Nonlinear vibrations of functionally graded doubly curved shallow shells
NASA Astrophysics Data System (ADS)
Alijani, F.; Amabili, M.; Karagiozis, K.; Bakhtiari-Nejad, F.
2011-03-01
Nonlinear forced vibrations of FGM doubly curved shallow shells with a rectangular base are investigated. Donnell's nonlinear shallow-shell theory is used and the shell is assumed to be simply supported with movable edges. The equations of motion are reduced using the Galerkin method to a system of infinite nonlinear ordinary differential equations with quadratic and cubic nonlinearities. Using the multiple scales method, primary and subharmonic resonance responses of FGM shells are fully discussed and the effect of volume fraction exponent on the internal resonance conditions, softening/hardening behavior and bifurcations of the shallow shell when the excitation frequency is (i) near the fundamental frequency and (ii) near two times the fundamental frequency is shown. Moreover, using a code based on arclength continuation method, a bifurcation analysis is carried out for a special case with two-to-one internal resonance between the first and second doubly symmetric modes with respect to the panel's center ( ω13≈2 ω11). Bifurcation diagrams and Poincaré maps are obtained through direct time integration of the equations of motion and chaotic regions are shown by calculating Lyapunov exponents and Lyapunov dimension.
Optomechanical Enhancement of Doubly Resonant 2D Optical Nonlinearity.
Yi, Fei; Ren, Mingliang; Reed, Jason C; Zhu, Hai; Hou, Jiechang; Naylor, Carl H; Johnson, A T Charlie; Agarwal, Ritesh; Cubukcu, Ertugrul
2016-03-01
Emerging two-dimensional semiconductor materials possess a giant second order nonlinear response due to excitonic effects while the monolayer thickness of such active materials limits their use in practical nonlinear devices. Here, we report 3300 times optomechanical enhancement of second harmonic generation from a MoS2 monolayer in a doubly resonant on-chip optical cavity. We achieve this by engineering the nonlinear light-matter interaction in a microelectro-mechanical system enabled optical frequency doubling device based on an electrostatically tunable Fabry-Perot microresonator. Our versatile optomechanical approach will pave the way for next generation efficient on-chip tunable light sources, sensors, and systems based on molecularly thin materials. PMID:26854706
Optomechanical Enhancement of Doubly Resonant 2D Optical Nonlinearity.
Yi, Fei; Ren, Mingliang; Reed, Jason C; Zhu, Hai; Hou, Jiechang; Naylor, Carl H; Johnson, A T Charlie; Agarwal, Ritesh; Cubukcu, Ertugrul
2016-03-01
Emerging two-dimensional semiconductor materials possess a giant second order nonlinear response due to excitonic effects while the monolayer thickness of such active materials limits their use in practical nonlinear devices. Here, we report 3300 times optomechanical enhancement of second harmonic generation from a MoS2 monolayer in a doubly resonant on-chip optical cavity. We achieve this by engineering the nonlinear light-matter interaction in a microelectro-mechanical system enabled optical frequency doubling device based on an electrostatically tunable Fabry-Perot microresonator. Our versatile optomechanical approach will pave the way for next generation efficient on-chip tunable light sources, sensors, and systems based on molecularly thin materials.
Nonsnaking doubly diffusive convectons and the twist instability
Beaume, Cédric Knobloch, Edgar; Bergeon, Alain
2013-11-15
Doubly diffusive convection in a three-dimensional horizontally extended domain with a square cross section in the vertical is considered. The fluid motion is driven by horizontal temperature and concentration differences in the transverse direction. When the buoyancy ratio N = −1 and the Rayleigh number is increased the conduction state loses stability to a subcritical, almost two-dimensional roll structure localized in the longitudinal direction. This structure exhibits abrupt growth in length near a particular value of the Rayleigh number but does not snake. Prior to this filling transition the structure becomes unstable to a secondary twist instability generating a pair of stationary, spatially localized zigzag states. In contrast to the primary branch these states snake as they grow in extent and eventually fill the whole domain. The origin of the twist instability and the properties of the resulting localized structures are investigated for both periodic and no-slip boundary conditions in the extended direction.
Nonlinear diffusion and superconducting hysteresis
Mayergoyz, I.D.
1996-12-31
Nonlinear diffusion of electromagnetic fields in superconductors with ideal and gradual resistive transitions is studied. Analytical results obtained for linear and nonlinear polarizations of electromagnetic fields are reported. These results lead to various extensions of the critical state model for superconducting hysteresis.
Nonlinear Diffusion and Transient Osmosis
NASA Astrophysics Data System (ADS)
Akira, Igarashi; Lamberto, Rondoni; Antonio, Botrugno; Marco, Pizzi
2011-08-01
We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call “transient osmosis". We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes.
Unconventional photon blockade in doubly resonant microcavities with second-order nonlinearity
NASA Astrophysics Data System (ADS)
Gerace, Dario; Savona, Vincenzo
2014-03-01
It is shown that noncentrosymmetric materials with bulk second-order nonlinear susceptibility can be used to generate strongly antibunched radiation at an arbitrary wavelength, solely determined by the resonant behavior of suitably engineered coupled microcavities. The proposed scheme exploits the unconventional photon blockade of a coherent driving field at the input of a coupled cavity system, where one of the two cavities is engineered to resonate at both fundamental and second harmonic frequencies, respectively. Remarkably, the unconventional blockade mechanism occurs with reasonably low quality factors at both harmonics, and does not require a sharp doubly resonant condition for the second cavity, thus proving its feasibility with current semiconductor technology.
Stabilization of the solution of a doubly nonlinear parabolic equation
Andriyanova, È R; Mukminov, F Kh
2013-09-30
The method of Galerkin approximations is employed to prove the existence of a strong global (in time) solution of a doubly nonlinear parabolic equation in an unbounded domain. The second integral identity is established for Galerkin approximations, and passing to the limit in it an estimate for the decay rate of the norm of the solution from below is obtained. The estimates characterizing the decay rate of the solution as x→∞ obtained here are used to derive an upper bound for the decay rate of the solution with respect to time; the resulting estimate is pretty close to the lower one. Bibliography: 17 titles.
Gabor-based kernel PCA with doubly nonlinear mapping for face recognition with a single face image.
