000-01-01
to localized modes in low density areas. The topology optimization problem is formulated using the SIMP method. Special attention is paid to a numerical method for removing localized eigenmodes in low density areas. The method is applied to numerical examples of maximizing the first eigenfrequency, One example...
Maximizing Resource Utilization in Video Streaming Systems
Alsmirat, Mohammad Abdullah
2013-01-01
Video streaming has recently grown dramatically in popularity over the Internet, Cable TV, and wire-less networks. Because of the resource demanding nature of video streaming applications, maximizing resource utilization in any video streaming system is a key factor to increase the scalability and decrease the cost of the system. Resources to…
A THEORY OF MAXIMIZING SENSORY INFORMATION
Hateren, J.H. van
1992-01-01
A theory is developed on the assumption that early sensory processing aims at maximizing the information rate in the channels connecting the sensory system to more central parts of the brain, where it is assumed that these channels are noisy and have a limited dynamic range. Given a stimulus power
Maximizing scientific knowledge from randomized clinical trials
DEFF Research Database (Denmark)
Gustafsson, Finn; Atar, Dan; Pitt, Bertram
2010-01-01
Trialists have an ethical and financial responsibility to plan and conduct clinical trials in a manner that will maximize the scientific knowledge gained from the trial. However, the amount of scientific information generated by randomized clinical trials in cardiovascular medicine is highly vari...
A Model of College Tuition Maximization
Bosshardt, Donald I.; Lichtenstein, Larry; Zaporowski, Mark P.
2009-01-01
This paper develops a series of models for optimal tuition pricing for private colleges and universities. The university is assumed to be a profit maximizing, price discriminating monopolist. The enrollment decision of student's is stochastic in nature. The university offers an effective tuition rate, comprised of stipulated tuition less financial…
Logit Analysis for Profit Maximizing Loan Classification
Watt, David L.; Mortensen, Timothy L.; Leistritz, F. Larry
1988-01-01
Lending criteria and loan classification methods are developed. Rating system breaking points are analyzed to present a method to maximize loan revenues. Financial characteristics of farmers are used as determinants of delinquency in a multivariate logistic model. Results indicate that debt-to-asset and operating ration are most indicative of default.
Developing maximal neuromuscular power: Part 1--biological basis of maximal power production.
Cormie, Prue; McGuigan, Michael R; Newton, Robert U
2011-01-01
This series of reviews focuses on the most important neuromuscular function in many sport performances, the ability to generate maximal muscular power. Part 1 focuses on the factors that affect maximal power production, while part 2, which will follow in a forthcoming edition of Sports Medicine, explores the practical application of these findings by reviewing the scientific literature relevant to the development of training programmes that most effectively enhance maximal power production. The ability of the neuromuscular system to generate maximal power is affected by a range of interrelated factors. Maximal muscular power is defined and limited by the force-velocity relationship and affected by the length-tension relationship. The ability to generate maximal power is influenced by the type of muscle action involved and, in particular, the time available to develop force, storage and utilization of elastic energy, interactions of contractile and elastic elements, potentiation of contractile and elastic filaments as well as stretch reflexes. Furthermore, maximal power production is influenced by morphological factors including fibre type contribution to whole muscle area, muscle architectural features and tendon properties as well as neural factors including motor unit recruitment, firing frequency, synchronization and inter-muscular coordination. In addition, acute changes in the muscle environment (i.e. alterations resulting from fatigue, changes in hormone milieu and muscle temperature) impact the ability to generate maximal power. Resistance training has been shown to impact each of these neuromuscular factors in quite specific ways. Therefore, an understanding of the biological basis of maximal power production is essential for developing training programmes that effectively enhance maximal power production in the human.
International Nuclear Information System (INIS)
Groebner, R.J.
1986-04-01
The study of ion transport in neutral beam-heated discharges in tokamaks is necessary to determine if neoclassical theory can reliably be used to predict the performance of future machines. Previous studies of ion tranport have generally been difficult due to the lack of information regarding the ion temperature profile. The standard procedure used to study ion transport has been to model the T/sub i/ profile with the assumption that the ion thermal diffusivity profile chi/sub i/(r) was equal to a multiplier times chi/sub i//sup neo/(r), the ion thermal diffusivity calculated from neoclassical theory. The multiplier was varied until the calculated T/sub i/ profile agreed with the available ion temperature data, usually T/sub i/(0) or the measured neutron rate. Values of the multiplier in the range of 1 to 10 have generally been obtained with few estimates of the uncertainties in these values. Furthermore, there have been few, if any, attempts to calculate chi/sub i/ by modeling the ion temperature profiles in other ways. As a result, the issue as to whether or not the ion transport in tokamaks is in agreement with neoclassical theory has not been definitively answered
Understanding Violations of Gricean Maxims in Preschoolers and Adults
Directory of Open Access Journals (Sweden)
Mako eOkanda
2015-07-01
Full Text Available This study used a revised Conversational Violations Test to examine Gricean maxim violations in 4- to 6-year-old Japanese children and adults. Participants’ understanding of the following maxims was assessed: be informative (first maxim of quantity, avoid redundancy (second maxim of quantity, be truthful (maxim of quality, be relevant (maxim of relation, avoid ambiguity (second maxim of manner, and be polite (maxim of politeness. Sensitivity to violations of Gricean maxims increased with age: 4-year-olds’ understanding of maxims was near chance, 5-year-olds understood some maxims (first maxim of quantity and maxims of quality, relation, and manner, and 6-year-olds and adults understood all maxims. Preschoolers acquired the maxim of relation first and had the greatest difficulty understanding the second maxim of quantity. Children and adults differed in their comprehension of the maxim of politeness. The development of the pragmatic understanding of Gricean maxims and implications for the construction of developmental tasks from early childhood to adulthood are discussed.
Implications of the Bohm-Aharonov hypothesis
International Nuclear Information System (INIS)
Ghirardi, G.C.; Rimini, A.; Weber, T.
1976-01-01
It is proved that the Bohm-Aharonov hypothesis concerning largerly separated subsystems of composite quantum systems implies that it is impossible to express the dynamical evolution in terms of the density operator
Multi-agent sequential hypothesis testing
Kim, Kwang-Ki K.; Shamma, Jeff S.
2014-01-01
incorporate costs of taking private/public measurements, costs of time-difference and disagreement in actions of agents, and costs of false declaration/choices in the sequential hypothesis testing. The corresponding sequential decision processes have well
How organisms do the right thing: The attractor hypothesis
Emlen, J.M.; Freeman, D.C.; Mills, A.; Graham, J.H.