Xie, Xudong; Lam, Kin-Man
2006-09-01
In this paper, a novel Gabor-based kernel principal component analysis (PCA) with doubly nonlinear mapping is proposed for human face recognition. In our approach, the Gabor wavelets are used to extract facial features, then a doubly nonlinear mapping kernel PCA (DKPCA) is proposed to perform feature transformation and face recognition. The conventional kernel PCA nonlinearly maps an input image into a high-dimensional feature space in order to make the mapped features linearly separable. However, this method does not consider the structural characteristics of the face images, and it is difficult to determine which nonlinear mapping is more effective for face recognition. In this paper, a new method of nonlinear mapping, which is performed in the original feature space, is defined. The proposed nonlinear mapping not only considers the statistical property of the input features, but also adopts an eigenmask to emphasize those important facial feature points. Therefore, after this mapping, the transformed features have a higher discriminating power, and the relative importance of the features adapts to the spatial importance of the face images. This new nonlinear mapping is combined with the conventional kernel PCA to be called "doubly" nonlinear mapping kernel PCA. The proposed algorithm is evaluated based on the Yale database, the AR database, the ORL database and the YaleB database by using different face recognition methods such as PCA, Gabor wavelets plus PCA, and Gabor wavelets plus kernel PCA with fractional power polynomial models. Experiments show that consistent and promising results are obtained.
Compact waves in microscopic nonlinear diffusion.
Hurtado, P I; Krapivsky, P L
2012-06-01
We analyze the spread of a localized peak of energy into vacuum for nonlinear diffusive processes. In contrast with standard diffusion, the nonlinearity results in a compact wave with a sharp front separating the perturbed region from vacuum. In d spatial dimensions, the front advances as t^{1/(2+da)} according to hydrodynamics, with a the nonlinearity exponent. We show that fluctuations in the front position grow as ∼t^{μ}η, where μ<1/2+da is an exponent that we measure and η is a random variable whose distribution we characterize. Fluctuating corrections to hydrodynamic profiles give rise to an excess penetration into vacuum, revealing scaling behaviors and robust features. We also examine the discharge of a nonlinear rarefaction wave into vacuum. Our results suggest the existence of universal scaling behaviors at the fluctuating level in nonlinear diffusion.
Turing instability in reaction-diffusion systems with nonlinear diffusion
NASA Astrophysics Data System (ADS)
Zemskov, E. P.
2013-10-01
The Turing instability is studied in two-component reaction-diffusion systems with nonlinear diffusion terms, and the regions in parametric space where Turing patterns can form are determined. The boundaries between super- and subcritical bifurcations are found. Calculations are performed for one-dimensional brusselator and oregonator models.
Turing instability in reaction-diffusion systems with nonlinear diffusion
Zemskov, E. P.
2013-10-15
The Turing instability is studied in two-component reaction-diffusion systems with nonlinear diffusion terms, and the regions in parametric space where Turing patterns can form are determined. The boundaries between super- and subcritical bifurcations are found. Calculations are performed for one-dimensional brusselator and oregonator models.
Nonlinear diffusion filtering influenced by mean curvature
NASA Astrophysics Data System (ADS)
Kollár, Michal; Mikula, Karol; Čunderlík, Róbert
2016-04-01
The presentation introduces a new nonlinear diffusion filtering method on closed surfaces such as a sphere, ellipsoid or the Earth's surface. Our new model extends the regularized surface Perona-Malik model by including a local extrema detector based on a mean curvature of processed data. The model is thus represented by a nonlinear diffusion equation which filters noise while preserves main edges, local extrema and details important for a correct interpretation of data. We define a surface finite-volume method to approximate numerically the nonlinear parabolic partial differential equation on a closed surface. The closed surface is approximated by a polyhedral surface created by planar triangles representing subdivision of an initial icosahedron grid and we use a piece-wise linear approximation of a solution in space and the backward Euler time discretization. Numerical experiments present nonlinear diffusion filtering of artificial data and real measurements, namely the GOCE satellite observations. They aim to point out a main advantage of the new nonlinear model which, on the contrary of Perona-Malik model, preserves local extremal values of filtered data.
Hall, Matt G; Bongers, Andre; Sved, Paul; Watson, Geoffrey; Bourne, Roger M
2015-04-01
Non-Gaussian diffusion dynamics was investigated in the two distinct water populations identified by a biexponential model of diffusion in prostate tissue. Diffusion-weighted MRI (DWI) signal attenuation was measured ex vivo in two formalin-fixed prostates at 9.4 T with diffusion times Δ = 10, 20 and 40 ms, and b values in the range 0.017-8.2 ms/µm(2) . A conventional biexponential model was compared with models in which either the lower diffusivity component or both of the components of the biexponential were stretched. Models were compared using Akaike's Information Criterion (AIC) and a leave-one-out (LOO) test of model prediction accuracy. The doubly stretched (SS) model had the highest LOO prediction accuracy and lowest AIC (highest information content) in the majority of voxels at Δ = 10 and 20 ms. The lower diffusivity stretching factor (α2 ) of the SS model was consistently lower (range ~0.3-0.9) than the higher diffusivity stretching factor (α1 , range ~0.7-1.1), indicating a high degree of diffusion heterogeneity in the lower diffusivity environment, and nearly Gaussian diffusion in the higher diffusivity environment. Stretched biexponential models demonstrate that, in prostate tissue, the two distinct water populations identified by the simple biexponential model individually exhibit non-Gaussian diffusion dynamics.
Contrast Enhancement by Nonlinear Diffusion Filtering.
Liang, Zhetong; Liu, Weijian; Yao, Ruohe
2016-02-01
To enhance the visual quality of an image that is degraded by uneven light, an effective method is to estimate the illumination component and compress it. Some previous methods have either defects of halo artifacts or contrast loss in the enhanced image due to incorrect estimation. In this paper, we discuss this problem and propose a novel method to estimate the illumination. The illumination is obtained by iteratively solving a nonlinear diffusion equation. During the diffusion process, surround suppression is embedded in the conductance function to specially enhance the diffusive strength in textural areas of the image. The proposed estimation method has the following two merits: 1) the boundary areas are preserved in the illumination, and thus halo artifacts are prevented and 2) the textural details are preserved in the reflectance to not suffer from illumination compression, which contributes to the contrast enhancement in the result. Experimental results show that the proposed algorithm achieves excellent performance in artifact removal and local contrast enhancement. PMID:26685234
Solution spectrum of nonlinear diffusion equations
Ulmer, W.