1998-01-01
Neo-Darwinian theory is highly successful at explaining the emergence of adaptive traits over successive generations. However, there are reasons to doubt its efficacy in explaining the observed, impressively detailed adaptive responses of organisms to day-to-day changes in their surroundings. Also, the theory lacks a clear mechanism to account for both plasticity and canalization. In effect, there is a growing sentiment that the neo-Darwinian paradigm is incomplete, that something more than genetic structure, mutation, genetic drift, and the action of natural selection is required to explain organismal behavior. In this paper we extend the view of organisms as complex self-organizing entities by arguing that basic physical laws, coupled with the acquisitive nature of organisms, makes adaptation all but tautological. That is, much adaptation is an unavoidable emergent property of organisms' complexity and, to some a significant degree, occurs quite independently of genomic changes wrought by natural selection. For reasons that will become obvious, we refer to this assertion as the attractor hypothesis. The arguments also clarify the concept of "adaptation." Adaptation across generations, by natural selection, equates to the (game theoretic) maximization of fitness (the success with which one individual produces more individuals), while self-organizing based adaptation, within generations, equates to energetic efficiency and the matching of intake and biosynthesis to need. Finally, we discuss implications of the attractor hypothesis for a wide variety of genetical and physiological phenomena, including genetic architecture, directed mutation, genetic imprinting, paramutation, hormesis, plasticity, optimality theory, genotype-phenotype linkage and puncuated equilibrium, and present suggestions for tests of the hypothesis. ?? 1998 American Institute of Physics.
The (not so) Immortal Strand Hypothesis
Tomasetti, Cristian; Bozic, Ivana
2015-01-01
Background: Non-random segregation of DNA strands during stem cell replication has been proposed as a mechanism to minimize accumulated genetic errors in stem cells of rapidly dividing tissues. According to this hypothesis, an “immortal” DNA strand is passed to the stem cell daughter and not the more differentiated cell, keeping the stem cell lineage replication error-free. After it was introduced, experimental evidence both in favor and against the hypothesis has been presented. Principal...
Energy Technology Data Exchange (ETDEWEB)
Dorf, M. A.; Cohen, R. H.; Joseph, I. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Simakov, A. N. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
2013-08-15
The use of the standard approaches for evaluating a neoclassical radial electric field E{sub r}, i.e., the Ampere (or gyro-Poisson) equation, requires accurate calculation of the difference between the gyroaveraged electron and ion particle fluxes (or densities). In the core of a tokamak, the nontrivial difference appears only in high-order corrections to a local Maxwellian distribution due to the intrinsic ambipolarity of particle transport. The evaluation of such high-order corrections may be inconsistent with the accuracy of the standard long wavelength gyrokinetic equation (GKE), thus imposing limitations on the applicability of the standard approaches. However, in the edge of a tokamak, charge-exchange collisions with neutrals and prompt ion orbit losses can drive non-intrinsically ambipolar particle fluxes for which a nontrivial (E{sub r}-dependent) difference between the electron and ion fluxes appears already in a low order and can be accurately predicted by the long wavelength GKE. The parameter regimes, where the radial electric field dynamics in the tokamak edge region is dominated by the non-intrinsically ambipolar processes, thus allowing for the use of the standard approaches, are discussed.
International Nuclear Information System (INIS)
Chang, C.S.; Hammett, G.W.; Goldston, R.J.
1990-01-01
Neoclassical transport of energetic minority tail ions, which are generated by high powered electromagnetic waves of the Ion Cyclotron Range of Frequencies (ICRF) at the fundamental harmonic resonance, is studied analytically in tokamak geometry. The effect of Coulomb collisions on the tail ion transport is investigated in the present work. The total tail ion transport will be the sum of the present collision-driven transport and the wave-driven transport, which is due to the ICRF-wave scattering of the tail particles as reported in the literature. The transport coefficients have been calculated kinetically, and it is found that the large tail ion viscosity, driven by the localized ICRF-heating and Coulomb slowing-down collisions, induces purely convective particle transport of the tail species, while the energy transport is both convective and diffusive. The rate of radial particle transport is shown to be usually small, but the rate of radial energy transport is larger and may not be negligible compared to the Coulomb slowing-down rate. 18 refs., 2 figs
Kwon, Jae-Min; Ku, S.; Choi, M. J.; Chang, C. S.; Hager, R.; Yoon, E. S.; Lee, H. H.; Kim, H. S.
2018-05-01
We perform gyrokinetic simulations to study the effects of a stationary magnetic island on neoclassical flow and micro-instability in a realistic KSTAR plasma condition. Through the simulations, we aim to analyze a recent KSTAR experiment, which was to measure the details of poloidal flow and fluctuation around a stationary (2, 1) magnetic island [M. J. Choi et al., Nucl. Fusion 57, 126058 (2017)]. From the simulations, it is found that the magnetic island can significantly enhance the equilibrium E × B flow. The corresponding flow shearing is strong enough to suppress a substantial portion of ambient micro-instabilities, particularly ∇Te -driven trapped electron modes. This implies that the enhanced E × B flow can sustain a quasi-internal transport barrier for Te in an inner region neighboring the magnetic island. The enhanced E × B flow has a (2, 1) mode structure with a finite phase shift from the mode structure of the magnetic island. It is shown that the flow shear and the fluctuation suppression patterns implied from the simulations are consistent with the observations on the KSTAR experiment.
International Nuclear Information System (INIS)
Kovrizhnykh, L.M.
1984-01-01
The paper constitutes a review of the neoclassical theory of transport processes in the different types of toroidal magnetic configuration now being used to study the possibility of producing a controlled thermonuclear reaction. Owing to the abundance of the material that has accumulated in recent years and the large number of parameters involved in the problem, it has not been possible to present all the mathematical calculations in detail while confining the results to a few definitive expressions. The general approach to a solution of the problem and its key aspects have been discussed as fully as possible, and a number of definitive results are presented. In the review, a history of the subject and an account of its present status are given, the problem itself is formulated, the basic equations are discussed and analytical solution methods are described. Definitive expressions are given for cross-field particle and energy fluxes, the bootstrap current and conductivity, all of which are required to solve the particle and heat balance equations in magnetic confinement devices. The results are presented in a relatively simple form which is convenient for analysis of the experimental data and are accompanied by tables containing numerical values for the universal coefficients in the definitive expressions. The review is aimed at both theoreticians and experimenters working in high-temperature plasma physics and controlled thermonuclear fusion. (author)
Refined reservoir description to maximize oil recovery
International Nuclear Information System (INIS)
Flewitt, W.E.
1975-01-01
To assure maximized oil recovery from older pools, reservoir description has been advanced by fully integrating original open-hole logs and the recently introduced interpretive techniques made available through cased-hole wireline saturation logs. A refined reservoir description utilizing normalized original wireline porosity logs has been completed in the Judy Creek Beaverhill Lake ''A'' Pool, a reefal carbonate pool with current potential productivity of 100,000 BOPD and 188 active wells. Continuous porosity was documented within a reef rim and cap while discontinuous porous lenses characterized an interior lagoon. With the use of pulsed neutron logs and production data a separate water front and pressure response was recognized within discrete environmental units. The refined reservoir description aided in reservoir simulation model studies and quantifying pool performance. A pattern water flood has now replaced the original peripheral bottom water drive to maximize oil recovery
Maximal frustration as an immunological principle.
de Abreu, F Vistulo; Mostardinha, P
2009-03-06
A fundamental problem in immunology is that of understanding how the immune system selects promptly which cells to kill without harming the body. This problem poses an apparent paradox. Strong reactivity against pathogens seems incompatible with perfect tolerance towards self. We propose a different view on cellular reactivity to overcome this paradox: effector functions should be seen as the outcome of cellular decisions which can be in conflict with other cells' decisions. We argue that if cellular systems are frustrated, then extensive cross-reactivity among the elements in the system can decrease the reactivity of the system as a whole and induce perfect tolerance. Using numerical and mathematical analyses, we discuss two simple models that perform optimal pathogenic detection with no autoimmunity if cells are maximally frustrated. This study strongly suggests that a principle of maximal frustration could be used to build artificial immune systems. It would be interesting to test this principle in the real adaptive immune system.
Maximizing Statistical Power When Verifying Probabilistic Forecasts of Hydrometeorological Events
DeChant, C. M.; Moradkhani, H.
2014-12-01
Hydrometeorological events (i.e. floods, droughts, precipitation) are increasingly being forecasted probabilistically, owing to the uncertainties in the underlying causes of the phenomenon. In these forecasts, the probability of the event, over some lead time, is estimated based on some model simulations or predictive indicators. By issuing probabilistic forecasts, agencies may communicate the uncertainty in the event occurring. Assuming that the assigned probability of the event is correct, which is referred to as a reliable forecast, the end user may perform some risk management based on the potential damages resulting from the event. Alternatively, an unreliable forecast may give false impressions of the actual risk, leading to improper decision making when protecting resources from extreme events. Due to this requisite for reliable forecasts to perform effective risk management, this study takes a renewed look at reliability assessment in event forecasts. Illustrative experiments will be presented, showing deficiencies in the commonly available approaches (Brier Score, Reliability Diagram). Overall, it is shown that the conventional reliability assessment techniques do not maximize the ability to distinguish between a reliable and unreliable forecast. In this regard, a theoretical formulation of the probabilistic event forecast verification framework will be presented. From this analysis, hypothesis testing with the Poisson-Binomial distribution is the most exact model available for the verification framework, and therefore maximizes one's ability to distinguish between a reliable and unreliable forecast. Application of this verification system was also examined within a real forecasting case study, highlighting the additional statistical power provided with the use of the Poisson-Binomial distribution.
Derivative pricing based on local utility maximization
Jan Kallsen
2002-01-01
This paper discusses a new approach to contingent claim valuation in general incomplete market models. We determine the neutral derivative price which occurs if investors maximize their local utility and if derivative demand and supply are balanced. We also introduce the sensitivity process of a contingent claim. This process quantifies the reliability of the neutral derivative price and it can be used to construct price bounds. Moreover, it allows to calibrate market models in order to be co...
Control of Shareholders’ Wealth Maximization in Nigeria
A. O. Oladipupo; C. O. Okafor
2014-01-01
This research focuses on who controls shareholder’s wealth maximization and how does this affect firm’s performance in publicly quoted non-financial companies in Nigeria. The shareholder fund was the dependent while explanatory variables were firm size (proxied by log of turnover), retained earning (representing management control) and dividend payment (representing measure of shareholders control). The data used for this study were obtained from the Nigerian Stock Exchange [NSE] fact book an...
Definable maximal discrete sets in forcing extensions
DEFF Research Database (Denmark)
Törnquist, Asger Dag; Schrittesser, David
2018-01-01
Let be a Σ11 binary relation, and recall that a set A is -discrete if no two elements of A are related by . We show that in the Sacks and Miller forcing extensions of L there is a Δ12 maximal -discrete set. We use this to answer in the negative the main question posed in [5] by showing...
Dynamic Convex Duality in Constrained Utility Maximization
Li, Yusong; Zheng, Harry
2016-01-01
In this paper, we study a constrained utility maximization problem following the convex duality approach. After formulating the primal and dual problems, we construct the necessary and sufficient conditions for both the primal and dual problems in terms of FBSDEs plus additional conditions. Such formulation then allows us to explicitly characterize the primal optimal control as a function of the adjoint process coming from the dual FBSDEs in a dynamic fashion and vice versa. Moreover, we also...
Single maximal versus combination punch kinematics.
Piorkowski, Barry A; Lees, Adrian; Barton, Gabor J
2011-03-01
The aim of this study was to determine the influence of punch type (Jab, Cross, Lead Hook and Reverse Hook) and punch modality (Single maximal, 'In-synch' and 'Out of synch' combination) on punch speed and delivery time. Ten competition-standard volunteers performed punches with markers placed on their anatomical landmarks for 3D motion capture with an eight-camera optoelectronic system. Speed and duration between key moments were computed. There were significant differences in contact speed between punch types (F(2,18,84.87) = 105.76, p = 0.001) with Lead and Reverse Hooks developing greater speed than Jab and Cross. There were significant differences in contact speed between punch modalities (F(2,64,102.87) = 23.52, p = 0.001) with the Single maximal (M+/- SD: 9.26 +/- 2.09 m/s) higher than 'Out of synch' (7.49 +/- 2.32 m/s), 'In-synch' left (8.01 +/- 2.35 m/s) or right lead (7.97 +/- 2.53 m/s). Delivery times were significantly lower for Jab and Cross than Hook. Times were significantly lower 'In-synch' than a Single maximal or 'Out of synch' combination mode. It is concluded that a defender may have more evasion-time than previously reported. This research could be of use to performers and coaches when considering training preparations.
Formation Control for the MAXIM Mission
Luquette, Richard J.; Leitner, Jesse; Gendreau, Keith; Sanner, Robert M.
2004-01-01
Over the next twenty years, a wave of change is occurring in the space-based scientific remote sensing community. While the fundamental limits in the spatial and angular resolution achievable in spacecraft have been reached, based on today s technology, an expansive new technology base has appeared over the past decade in the area of Distributed Space Systems (DSS). A key subset of the DSS technology area is that which covers precision formation flying of space vehicles. Through precision formation flying, the baselines, previously defined by the largest monolithic structure which could fit in the largest launch vehicle fairing, are now virtually unlimited. Several missions including the Micro-Arcsecond X-ray Imaging Mission (MAXIM), and the Stellar Imager will drive the formation flying challenges to achieve unprecedented baselines for high resolution, extended-scene, interferometry in the ultraviolet and X-ray regimes. This paper focuses on establishing the feasibility for the formation control of the MAXIM mission. MAXIM formation flying requirements are on the order of microns, while Stellar Imager mission requirements are on the order of nanometers. This paper specifically addresses: (1) high-level science requirements for these missions and how they evolve into engineering requirements; and (2) the development of linearized equations of relative motion for a formation operating in an n-body gravitational field. Linearized equations of motion provide the ground work for linear formation control designs.