1992-08-01
The stationary version of the nonlinear diffusion equation -{partial_derivative}c/{partial_derivative}t+D{Delta}c=A{sub 1}c-A{sub 2}c{sup 2} can be solved with the ansatz c={summation}{sub p=1}{sup {infinity}} A{sub p}(cosh kx){sup -p}, inducing a band structure with regard to the ratio {lambda}{sub 1}/{lambda}{sub 2}. The resulting solution manifold can be related to an equilibrium of fluxes of nonequilibrium thermodynamics. The modification of this ansatz yielding the expansion c={summation}{sub p,q=1}{sup infinity}A{sub pa}(cosh kx){sup -p}[(cosh {alpha}t){sup -q-1} sinh {alpha}t+b(cosh {alpha}t){sup -q}] represents a solution spectrum of the time-dependent nonlinear equations, and the stationary version can be found from the asymptotic behaviour of the expansion. The solutions can be associated with reactive processes such as active transport phenomena and control circuit problems is discussed. There are also applications to cellular kinetics of clonogenic cell assays and spheriods. 33 refs., 1 tab.
Nonlinear diffusivity of analytes in tissues
NASA Astrophysics Data System (ADS)
Ghosn, Mohamad G.; Carbajal, Esteban F.; Befrui, Natasha A.; Tuchin, Valery V.; Larin, Kirill V.
2008-02-01
Noninvasive assessments of optical clearing and permeability coefficients of tissues pose great possibilities in advanced diagnostics and medical applications. In order for both of these to become utilized in common practice, a greater understanding of molecular diffusivity in multi-layered tissues is required. In biological tissues, the different layers are comprised of differentiated cells and/or collagen fibrils which come together to form that specific layer. Therefore, a patchwork of layers is created each with its own set of properties. In our current study we analyze and describe the dynamics of matter diffusion and its underlying non-linear character in various epithelial tissues. For instance, the permeability coefficient (PC) of 20% concentrated mannitol in the rabbit eye sclera showed an increasing trend as it was measured deeper into the tissue. The PC was found to be 2.18 × 10 -6 cm/sec at 50 μm away from the epithelial layer. It increased to about 7.33 × 10 -6 cm/sec when it was computed at 210 μm from the epithelial layer. Different layers in the sclera showed different clearing response to glucose solution as well. The first 100 μm region from the epithelial layer cleared about 10% whereas the next 100 μm cleared about 17-22%. The importance of this study is that it may offer a novel explanation to how a layer's composition affects optical clearing and the permeability coefficient of analytes and solutions.
Nonlinear mode interactions and frequency-jump effects in a doubly tuned oscillator configuration
NASA Astrophysics Data System (ADS)
Grun, J.; Lashinsky, H.
1980-05-01
Frequency-jump effects associated with nonlinear mode competition are investigated in an oscillator configuration consisting of a passive linear resonance system coupled to an active nonlinear resonance system. These effects give rise to a hysteresis pattern whose height and width can be related to system parameters such as the resonance frequencies, dissipation, coupling coefficient, etc. It is noted that these effects offer a novel means of determining these parameters in cases in which conventional techniques may not be desirable or as advantageous. The analysis provides an qualitative explanation of empirical observations in a recent nuclear magnetic resonance experiment (Timsit and Daniels, 1976). The results also apply to other nonlinear resonance systems such as lasers, microwave generators, and electronic oscillators.
Lattice Boltzmann model for nonlinear convection-diffusion equations.
Shi, Baochang; Guo, Zhaoli
2009-01-01
A lattice Boltzmann model for convection-diffusion equation with nonlinear convection and isotropic-diffusion terms is proposed through selecting equilibrium distribution function properly. The model can be applied to the common real and complex-valued nonlinear evolutionary equations, such as the nonlinear Schrödinger equation, complex Ginzburg-Landau equation, Burgers-Fisher equation, nonlinear heat conduction equation, and sine-Gordon equation, by using a real and complex-valued distribution function and relaxation time. Detailed simulations of these equations are performed, and it is found that the numerical results agree well with the analytical solutions and the numerical solutions reported in previous studies.
Optical surface wave in a crystal with diffusion photorefractive nonlinearity
Chetkin, S A; Akhmedzhanov, I M
2011-11-30
We consider a steady-state nonlinear photorefractive surface wave (PR SW) with TE or TM polarisation when the refractive index of the photorefractive crystal (PRC) depends on the strength of the diffusion crystal electric field emerging upon the wave propagation. We have determined the phase trajectory and transverse structure of the PR SW intensity distribution for different values of the diffusion photorefractive nonlinearity. We have investigated a photorefractive diffraction grating, which arises in the surface PRC layer during propagation of the nonlinear PR SW.
Groundwater transport modeling with nonlinear sorption and intraparticle diffusion
NASA Astrophysics Data System (ADS)
Singh, Anshuman; Allen-King, Richelle M.; Rabideau, Alan J.
2014-08-01
Despite recent advances in the mechanistic understanding of sorption in groundwater systems, most contaminant transport models provide limited support for nonideal sorption processes such as nonlinear isotherms and/or diffusion-limited sorption. However, recent developments in the conceptualization of "dual mode" sorption for hydrophobic organic contaminants have provided more realistic and mechanistically sound alternatives to the commonly used Langmuir and Freundlich models. To support the inclusion of both nonlinear and diffusion-limited sorption processes in groundwater transport models, this paper presents two numerical algorithms based on the split operator approach. For the nonlinear equilibrium scenario, the commonly used two-step split operator algorithm has been modified to provide a more robust treatment of complex multi-parameter isotherms such as the Polanyi-partitioning model. For diffusion-limited sorption, a flexible three step split-operator procedure is presented to simulate intraparticle diffusion in multiple spherical particles with different sizes and nonlinear isotherms. Numerical experiments confirmed the accuracy of both algorithms for several candidate isotherms. However, the primary advantages of the algorithms are: (1) flexibility to accommodate any isotherm equation including "dual mode" and similar expressions, and (2) ease of adapting existing grid-based transport models of any dimensionality to include nonlinear sorption and/or intraparticle diffusion. Comparisons are developed for one-dimensional transport scenarios with different isotherms and particle configurations. Illustrative results highlight (1) the potential influence of isotherm model selection on solute transport predictions, and (2) the combined effects of intraparticle diffusion and nonlinear sorption on the plume transport and flushing for both single-particle and multi-particle scenarios.
The thermal stability of coronal loops by nonlinear diffusion asymptotics
NASA Technical Reports Server (NTRS)
Pakkert, J. W.; Verhulst, F.; Martens, P. C. H.
1987-01-01
A nonlinear reaction-diffusion equation and some additional constraints are derived which describe the time-dependent behavior of the temperature structure of the plasma in coronal loops. The equation is analyzed using nonlinear diffusion asymptotics, in particular singular perturbation techniques, and the results are interpreted in the context of the physical problem of the thermal stability and temporal behavior of the plasma. The results are consistent with the possibility of cyclic thermal behavior of the plasma, as suggested by Kuin and Martens (1982).
Fluorescence Correlation Spectroscopy and Nonlinear Stochastic Reaction-Diffusion
Del Razo, Mauricio; Pan, Wenxiao; Qian, Hong; Lin, Guang
2014-05-30
The currently existing theory of fluorescence correlation spectroscopy (FCS) is based on the linear fluctuation theory originally developed by Einstein, Onsager, Lax, and others as a phenomenological approach to equilibrium fluctuations in bulk solutions. For mesoscopic reaction-diffusion systems with nonlinear chemical reactions among a small number of molecules, a situation often encountered in single-cell biochemistry, it is expected that FCS time correlation functions of a reaction-diffusion system can deviate from the classic results of Elson and Magde [Biopolymers (1974) 13:1-27]. We first discuss this nonlinear effect for reaction systems without diffusion. For nonlinear stochastic reaction-diffusion systems there are no closed solutions; therefore, stochastic Monte-Carlo simulations are carried out. We show that the deviation is small for a simple bimolecular reaction; the most significant deviations occur when the number of molecules is small and of the same order. Extending Delbrück-Gillespie’s theory for stochastic nonlinear reactions with rapidly stirring to reaction-diffusion systems provides a mesoscopic model for chemical and biochemical reactions at nanometric and mesoscopic level such as a single biological cell.
Transitory behaviors in diffusively coupled nonlinear oscillators.
Tadokoro, Satoru; Yamaguti, Yutaka; Fujii, Hiroshi; Tsuda, Ichiro
2011-03-01
We study collective behaviors of diffusively coupled oscillators which exhibit out-of-phase synchrony for the case of weakly interacting two oscillators. In large populations of such oscillators interacting via one-dimensionally nearest neighbor couplings, there appear various collective behaviors depending on the coupling strength, regardless of the number of oscillators. Among others, we focus on an intermittent behavior consisting of the all-synchronized state, a weakly chaotic state and some sorts of metachronal waves. Here, a metachronal wave means a wave with orderly phase shifts of oscillations. Such phase shifts are produced by the dephasing interaction which produces the out-of-phase synchronized states in two coupled oscillators. We also show that the abovementioned intermittent behavior can be interpreted as in-out intermittency where two saddles on an invariant subspace, the all-synchronized state and one of the metachronal waves play an important role.
Boundedness in a chemotaxis-haptotaxis model with nonlinear diffusion
NASA Astrophysics Data System (ADS)
Li, Yan; Lankeit, Johannes
2016-05-01
This article deals with an initial-boundary value problem for the coupled chemotaxis-haptotaxis system with nonlinear diffusion under homogeneous Neumann boundary conditions in a bounded smooth domain Ω \\subset {{{R}}n} , n = 2, 3, 4, where χ,ξ and μ are given nonnegative parameters. The diffusivity D(u) is assumed to satisfy D(u)≥slant δ {{u}m-1} for all u > 0 with some δ >0 . It is proved that for sufficiently regular initial data global bounded solutions exist whenever m>2-\\frac{2}{n} . For the case of non-degenerate diffusion (i.e. D(0) > 0) the solutions are classical; for the case of possibly degenerate diffusion (D(0)≥slant 0 ), the existence of bounded weak solutions is shown.
Diffusive limits of nonlinear hyperbolic systems with variable coefficients
NASA Astrophysics Data System (ADS)
Miyoshi, Hironari; Tsutsumi, Masayoshi
2016-09-01
We consider the initial-boundary value problem for a 2-speed system of first-order nonhomogeneous semilinear hyperbolic equations whose leading terms have a small positive parameter. Using energy estimates and a compactness lemma, we show that the diffusion limit of the sum of the solutions of the hyperbolic system, as the parameter tends to zero, verifies the nonlinear parabolic equation of the p-Laplacian type.
Nonlinear diffusion model for Rayleigh-Taylor mixing.
Boffetta, G; De Lillo, F; Musacchio, S
2010-01-22
The complex evolution of turbulent mixing in Rayleigh-Taylor convection is studied in terms of eddy diffusivity models for the mean temperature profile. It is found that a nonlinear model, derived within the general framework of Prandtl mixing theory, reproduces accurately the evolution of turbulent profiles obtained from numerical simulations. Our model allows us to give very precise predictions for the turbulent heat flux and for the Nusselt number in the ultimate state regime of thermal convection.
Turing pattern formation in the Brusselator system with nonlinear diffusion.
Gambino, G; Lombardo, M C; Sammartino, M; Sciacca, V
2013-10-01
In this work we investigate the effect of density-dependent nonlinear diffusion on pattern formation in the Brusselator system. Through linear stability analysis of the basic solution we determine the Turing and the oscillatory instability boundaries. A comparison with the classical linear diffusion shows how nonlinear diffusion favors the occurrence of Turing pattern formation. We study the process of pattern formation both in one-dimensional and two-dimensional spatial domains. Through a weakly nonlinear multiple scales analysis we derive the equations for the amplitude of the stationary patterns. The analysis of the amplitude equations shows the occurrence of a number of different phenomena, including stable supercritical and subcritical Turing patterns with multiple branches of stable solutions leading to hysteresis. Moreover, we consider traveling patterning waves: When the domain size is large, the pattern forms sequentially and traveling wave fronts are the precursors to patterning. We derive the Ginzburg-Landau equation and describe the traveling front enveloping a pattern which invades the domain. We show the emergence of radially symmetric target patterns, and, through a matching procedure, we construct the outer amplitude equation and the inner core solution. PMID:24229267
Turing pattern formation in the Brusselator system with nonlinear diffusion
NASA Astrophysics Data System (ADS)
Gambino, G.; Lombardo, M. C.; Sammartino, M.; Sciacca, V.