Gradient Dynamics and Entropy Production Maximization
Janečka, Adam; Pavelka, Michal
2018-01-01
We compare two methods for modeling dissipative processes, namely gradient dynamics and entropy production maximization. Both methods require similar physical inputs-how energy (or entropy) is stored and how it is dissipated. Gradient dynamics describes irreversible evolution by means of dissipation potential and entropy, it automatically satisfies Onsager reciprocal relations as well as their nonlinear generalization (Maxwell-Onsager relations), and it has statistical interpretation. Entropy production maximization is based on knowledge of free energy (or another thermodynamic potential) and entropy production. It also leads to the linear Onsager reciprocal relations and it has proven successful in thermodynamics of complex materials. Both methods are thermodynamically sound as they ensure approach to equilibrium, and we compare them and discuss their advantages and shortcomings. In particular, conditions under which the two approaches coincide and are capable of providing the same constitutive relations are identified. Besides, a commonly used but not often mentioned step in the entropy production maximization is pinpointed and the condition of incompressibility is incorporated into gradient dynamics.
Multiple hypothesis tracking for the cyber domain
Schwoegler, Stefan; Blackman, Sam; Holsopple, Jared; Hirsch, Michael J.
2011-09-01
This paper discusses how methods used for conventional multiple hypothesis tracking (MHT) can be extended to domain-agnostic tracking of entities from non-kinematic constraints such as those imposed by cyber attacks in a potentially dense false alarm background. MHT is widely recognized as the premier method to avoid corrupting tracks with spurious data in the kinematic domain but it has not been extensively applied to other problem domains. The traditional approach is to tightly couple track maintenance (prediction, gating, filtering, probabilistic pruning, and target confirmation) with hypothesis management (clustering, incompatibility maintenance, hypothesis formation, and Nassociation pruning). However, by separating the domain specific track maintenance portion from the domain agnostic hypothesis management piece, we can begin to apply the wealth of knowledge gained from ground and air tracking solutions to the cyber (and other) domains. These realizations led to the creation of Raytheon's Multiple Hypothesis Extensible Tracking Architecture (MHETA). In this paper, we showcase MHETA for the cyber domain, plugging in a well established method, CUBRC's INFormation Engine for Real-time Decision making, (INFERD), for the association portion of the MHT. The result is a CyberMHT. We demonstrate the power of MHETA-INFERD using simulated data. Using metrics from both the tracking and cyber domains, we show that while no tracker is perfect, by applying MHETA-INFERD, advanced nonkinematic tracks can be captured in an automated way, perform better than non-MHT approaches, and decrease analyst response time to cyber threats.
Aminoglycoside antibiotics and autism: a speculative hypothesis
Directory of Open Access Journals (Sweden)
Manev Hari
2001-10-01
Full Text Available Abstract Background Recently, it has been suspected that there is a relationship between therapy with some antibiotics and the onset of autism; but even more curious, some children benefited transiently from a subsequent treatment with a different antibiotic. Here, we speculate how aminoglycoside antibiotics might be associated with autism. Presentation We hypothesize that aminoglycoside antibiotics could a trigger the autism syndrome in susceptible infants by causing the stop codon readthrough, i.e., a misreading of the genetic code of a hypothetical critical gene, and/or b improve autism symptoms by correcting the premature stop codon mutation in a hypothetical polymorphic gene linked to autism. Testing Investigate, retrospectively, whether a link exists between aminoglycoside use (which is not extensive in children and the onset of autism symptoms (hypothesis "a", or between amino glycoside use and improvement of these symptoms (hypothesis "b". Whereas a prospective study to test hypothesis "a" is not ethically justifiable, a study could be designed to test hypothesis "b". Implications It should be stressed that at this stage no direct evidence supports our speculative hypothesis and that its main purpose is to initiate development of new ideas that, eventually, would improve our understanding of the pathobiology of autism.
Cardiorespiratory Coordination in Repeated Maximal Exercise
Directory of Open Access Journals (Sweden)
Sergi Garcia-Retortillo
2017-06-01
Full Text Available Increases in cardiorespiratory coordination (CRC after training with no differences in performance and physiological variables have recently been reported using a principal component analysis approach. However, no research has yet evaluated the short-term effects of exercise on CRC. The aim of this study was to delineate the behavior of CRC under different physiological initial conditions produced by repeated maximal exercises. Fifteen participants performed 2 consecutive graded and maximal cycling tests. Test 1 was performed without any previous exercise, and Test 2 6 min after Test 1. Both tests started at 0 W and the workload was increased by 25 W/min in males and 20 W/min in females, until they were not able to maintain the prescribed cycling frequency of 70 rpm for more than 5 consecutive seconds. A principal component (PC analysis of selected cardiovascular and cardiorespiratory variables (expired fraction of O2, expired fraction of CO2, ventilation, systolic blood pressure, diastolic blood pressure, and heart rate was performed to evaluate the CRC defined by the number of PCs in both tests. In order to quantify the degree of coordination, the information entropy was calculated and the eigenvalues of the first PC (PC1 were compared between tests. Although no significant differences were found between the tests with respect to the performed maximal workload (Wmax, maximal oxygen consumption (VO2 max, or ventilatory threshold (VT, an increase in the number of PCs and/or a decrease of eigenvalues of PC1 (t = 2.95; p = 0.01; d = 1.08 was found in Test 2 compared to Test 1. Moreover, entropy was significantly higher (Z = 2.33; p = 0.02; d = 1.43 in the last test. In conclusion, despite the fact that no significant differences were observed in the conventionally explored maximal performance and physiological variables (Wmax, VO2 max, and VT between tests, a reduction of CRC was observed in Test 2. These results emphasize the interest of CRC
Testing competing forms of the Milankovitch hypothesis
DEFF Research Database (Denmark)
Kaufmann, Robert K.; Juselius, Katarina
2016-01-01
We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical...... ice volume and solar insolation. The estimated adjustment dynamics show that solar insolation affects an array of climate variables other than ice volume, each at a unique rate. This implies that previous efforts to test the strong form of the Milankovitch hypothesis by examining the relationship...... that the latter is consistent with a weak form of the Milankovitch hypothesis and that it should be restated as follows: Internal climate dynamics impose perturbations on glacial cycles that are driven by solar insolation. Our results show that these perturbations are likely caused by slow adjustment between land...
Rejecting the equilibrium-point hypothesis.
Gottlieb, G L
1998-01-01
The lambda version of the equilibrium-point (EP) hypothesis as developed by Feldman and colleagues has been widely used and cited with insufficient critical understanding. This article offers a small antidote to that lack. First, the hypothesis implicitly, unrealistically assumes identical transformations of lambda into muscle tension for antagonist muscles. Without that assumption, its definitions of command variables R, C, and lambda are incompatible and an EP is not defined exclusively by R nor is it unaffected by C. Second, the model assumes unrealistic and unphysiological parameters for the damping properties of the muscles and reflexes. Finally, the theory lacks rules for two of its three command variables. A theory of movement should offer insight into why we make movements the way we do and why we activate muscles in particular patterns. The EP hypothesis offers no unique ideas that are helpful in addressing either of these questions.
The linear hypothesis and radiation carcinogenesis
International Nuclear Information System (INIS)
Roberts, P.B.