2013-10-01
In this work we investigate the effect of density-dependent nonlinear diffusion on pattern formation in the Brusselator system. Through linear stability analysis of the basic solution we determine the Turing and the oscillatory instability boundaries. A comparison with the classical linear diffusion shows how nonlinear diffusion favors the occurrence of Turing pattern formation. We study the process of pattern formation both in one-dimensional and two-dimensional spatial domains. Through a weakly nonlinear multiple scales analysis we derive the equations for the amplitude of the stationary patterns. The analysis of the amplitude equations shows the occurrence of a number of different phenomena, including stable supercritical and subcritical Turing patterns with multiple branches of stable solutions leading to hysteresis. Moreover, we consider traveling patterning waves: When the domain size is large, the pattern forms sequentially and traveling wave fronts are the precursors to patterning. We derive the Ginzburg-Landau equation and describe the traveling front enveloping a pattern which invades the domain. We show the emergence of radially symmetric target patterns, and, through a matching procedure, we construct the outer amplitude equation and the inner core solution.
NASA Astrophysics Data System (ADS)
Cherniha, Roman; King, John R.; Kovalenko, Sergii
2016-07-01
Complete descriptions of the Lie symmetries of a class of nonlinear reaction-diffusion equations with gradient-dependent diffusivity in one and two space dimensions are obtained. A surprisingly rich set of Lie symmetry algebras depending on the form of diffusivity and source (sink) in the equations is derived. It is established that there exists a subclass in 1-D space admitting an infinite-dimensional Lie algebra of invariance so that it is linearisable. A special power-law diffusivity with a fixed exponent, which leads to wider Lie invariance of the equations in question in 2-D space, is also derived. However, it is shown that the diffusion equation without a source term (which often arises in applications and is sometimes called the Perona-Malik equation) possesses no rich variety of Lie symmetries depending on the form of gradient-dependent diffusivity. The results of the Lie symmetry classification for the reduction to lower dimensionality, and a search for exact solutions of the nonlinear 2-D equation with power-law diffusivity, also are included.
NASA Astrophysics Data System (ADS)
Wei, Song; Chen, Wen; Hon, Y. C.
2016-11-01
This paper investigates the temporal effects in the modeling of flows through porous media and particles transport. Studies will be made among the time fractional diffusion model and two classical nonlinear diffusion models. The effects of the parameters upon the mentioned models have been studied. By simulating the sub-diffusion processes and comparing the numerical results of these models under different boundary conditions, we can conclude that the time fractional diffusion model is more suitable for simulating the sub-diffusion with steady diffusion rate; whereas the nonlinear models are more appropriate for depicting the sub-diffusion under changing diffusion rate.
NASA Astrophysics Data System (ADS)
Liu, Hanze
2016-07-01
In this paper, the combination of generalized symmetry classification and recursion operator method is developed for dealing with nonlinear diffusion equations (NLDEs). Through the combination approach, all of the second and third-order generalized symmetries of the general nonlinear diffusion equation are obtained. As its special case, the recursion operators of the nonlinear heat conduction equation are constructed, and the integrable properties of the nonlinear equations are considered. Furthermore, the exact and explicit solutions generated from the generalized symmetries are investigated.
Nonlinear diffusion equations as asymptotic limits of Cahn-Hilliard systems
NASA Astrophysics Data System (ADS)
Colli, Pierluigi; Fukao, Takeshi
2016-05-01
An asymptotic limit of a class of Cahn-Hilliard systems is investigated to obtain a general nonlinear diffusion equation. The target diffusion equation may reproduce a number of well-known model equations: Stefan problem, porous media equation, Hele-Shaw profile, nonlinear diffusion of singular logarithmic type, nonlinear diffusion of Penrose-Fife type, fast diffusion equation and so on. Namely, by setting the suitable potential of the Cahn-Hilliard systems, all these problems can be obtained as limits of the Cahn-Hilliard related problems. Convergence results and error estimates are proved.
New variable separation solutions for the generalized nonlinear diffusion equations
NASA Astrophysics Data System (ADS)
Fei-Yu, Ji; Shun-Li, Zhang
2016-03-01
The functionally generalized variable separation of the generalized nonlinear diffusion equations ut = A(u,ux)uxx + B(u,ux) is studied by using the conditional Lie-Bäcklund symmetry method. The variant forms of the considered equations, which admit the corresponding conditional Lie-Bäcklund symmetries, are characterized. To construct functionally generalized separable solutions, several concrete examples defined on the exponential and trigonometric invariant subspaces are provided. Project supported by the National Natural Science Foundation of China (Grant Nos. 11371293, 11401458, and 11501438), the National Natural Science Foundation of China, Tian Yuan Special Foundation (Grant No. 11426169), and the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2015JQ1014).
Geometrically nonlinear continuum thermomechanics with surface energies coupled to diffusion
NASA Astrophysics Data System (ADS)
McBride, A. T.; Javili, A.; Steinmann, P.; Bargmann, S.
2011-10-01
Surfaces can have a significant influence on the overall response of a continuum body but are often neglected or accounted for in an ad hoc manner. This work is concerned with a nonlinear continuum thermomechanics formulation which accounts for surface structures and includes the effects of diffusion and viscoelasticity. The formulation is presented within a thermodynamically consistent framework and elucidates the nature of the coupling between the various fields, and the surface and the bulk. Conservation principles are used to determine the form of the constitutive relations and the evolution equations. Restrictions on the jump in the temperature and the chemical potential between the surface and the bulk are not a priori assumptions, rather they arise from the reduced dissipation inequality on the surface and are shown to be satisfiable without imposing the standard assumptions of thermal and chemical slavery. The nature of the constitutive relations is made clear via an example wherein the form of the Helmholtz energy is explicitly given.
Moderately nonlinear diffuse-charge dynamics under an ac voltage.
Stout, Robert F; Khair, Aditya S
2015-09-01
The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of V_{o}/(k_{B}T/e), where V_{o} is the amplitude of the driving voltage and k_{B}T/e is the thermal voltage with k_{B} as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D/λ_{D}L, where D is the ion diffusivity, λ_{D} is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O(V_{o}^{3}) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in V_{o}. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing V_{o}. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer. PMID:26465471
NASA Astrophysics Data System (ADS)
Frank, T. D.
2008-02-01
We discuss two central claims made in the study by Bassler et al. [K.E. Bassler, G.H. Gunaratne, J.L. McCauley, Physica A 369 (2006) 343]. Bassler et al. claimed that Green functions and Langevin equations cannot be defined for nonlinear diffusion equations. In addition, they claimed that nonlinear diffusion equations are linear partial differential equations disguised as nonlinear ones. We review bottom-up and top-down approaches that have been used in the literature to derive Green functions for nonlinear diffusion equations and, in doing so, show that the first claim needs to be revised. We show that the second claim as well needs to be revised. To this end, we point out similarities and differences between non-autonomous linear Fokker-Planck equations and autonomous nonlinear Fokker-Planck equations. In this context, we raise the question whether Bassler et al.’s approach to financial markets is physically plausible because it necessitates the introduction of external traders and causes. Such external entities can easily be eliminated when taking self-organization principles and concepts of nonextensive thermostatistics into account and modeling financial processes by means of nonlinear Fokker-Planck equations.
Multigrid approaches to non-linear diffusion problems on unstructured meshes
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.; Bushnell, Dennis M. (Technical Monitor)
2001-01-01
The efficiency of three multigrid methods for solving highly non-linear diffusion problems on two-dimensional unstructured meshes is examined. The three multigrid methods differ mainly in the manner in which the nonlinearities of the governing equations are handled. These comprise a non-linear full approximation storage (FAS) multigrid method which is used to solve the non-linear equations directly, a linear multigrid method which is used to solve the linear system arising from a Newton linearization of the non-linear system, and a hybrid scheme which is based on a non-linear FAS multigrid scheme, but employs a linear solver on each level as a smoother. Results indicate that all methods are equally effective at converging the non-linear residual in a given number of grid sweeps, but that the linear solver is more efficient in cpu time due to the lower cost of linear versus non-linear grid sweeps.
Nonlinear oscillations of semigeostrophic Eady waves in the presence of diffusivity
NASA Astrophysics Data System (ADS)
Xu, Qin; Gu, Wei; Shouting, Gao
2005-01-01
Analyses are performed to examine the physical processes involved in nonlinear oscillations of Eady baroclinic waves obtained from viscous semigeostrophic models with two types of boundary conditions (freeslip and non-slip). By comparing with previous studies for the case of the free-slip boundary condition, it is shown that the nonlinear oscillations are produced mainly by the interaction between the baroclinic wave and zonal-mean state (total zonal-mean flow velocity and buoyancy stratification) but the timescale of the nonlinear oscillations is largely controlled by the diffusivity. When the boundary condition is non-slip, the nonlinear oscillations are further damped and slowed by the diffusive process. Since the free-slip (non-slip) boundary condition is the zero drag (infinite drag) limit of the more realistic drag boundary condition, the nonlinear oscillations obtained with the two types of boundary conditions are two extremes for more realistic nonlinear oscillations.
Nonlinear Theory of Anomalous Diffusion and Application to Fluorescence Correlation Spectroscopy
NASA Astrophysics Data System (ADS)
Boon, Jean Pierre; Lutsko, James F.
2015-12-01
The nonlinear theory of anomalous diffusion is based on particle interactions giving an explicit microscopic description of diffusive processes leading to sub-, normal, or super-diffusion as a result of competitive effects between attractive and repulsive interactions. We present the explicit analytical solution to the nonlinear diffusion equation which we then use to compute the correlation function which is experimentally measured by correlation spectroscopy. The theoretical results are applicable in particular to the analysis of fluorescence correlation spectroscopy of marked molecules in biological systems. More specifically we consider the cases of fluorescently labeled lipids in the plasma membrane and of fluorescent apoferritin (a spherically shaped oligomer) in a crowded dextran solution and we find that the nonlinear correlation spectra reproduce very well the experimental data indicating sub-diffusive molecular motion.
Unifying diffusion and seepage for nonlinear gas transport in multiscale porous media
NASA Astrophysics Data System (ADS)
Song, Hongqing; Wang, Yuhe; Wang, Jiulong; Li, Zhengyi
2016-09-01
We unify the diffusion and seepage process for nonlinear gas transport in multiscale porous media via a proposed new general transport equation. A coherent theoretical derivation indicates the wall-molecule and molecule-molecule collisions drive the Knudsen and collective diffusive fluxes, and constitute the system pressure across the porous media. A new terminology, nominal diffusion coefficient can summarize Knudsen and collective diffusion coefficients. Physical and numerical experiments show the support of the new formulation and provide approaches to obtain the diffusion coefficient and permeability simultaneously. This work has important implication for natural gas extraction and greenhouse gases sequestration in geological formations.
Nonlinear diffusion and viral spread through the leaf of a plant
NASA Astrophysics Data System (ADS)
Edwards, Maureen P.; Waterhouse, Peter M.; Munoz-Lopez, María Jesús; Anderssen, Robert S.
2016-10-01
The spread of a virus through the leaf of a plant is both spatially and temporally causal in that the present status depends on the past and the spatial spread is compactly supported and progresses outwards. Such spatial spread is known to occur for certain nonlinear diffusion processes. The first compactly supported solution for nonlinear diffusion equations appears to be that of Pattle published in 1959. In that paper, no explanation is given as to how the solution was derived. Here, we show how the solution can be derived using Lie symmetry analysis. This lays a foundation for exploring the behavior of other choices for nonlinear diffusion and exploring the addition of reaction terms which do not eliminate the compactly supported structure. The implications associated with using the reaction-diffusion equation to model the spatial-temporal spread of a virus through the leaf of a plant are discussed.
Analytical solutions for a nonlinear diffusion equation with convection and reaction
NASA Astrophysics Data System (ADS)
Valenzuela, C.; del Pino, L. A.; Curilef, S.