1981-10-01
An assumption central to most estimations of the carcinogenic potential of low levels of ionising radiation is that the risk always increases in direct proportion to the dose received. This assumption (the linear hypothesis) has been both strongly defended and attacked on several counts. It appears unlikely that conclusive, direct evidence on the validity of the hypothesis will be forthcoming. We review the major indirect arguments used in the debate. All of them are subject to objections that can seriously weaken their case. In the present situation, retention of the linear hypothesis as the basis of extrapolations from high to low dose levels can lead to excessive fears, over-regulation and unnecessarily expensive protection measures. To offset these possibilities, support is given to suggestions urging a cut-off dose, probably some fraction of natural background, below which risks can be deemed acceptable
Rayleigh's hypothesis and the geometrical optics limit.
Elfouhaily, Tanos; Hahn, Thomas
2006-09-22
The Rayleigh hypothesis (RH) is often invoked in the theoretical and numerical treatment of rough surface scattering in order to decouple the analytical form of the scattered field. The hypothesis stipulates that the scattered field away from the surface can be extended down onto the rough surface even though it is formed by solely up-going waves. Traditionally this hypothesis is systematically used to derive the Volterra series under the small perturbation method which is equivalent to the low-frequency limit. In this Letter we demonstrate that the RH also carries the high-frequency or the geometrical optics limit, at least to first order. This finding has never been explicitly derived in the literature. Our result comforts the idea that the RH might be an exact solution under some constraints in the general case of random rough surfaces and not only in the case of small-slope deterministic periodic gratings.
International Nuclear Information System (INIS)
Guenter, S.; Gude, A.; Igochine, V.; Maraschek, M.; Sips, A.C.C.; Zohm, H.; Gantenbein, G.; Sauter, O.
2003-01-01
In this paper recent results on the physics of neoclassical tearing modes (NTMs) achieved on ASDEX Upgrade are reported. A scaling law for NTM decay has been found, showing that the minimum local bootstrap current density required for mode growth is proportional to the ion gyro radius. As this scaling law does not depend on the seed island size, and thus on the background MHD activity, it is more reliable than previously derived scaling laws for the NTM onset. Furthermore, the recently reported Frequently Interrupted Regime (FIR) is discussed. In this new regime (m,n) NTMs are characterized by frequent amplitude drops caused by interaction with (m+1,n+1) background MHD activity. Due to the resulting reduced time averaged island size this leads to lower confinement degradation compared to that caused by the usual NTMs. As shown here, the transition into this regime can actively be triggered by lowering the magnetic shear at the q=(m+1)/=(n+1) rational surface. Further investigations regard mechanisms to increase the β N value for NTM onset such as plasma shaping, seed island size and density profile control. Using these studies, a scenario with high β N (β N = 3:5) at high density (n/n GW = 0.83) and confinement (H 98(y,2) = 1.2) has been developed. Moreover, this scenario is characterized by type II ELM activity and thus by moderate heat load to the target plates. Finally, new NTM stabilization experiments are reported, demonstrating an increase in β N after NTM stabilization. (author)
Basiuk, V.; Huynh, P.; Merle, A.; Nowak, S.; Sauter, O.; Contributors, JET; the EUROfusion-IM Team
2017-12-01
The neoclassical tearing modes (NTM) increase the effective heat and particle radial transport inside the plasma, leading to a flattening of the electron and ion temperature and density profiles at a given location depending on the safety factor q rational surface (Hegna and Callen 1997 Phys. Plasmas 4 2940). In burning plasma such as in ITER, this NTM-induced increased transport could reduce significantly the fusion performance and even lead to a disruption. Validating models describing the NTM-induced transport in present experiment is thus important to help quantifying this effect on future devices. In this work, we apply an NTM model to an integrated simulation of current, heat and particle transport on JET discharges using the European transport simulator. In this model, the heat and particle radial transport coefficients are modified by a Gaussian function locally centered at the NTM position and characterized by a full width proportional to the island size through a constant parameter adapted to obtain the best simulations of experimental profiles. In the simulation, the NTM model is turned on at the same time as the mode is triggered in the experiment. The island evolution is itself determined by the modified Rutherford equation, using self-consistent plasma parameters determined by the transport evolution. The achieved simulation reproduces the experimental measurements within the error bars, before and during the NTM. A small discrepancy is observed on the radial location of the island due to a shift of the position of the computed q = 3/2 surface compared to the experimental one. To explain such small shift (up to about 12% with respect to the position observed from the experimental electron temperature profiles), sensitivity studies of the NTM location as a function of the initialization parameters are presented. First results validate both the transport model and the transport modification calculated by the NTM model.
International Nuclear Information System (INIS)
Dinklage, A.; Beidler, C.D.; Baldzuhn, J.; Feng, Y.; Geiger, J.; Jakubowski, M.; Maaßberg, H.; Yokoyama, M.; Tanaka, K.; Satake, S.; Ida, K.; Miyazawa, J.; Morisaki, T.; Velasco, J.L.; López-Bruna, D.; Ascasíbar, E.; Arévalo, J.; López-Fraguas, A.; Gates, D.; Isaev, M.
2013-01-01
A comparative study of energy transport for medium- to high-density discharges in the stellarator-heliotrons TJ-II, W7-AS and LHD is carried out. The specific discharge parameters are chosen to apply a recently concluded benchmarking study of neoclassical (NC) transport coefficients (Beidler et al 2011 Nucl. Fusion 51 076001) to perform this validation study. In contrast to previous experiments at low densities for which electron transport was predominant (Yokoyama et al 2007 Nucl. Fusion 47 1213), the current discharges also exhibit significant ion energy transport. As it affects the energy transport in 3D devices, the ambipolar radial electric field is addressed as well. For the discharges described, ion-root conditions, i.e. a small negative radial electric field were found. The energy transport in the peripheral region cannot be explained by NC theory. Within a ‘core region’(r/a < 1/2 ∼ 2/3), the predicted NC energy fluxes comply with experimental findings for W7-AS. For TJ-II, compliance in the core region is found for the particle transport and the electron energy transport. For the specific LHD discharges, the core energy transport complied with NC theory except for the electron energy transport in the inward-shifted magnetic configuration. The NC radial electric field tends to agree with experimental results for all devices but is measured to be more negative in the core of both LHD and TJ-II. As a general observation, the energy confinement time approaches the gyro-Bohm-type confinement scaling ISS04 (Yamada et al 2005 Nucl. Fusion 45 1684). This work is carried out within the International Stellarator-Heliotron Profile Database (www.ipp.mpg.de/ISS and http://ishpdb.nifs.ac.jp/index.html). (paper)
Energy Technology Data Exchange (ETDEWEB)
Hager, Robert, E-mail: rhager@pppl.gov; Chang, C. S., E-mail: cschang@pppl.gov [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)
2016-04-15
As a follow-up on the drift-kinetic study of the non-local bootstrap current in the steep edge pedestal of tokamak plasma by Koh et al. [Phys. Plasmas 19, 072505 (2012)], a gyrokinetic neoclassical study is performed with gyrokinetic ions and drift-kinetic electrons. Besides the gyrokinetic improvement of ion physics from the drift-kinetic treatment, a fully non-linear Fokker-Planck collision operator—that conserves mass, momentum, and energy—is used instead of Koh et al.'s linearized collision operator in consideration of the possibility that the ion distribution function is non-Maxwellian in the steep pedestal. An inaccuracy in Koh et al.'s result is found in the steep edge pedestal that originated from a small error in the collisional momentum conservation. The present study concludes that (1) the bootstrap current in the steep edge pedestal is generally smaller than what has been predicted from the small banana-width (local) approximation [e.g., Sauter et al., Phys. Plasmas 6, 2834 (1999) and Belli et al., Plasma Phys. Controlled Fusion 50, 095010 (2008)], (2) the plasma flow evaluated from the local approximation can significantly deviate from the non-local results, and (3) the bootstrap current in the edge pedestal, where the passing particle region is small, can be dominantly carried by the trapped particles in a broad trapped boundary layer. A new analytic formula based on numerous gyrokinetic simulations using various magnetic equilibria and plasma profiles with self-consistent Grad-Shafranov solutions is constructed.