2014-12-01
Nonlinear diffusion equations with the convection and reaction terms are solved by using a power-law ansatz. This kind of equations typically appears in nonlinear problems of heat and mass transfer and flows in porous media. The solutions that we introduce in this work are analytical. At least, in the convection case, the result recovers its linear form as a special limit. In the reaction case, we define a class of nonlinearity to discuss the evolution of general solutions, we also add the Verhulst-like dynamics and global regulation. We think this method, based on this kind of ansatz, can also be applied to solve other nonlinear partial differential equations.
Submodels of model of nonlinear diffusion in the inhomogeneous medium involving absorption
Chirkunov, Yu. A.
2015-10-15
We study the five-parameter model, describing the process of nonlinear diffusion in an inhomogeneous medium in the presence of absorption, for which the differential equation of the model admits a continuous Lie group of transformations, acting on the set of its solutions. We found six submodels of the original model of nonlinear diffusion, with different symmetry properties. Of these six submodels, the five submodels with transient absorption, for which the absorption coefficient depends on time according to a power law, represent the greatest interest with a mathematical point of view and with the point of view of physical applications. For each of these nonlinear submodels, we obtained formulas for producing new solutions that contain arbitrary constants, and we found all invariant submodels. All essentially distinct invariant solutions describing these invariant submodels are found in an explicit form or are reduced to finding the solution of nonlinear integral equations. The presence of the arbitrary constants in the integral equations that determine these solutions provide new opportunities for analytical and numerical study of boundary value problems for the received submodels and, thus, for the original model of nonlinear diffusion. For the received invariant submodels, we studied diffusion processes for which at the initial moment of the time at a fixed point is specified as a concentration and its gradient or as a concentration and its velocity. Solving of boundary value problems describing these processes is reduced to the solving of nonlinear integral equations. We established the existence and uniqueness of solutions of these boundary value problems under some additional conditions. The obtained results can be used to study the diffusion of substances, diffusion of conduction electrons and other particles, diffusion of physical fields and propagation of heat in inhomogeneous medium, and also to study a turbulence (Leith model, differential
Willert, Jeffrey; Park, H.; Taitano, William
2015-11-01
High-order/low-order (or moment-based acceleration) algorithms have been used to significantly accelerate the solution to the neutron transport k-eigenvalue problem over the past several years. Recently, the nonlinear diffusion acceleration algorithm has been extended to solve fixed-source problems with anisotropic scattering sources. In this paper, we demonstrate that we can extend this algorithm to k-eigenvalue problems in which the scattering source is anisotropic and a significant acceleration can be achieved. Lastly, we demonstrate that the low-order, diffusion-like eigenvalue problem can be solved efficiently using a technique known as nonlinear elimination.
Willert, Jeffrey; Park, H.; Taitano, William
2015-10-12
High-order/low-order (or moment-based acceleration) algorithms have been used to significantly accelerate the solution to the neutron transport k-eigenvalue problem over the past several years. Recently, the nonlinear diffusion acceleration algorithm has been extended to solve fixed-source problems with anisotropic scattering sources. In this paper, we demonstrate that we can extend this algorithm to k-eigenvalue problems in which the scattering source is anisotropic and a significant acceleration can be achieved. Lastly, we demonstrate that the low-order, diffusion-like eigenvalue problem can be solved efficiently using a technique known as nonlinear elimination.
Nonlinearity Effects of Lateral Density Diffusion Coefficient on Gain-Guided VCSEL Performance
NASA Technical Reports Server (NTRS)
Li, Jian-Zhong; Cheung, Samson H.; Ning, C. Z.; Biegel, Bryan (Technical Monitor)
2001-01-01
Electron and hole diffusions in the plane of semiconductor quantum wells play an important part in the static and dynamic operations of semiconductor lasers. In this paper, we apply a hydrodynamic model developed from the semiconductor Bloch equations to numerically study the effects of nonlinearity in the diffusion coefficient on single mode operation and direct modulation of a gain-guided InGaAs/GaAs multiple quantum well laser, operating not too far from threshold. We found that a small diffusion coefficient is advantageous for lowering the threshold current and increasing the modulation bandwidth. Most importantly, the effects of nonlinearity in the coefficient can be approximately reproduced by replacing the coefficient with an effective constant diffusion coefficient, which corresponds roughly to the half height density of the density distribution.
Nonlinear structure of the diffusing gas-metal interface in a thermonuclear plasma.
Molvig, Kim; Vold, Erik L; Dodd, Evan S; Wilks, Scott C
2014-10-01
This Letter describes the theoretical structure of the plasma diffusion layer that develops from an initially sharp gas-metal interface. The layer dynamics under isothermal and isobaric conditions is considered so that only mass diffusion (mixing) processes can occur. The layer develops a distinctive structure with asymmetric and highly nonlinear features. On the gas side of the layer the diffusion coefficient goes nearly to zero, causing a sharp "front," or well defined boundary between mix layer and clean gas with similarities to the Marshak thermal waves. Similarity solutions for the nonlinear profiles are found and verified with full ion kinetic code simulations. A criterion for plasma diffusion to significantly affect burn is given.
NASA Astrophysics Data System (ADS)
Chiba, Ryoichi
2014-12-01
The two-dimensional differential transform method (DTM) is applied to solve the one-dimensional coupled heat and moisture diffusion problem for a slab with temperature-dependent thermal and moisture diffusivities, which are expressed by a linear function and an exponential function of temperature, respectively. One surface of the slab is subjected to convective hygrothermal loading and the other has constant prescribed temperature and moisture. Approximate analytical (series) solutions for the temperature and moisture profiles in the slab are derived. The transformed functions included in the solutions are obtained through a simple recursive procedure. Numerical results for a slab subjected to a sudden change in surface temperature illustrate the effects of temperature-dependent diffusivities on the transient temperature and moisture profiles of the slab. The results indicate that the nonlinear effect originating from the varying moisture diffusivity is not negligible for resin composites. The DTMis a useful new analytical method for solving nonlinear coupled transient problems.
Nonlinear diffusion in two-dimensional ordered porous media based on a free volume theory
NASA Astrophysics Data System (ADS)
Godec, A.; Gaberscek, M.; Jamnik, J.; Merzel, F.