Postactivation potentiation biases maximal isometric strength assessment.
Lima, Leonardo Coelho Rabello; Oliveira, Felipe Bruno Dias; Oliveira, Thiago Pires; Assumpção, Claudio de Oliveira; Greco, Camila Coelho; Cardozo, Adalgiso Croscato; Denadai, Benedito Sérgio
2014-01-01
Postactivation potentiation (PAP) is known to enhance force production. Maximal isometric strength assessment protocols usually consist of two or more maximal voluntary isometric contractions (MVCs). The objective of this study was to determine if PAP would influence isometric strength assessment. Healthy male volunteers (n = 23) performed two five-second MVCs separated by a 180-seconds interval. Changes in isometric peak torque (IPT), time to achieve it (tPTI), contractile impulse (CI), root mean square of the electromyographic signal during PTI (RMS), and rate of torque development (RTD), in different intervals, were measured. Significant increases in IPT (240.6 ± 55.7 N·m versus 248.9 ± 55.1 N·m), RTD (746 ± 152 N·m·s(-1) versus 727 ± 158 N·m·s(-1)), and RMS (59.1 ± 12.2% RMSMAX versus 54.8 ± 9.4% RMSMAX) were found on the second MVC. tPTI decreased significantly on the second MVC (2373 ± 1200 ms versus 2784 ± 1226 ms). We conclude that a first MVC leads to PAP that elicits significant enhancements in strength-related variables of a second MVC performed 180 seconds later. If disconsidered, this phenomenon might bias maximal isometric strength assessment, overestimating some of these variables.
On the generalized gravi-magnetic hypothesis
International Nuclear Information System (INIS)
Massa, C.
1989-01-01
According to a generalization of the gravi-magnetic hypothesis (GMH) any neutral mass moving in a curvilinear path with respect to an inertial frame creates a magnetic field, dependent on the curvature radius of the path. A simple astrophysical consequence of the generalized GMH is suggested considering the special cases of binary pulsars and binary neutron stars
Remarks about the hypothesis of limiting fragmentation
International Nuclear Information System (INIS)
Chou, T.T.; Yang, C.N.
1987-01-01
Remarks are made about the hypothesis of limiting fragmentation. In particular, the concept of favored and disfavored fragment distribution is introduced. Also, a sum rule is proved leading to a useful quantity called energy-fragmentation fraction. (author). 11 refs, 1 fig., 2 tabs
Multiple hypothesis clustering in radar plot extraction
Huizing, A.G.; Theil, A.; Dorp, Ph. van; Ligthart, L.P.
1995-01-01
False plots and plots with inaccurate range and Doppler estimates may severely degrade the performance of tracking algorithms in radar systems. This paper describes how a multiple hypothesis clustering technique can be applied to mitigate the problems involved in plot extraction. The measures of
The (not so immortal strand hypothesis
Directory of Open Access Journals (Sweden)
Cristian Tomasetti
2015-03-01
Significance: Utilizing an approach that is fundamentally different from previous efforts to confirm or refute the immortal strand hypothesis, we provide evidence against non-random segregation of DNA during stem cell replication. Our results strongly suggest that parental DNA is passed randomly to stem cell daughters and provides new insight into the mechanism of DNA replication in stem cells.
A Developmental Study of the Infrahumanization Hypothesis
Martin, John; Bennett, Mark; Murray, Wayne S.
2008-01-01
Intergroup attitudes in children were examined based on Leyen's "infrahumanization hypothesis". This suggests that some uniquely human emotions, such as shame and guilt (secondary emotions), are reserved for the in-group, whilst other emotions that are not uniquely human and shared with animals, such as anger and pleasure (primary…
Morbidity and Infant Development: A Hypothesis.
Pollitt, Ernesto
1983-01-01
Results of a study conducted in 14 villages of Sui Lin Township, Taiwan, suggest the hypothesis that, under conditions of extreme economic impoverishment and among children within populations where energy protein malnutrition is endemic, there is an inverse relationship between incidence of morbidity in infancy and measures of motor and mental…
Diagnostic Hypothesis Generation and Human Judgment
Thomas, Rick P.; Dougherty, Michael R.; Sprenger, Amber M.; Harbison, J. Isaiah
2008-01-01
Diagnostic hypothesis-generation processes are ubiquitous in human reasoning. For example, clinicians generate disease hypotheses to explain symptoms and help guide treatment, auditors generate hypotheses for identifying sources of accounting errors, and laypeople generate hypotheses to explain patterns of information (i.e., data) in the…
Multi-hypothesis distributed stereo video coding
DEFF Research Database (Denmark)
Salmistraro, Matteo; Zamarin, Marco; Forchhammer, Søren
2013-01-01
for stereo sequences, exploiting an interpolated intra-view SI and two inter-view SIs. The quality of the SI has a major impact on the DVC Rate-Distortion (RD) performance. As the inter-view SIs individually present lower RD performance compared with the intra-view SI, we propose multi-hypothesis decoding...
[Resonance hypothesis of heart rate variability origin].
Sheĭkh-Zade, Iu R; Mukhambetaliev, G Kh; Cherednik, I L
2009-09-01
A hypothesis is advanced of the heart rate variability being subjected to beat-to-beat regulation of cardiac cycle duration in order to ensure the resonance interaction between respiratory and own fluctuation of the arterial system volume for minimization of power expenses of cardiorespiratory system. Myogenic, parasympathetic and sympathetic machanisms of heart rate variability are described.
In Defense of Chi's Ontological Incompatibility Hypothesis
Slotta, James D.
2011-01-01
This article responds to an article by A. Gupta, D. Hammer, and E. F. Redish (2010) that asserts that M. T. H. Chi's (1992, 2005) hypothesis of an "ontological commitment" in conceptual development is fundamentally flawed. In this article, I argue that Chi's theoretical perspective is still very much intact and that the critique offered by Gupta…
Vacuum counterexamples to the cosmic censorship hypothesis
International Nuclear Information System (INIS)
Miller, B.D.
1981-01-01
In cylindrically symmetric vacuum spacetimes it is possible to specify nonsingular initial conditions such that timelike singularities will (necessarily) evolve from these conditions. Examples are given; the spacetimes are somewhat analogous to one of the spherically symmetric counterexamples to the cosmic censorship hypothesis
Maximizing percentage depletion in solid minerals
International Nuclear Information System (INIS)
Tripp, J.; Grove, H.D.; McGrath, M.
1982-01-01
This article develops a strategy for maximizing percentage depletion deductions when extracting uranium or other solid minerals. The goal is to avoid losing percentage depletion deductions by staying below the 50% limitation on taxable income from the property. The article is divided into two major sections. The first section is comprised of depletion calculations that illustrate the problem and corresponding solutions. The last section deals with the feasibility of applying the strategy and complying with the Internal Revenue Code and appropriate regulations. Three separate strategies or appropriate situations are developed and illustrated. 13 references, 3 figures, 7 tables
What currency do bumble bees maximize?
Directory of Open Access Journals (Sweden)
Nicholas L Charlton
2010-08-01
Full Text Available In modelling bumble bee foraging, net rate of energetic intake has been suggested as the appropriate currency. The foraging behaviour of honey bees is better predicted by using efficiency, the ratio of energetic gain to expenditure, as the currency. We re-analyse several studies of bumble bee foraging and show that efficiency is as good a currency as net rate in terms of predicting behaviour. We suggest that future studies of the foraging of bumble bees should be designed to distinguish between net rate and efficiency maximizing behaviour in an attempt to discover which is the more appropriate currency.
DEFF Research Database (Denmark)
Lisonek, Petr
1996-01-01
A two-distance set in E^d is a point set X inthe d-dimensional Euclidean spacesuch that the distances between distinct points in Xassume only two different non-zero values. Based on results from classical distance geometry, we developan algorithm to classify, for a given dimension, all maximal...... (largest possible)two-distance sets in E^d.Using this algorithm we have completed the full classificationfor all dimensions less than or equal to 7, andwe have found one set in E^8 whosemaximality follows from Blokhuis' upper bound on sizes of s-distance sets.While in the dimensions less than or equal to 6...
Maximizing policy learning in international committees
DEFF Research Database (Denmark)
Nedergaard, Peter
2007-01-01
, this article demonstrates that valuable lessons can be learned about policy learning, in practice and theoretically, by analysing the cooperation in the OMC committees. Using the Advocacy Coalition Framework as the starting point of analysis, 15 hypotheses on policy learning are tested. Among other things......, it is concluded that in order to maximize policy learning in international committees, empirical data should be made available to committees and provided by sources close to the participants (i.e. the Commission). In addition, the work in the committees should be made prestigious in order to attract well...
Pouliot type duality via a-maximization
International Nuclear Information System (INIS)
Kawano, Teruhiko; Ookouchi, Yutaka; Tachikawa, Yuji; Yagi, Futoshi
2006-01-01
We study four-dimensional N=1Spin(10) gauge theory with a single spinor and N Q vectors at the superconformal fixed point via the electric-magnetic duality and a-maximization. When gauge invariant chiral primary operators hit the unitarity bounds, we find that the theory with no superpotential is identical to the one with some superpotential at the infrared fixed point. The auxiliary field method in the electric theory offers a satisfying description of the infrared fixed point, which is consistent with the better picture in the magnetic theory. In particular, it gives a clear description of the emergence of new massless degrees of freedom in the electric theory
A novel hypothesis splitting method implementation for multi-hypothesis filters
DEFF Research Database (Denmark)
Bayramoglu, Enis; Ravn, Ole; Andersen, Nils Axel
2013-01-01
The paper presents a multi-hypothesis filter library featuring a novel method for splitting Gaussians into ones with smaller variances. The library is written in C++ for high performance and the source code is open and free1. The multi-hypothesis filters commonly approximate the distribution tran...
Kragten, N.; Rözer, J.
The income inequality hypothesis states that income inequality has a negative effect on individual’s health, partially because it reduces social trust. This article aims to critically assess the income inequality hypothesis by comparing several analytical strategies, namely OLS regression,
Cormie, Prue; McGuigan, Michael R; Newton, Robert U
2011-02-01
This series of reviews focuses on the most important neuromuscular function in many sport performances: the ability to generate maximal muscular power. Part 1, published in an earlier issue of Sports Medicine, focused on the factors that affect maximal power production while part 2 explores the practical application of these findings by reviewing the scientific literature relevant to the development of training programmes that most effectively enhance maximal power production. The ability to generate maximal power during complex motor skills is of paramount importance to successful athletic performance across many sports. A crucial issue faced by scientists and coaches is the development of effective and efficient training programmes that improve maximal power production in dynamic, multi-joint movements. Such training is referred to as 'power training' for the purposes of this review. Although further research is required in order to gain a deeper understanding of the optimal training techniques for maximizing power in complex, sports-specific movements and the precise mechanisms underlying adaptation, several key conclusions can be drawn from this review. First, a fundamental relationship exists between strength and power, which dictates that an individual cannot possess a high level of power without first being relatively strong. Thus, enhancing and maintaining maximal strength is essential when considering the long-term development of power. Second, consideration of movement pattern, load and velocity specificity is essential when designing power training programmes. Ballistic, plyometric and weightlifting exercises can be used effectively as primary exercises within a power training programme that enhances maximal power. The loads applied to these exercises will depend on the specific requirements of each particular sport and the type of movement being trained. The use of ballistic exercises with loads ranging from 0% to 50% of one-repetition maximum (1RM) and
Einstein's Revolutionary Light-Quantum Hypothesis
Stuewer, Roger H.
2005-05-01
The paper in which Albert Einstein proposed his light-quantum hypothesis was the only one of his great papers of 1905 that he himself termed ``revolutionary.'' Contrary to widespread belief, Einstein did not propose his light-quantum hypothesis ``to explain the photoelectric effect.'' Instead, he based his argument for light quanta on the statistical interpretation of the second law of thermodynamics, with the photoelectric effect being only one of three phenomena that he offered as possible experimental support for it. I will discuss Einstein's light-quantum hypothesis of 1905 and his introduction of the wave-particle duality in 1909 and then turn to the reception of his work on light quanta by his contemporaries. We will examine the reasons that prominent physicists advanced to reject Einstein's light-quantum hypothesis in succeeding years. Those physicists included Robert A. Millikan, even though he provided convincing experimental proof of the validity of Einstein's equation of the photoelectric effect in 1915. The turning point came after Arthur Holly Compton discovered the Compton effect in late 1922, but even then Compton's discovery was contested both on experimental and on theoretical grounds. Niels Bohr, in particular, had never accepted the reality of light quanta and now, in 1924, proposed a theory, the Bohr-Kramers-Slater theory, which assumed that energy and momentum were conserved only statistically in microscopic interactions. Only after that theory was disproved experimentally in 1925 was Einstein's revolutionary light-quantum hypothesis generally accepted by physicists---a full two decades after Einstein had proposed it.
A Dopamine Hypothesis of Autism Spectrum Disorder.
Pavăl, Denis
2017-01-01
Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders characterized by social deficits and stereotyped behaviors. While several theories have emerged, the pathogenesis of ASD remains unknown. Although studies report dopamine signaling abnormalities in autistic patients, a coherent dopamine hypothesis which could link neurobiology to behavior in ASD is currently lacking. In this paper, we present such a hypothesis by proposing that autistic behavior arises from dysfunctions in the midbrain dopaminergic system. We hypothesize that a dysfunction of the mesocorticolimbic circuit leads to social deficits, while a dysfunction of the nigrostriatal circuit leads to stereotyped behaviors. Furthermore, we discuss 2 key predictions of our hypothesis, with emphasis on clinical and therapeutic aspects. First, we argue that dopaminergic dysfunctions in the same circuits should associate with autistic-like behavior in nonautistic subjects. Concerning this, we discuss the case of PANDAS (pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections) which displays behaviors similar to those of ASD, presumed to arise from dopaminergic dysfunctions. Second, we argue that providing dopamine modulators to autistic subjects should lead to a behavioral improvement. Regarding this, we present clinical studies of dopamine antagonists which seem to have improving effects on autistic behavior. Furthermore, we explore the means of testing our hypothesis by using neuroreceptor imaging, which could provide comprehensive evidence for dopamine signaling dysfunctions in autistic subjects. Lastly, we discuss the limitations of our hypothesis. Along these lines, we aim to provide a dopaminergic model of ASD which might lead to a better understanding of the ASD pathogenesis. © 2017 S. Karger AG, Basel.
Maximization techniques for oilfield development profits
International Nuclear Information System (INIS)
Lerche, I.
1999-01-01
In 1981 Nind provided a quantitative procedure for estimating the optimum number of development wells to emplace on an oilfield to maximize profit. Nind's treatment assumed that there was a steady selling price, that all wells were placed in production simultaneously, and that each well's production profile was identical and a simple exponential decline with time. This paper lifts these restrictions to allow for price fluctuations, variable with time emplacement of wells, and production rates that are more in line with actual production records than is a simple exponential decline curve. As a consequence, it is possible to design production rate strategies, correlated with price fluctuations, so as to maximize the present-day worth of a field. For price fluctuations that occur on a time-scale rapid compared to inflation rates it is appropriate to have production rates correlate directly with such price fluctuations. The same strategy does not apply for price fluctuations occurring on a time-scale long compared to inflation rates where, for small amplitudes in the price fluctuations, it is best to sell as much product as early as possible to overcome inflation factors, while for large amplitude fluctuations the best strategy is to sell product as early as possible but to do so mainly on price upswings. Examples are provided to show how these generalizations of Nind's (1981) formula change the complexion of oilfield development optimization. (author)
Directory of Open Access Journals (Sweden)
Nicoletta Zanni
2014-04-01
Full Text Available Dopo un breve excursus sui caratteri dell’ urbanistica neoclassica di Trieste, ci si concentra sull’apporto di alcuni dei protagonisti della progettazione architettonica, tra fine Settecento e prima metà dell’Ottocento, e sui principali edifici pubblici e privati edificati (Borsa, Teatro, chiese, ospedale, palazzi e palazzetti che hanno dato risalto all’omogeneità visiva dell’imprinting neoclassico: espressione di una classe emergente che associa l’utilità al decoro, ma non indulge all’ostentazione e agli sprechi, la nuova borghesia dei commerci marittimi. Quella stessa alta borghesia cresce per dimensioni e attività finanziarie e poi innesta lo sviluppo storicistico ed eclettico della Trieste borghese del secondo Ottocento, non trascurando però l’aspetto neoclassico che coinvolge in nuove dimensioni. After a brief excursus on the characters of the Neoclassical town planning in Trieste, the author analyzes the contribution of the main architects who were there active between the second half of the 18th century and the first half of the 19th century. The attention is paid to the main public and private buildings (the Stock Exchange, the Theatre, the churches, the Hospital, the palaces and the houses. All of them gave a sort of visual homogeneity of the Neoclassical imprinting; they are expression of an emergent class that lies utility to decorum, but does not cease to the ostentation and wastes: the new bourgeois class of commerce. In the second half of the 19th century, this same bourgeois class enlarges its financial activities and gives beginning to the Eclecticism and Historismus, without forgetting the Neoclassical aspects in a new large dimension.
Directory of Open Access Journals (Sweden)
Wei-Bin ZHANG
2017-06-01
Full Text Available This paper proposes a two-sector two-group growth model with elastic labor supply and consumer durable goods. We study dynamics of wealth and income distribution in a competitive economy with capital accumulation as the main engine of economic growth. The model is built on the Uzawa two-sector model. It is also influenced by the neoclassical growth theory and the post-Keynesian theory of growth and distribution. We plot the motion of the economic system and determine the economic equilibrium. We carry out comparative dynamic analysis with regard to the propensity to save and improvements in human capital and technology.
Testing the activitystat hypothesis: a randomised controlled trial protocol.
Gomersall, Sjaan; Maher, Carol; Norton, Kevin; Dollman, Jim; Tomkinson, Grant; Esterman, Adrian; English, Coralie; Lewis, Nicole; Olds, Tim
2012-10-08
The activitystat hypothesis proposes that when physical activity or energy expenditure is increased or decreased in one domain, there will be a compensatory change in another domain to maintain an overall, stable level of physical activity or energy expenditure. To date, there has been no experimental study primarily designed to test the activitystat hypothesis in adults. The aim of this trial is to determine the effect of two different imposed exercise loads on total daily energy expenditure and physical activity levels. This study will be a randomised, multi-arm, parallel controlled trial. Insufficiently active adults (as determined by the Active Australia survey) aged 18-60 years old will be recruited for this study (n=146). Participants must also satisfy the Sports Medicine Australia Pre-Exercise Screening System and must weigh less than 150 kg. Participants will be randomly assigned to one of three groups using a computer-generated allocation sequence. Participants in the Moderate exercise group will receive an additional 150 minutes of moderate to vigorous physical activity per week for six weeks, and those in the Extensive exercise group will receive an additional 300 minutes of moderate to vigorous physical activity per week for six weeks. Exercise targets will be accumulated through both group and individual exercise sessions monitored by heart rate telemetry. Control participants will not be given any instructions regarding lifestyle. The primary outcome measures are activity energy expenditure (doubly labeled water) and physical activity (accelerometry). Secondary measures will include resting metabolic rate via indirect calorimetry, use of time, maximal oxygen consumption and several anthropometric and physiological measures. Outcome measures will be conducted at baseline (zero weeks), mid- and end-intervention (three and six weeks) with three (12 weeks) and six month (24 week) follow-up. All assessors will be blinded to group allocation. This protocol