2009-12-01
A continuum nonlinear diffusion model is developed to describe molecular transport in ordered porous media. An existing generic van der Waals equation of state based free volume theory of binary diffusion coefficients is modified and introduced into the two-dimensional diffusion equation. The resulting diffusion equation is solved numerically with the alternating-direction fully implicit method under Neumann boundary conditions. Two types of pore structure symmetries are considered, hexagonal and cubic. The former is modeled as parallel channels while in case of the latter equal-sized channels are placed perpendicularly thus creating an interconnected network. First, general features of transport in both systems are explored, followed by the analysis of the impact of molecular properties on diffusion inside and out of the porous matrix. The influence of pore size on the diffusion-controlled release kinetics is assessed and the findings used to comment recent experimental studies of drug release profiles from ordered mesoporous silicates.
Complex statistics and diffusion in nonlinear disordered particle chains.
Antonopoulos, Ch G; Bountis, T; Skokos, Ch; Drossos, L
2014-06-01
We investigate dynamically and statistically diffusive motion in a Klein-Gordon particle chain in the presence of disorder. In particular, we examine a low energy (subdiffusive) and a higher energy (self-trapping) case and verify that subdiffusive spreading is always observed. We then carry out a statistical analysis of the motion, in both cases, in the sense of the Central Limit Theorem and present evidence of different chaos behaviors, for various groups of particles. Integrating the equations of motion for times as long as 10(9), our probability distribution functions always tend to Gaussians and show that the dynamics does not relax onto a quasi-periodic Kolmogorov-Arnold-Moser torus and that diffusion continues to spread chaotically for arbitrarily long times.
Complex statistics and diffusion in nonlinear disordered particle chains
Antonopoulos, Ch. G.; Bountis, T.; Skokos, Ch.; Drossos, L.
2014-06-15
We investigate dynamically and statistically diffusive motion in a Klein-Gordon particle chain in the presence of disorder. In particular, we examine a low energy (subdiffusive) and a higher energy (self-trapping) case and verify that subdiffusive spreading is always observed. We then carry out a statistical analysis of the motion, in both cases, in the sense of the Central Limit Theorem and present evidence of different chaos behaviors, for various groups of particles. Integrating the equations of motion for times as long as 10{sup 9}, our probability distribution functions always tend to Gaussians and show that the dynamics does not relax onto a quasi-periodic Kolmogorov-Arnold-Moser torus and that diffusion continues to spread chaotically for arbitrarily long times.
Fitting degradation of shoreline scarps by a nonlinear diffusion model
Andrews, D.J.; Buckna, R.C.
1987-01-01
The diffusion model of degradation of topographic features is a promising means by which vertical offsets on Holocene faults might be dated. In order to calibrate the method, we have examined present-day profiles of wave-cut shoreline scarps of late Pleistocene lakes Bonneville and Lahontan. A table is included that allows easy application of the model to scarps with simple initial shape. -from Authors
Modeling magnetic field amplification in nonlinear diffusive shock acceleration
NASA Astrophysics Data System (ADS)
Vladimirov, Andrey
2009-02-01
This research was motivated by the recent observations indicating very strong magnetic fields at some supernova remnant shocks, which suggests in-situ generation of magnetic turbulence. The dissertation presents a numerical model of collisionless shocks with strong amplification of stochastic magnetic fields, self-consistently coupled to efficient shock acceleration of charged particles. Based on a Monte Carlo simulation of particle transport and acceleration in nonlinear shocks, the model describes magnetic field amplification using the state-of-the-art analytic models of instabilities in magnetized plasmas in the presence of non-thermal particle streaming. The results help one understand the complex nonlinear connections between the thermal plasma, the accelerated particles and the stochastic magnetic fields in strong collisionless shocks. Also, predictions regarding the efficiency of particle acceleration and magnetic field amplification, the impact of magnetic field amplification on the maximum energy of accelerated particles, and the compression and heating of the thermal plasma by the shocks are presented. Particle distribution functions and turbulence spectra derived with this model can be used to calculate the emission of observable nonthermal radiation.
Water Uptake, Diameter Change, and Nonlinear Diffusion in Tree Stems
Parlange, Jean-Yves; Turner, Neil C.; Waggoner, Paul E.
1975-01-01
A diffusion model for phloem swelling and contraction is proposed in which the rate of water movement changes markedly with moisture content. Good agreement between the actual swelling of the phloem of cotton stems and that predicted by the model was obtained. This result implies that water moves more readily into the phloem when it becomes wetter. This model also explains the lag of shrinkage of pine stems behind the water potential of the foliage and predicts that the lag is related to the thickness of the phloem. PMID:16659060
Arnold, J.; Kosson, D.S.; Garrabrants, A.; Meeussen, J.C.L.; Sloot, H.A. van der
2013-02-15
A robust numerical solution of the nonlinear Poisson-Boltzmann equation for asymmetric polyelectrolyte solutions in discrete pore geometries is presented. Comparisons to the linearized approximation of the Poisson-Boltzmann equation reveal that the assumptions leading to linearization may not be appropriate for the electrochemical regime in many cementitious materials. Implications of the electric double layer on both partitioning of species and on diffusive release are discussed. The influence of the electric double layer on anion diffusion relative to cation diffusion is examined.
Influence of time delay and nonlinear diffusion on herbivore outbreak
NASA Astrophysics Data System (ADS)
Sun, Gui-Quan; Chakraborty, Amit; Liu, Quan-Xing; Jin, Zhen; Anderson, Kurt E.; Li, Bai-Lian
2014-05-01
Herbivore outbreaks, a major form of natural disturbance in many ecosystems, often have devastating impacts on their food plants. Understanding those factors permitting herbivore outbreaks to occur is a long-standing issue in conventional studies of plant-herbivore interactions. These studies are largely concerned with the relative importance of intrinsic biological factors and extrinsic environmental variations in determining the degree of herbivore outbreaks. In this paper, we illustrated that how the time delay associated with plant defense responses to herbivore attacks and the spatial diffusion of herbivore jointly promote outbreaks of herbivore population. Using a reaction-diffusion model, we showed that there exists a threshold of time delay in plant-herbivore interactions; when time delay is below the threshold value, there is no herbivore outbreak. However, when time delay is above the threshold value, periodic outbreak of herbivore emerges. Furthermore, the results confirm that during the outbreak period, plants display much lower density than its normal level but higher in the inter-outbreak periods. Our results are supported by empirical findings.
Nonlinear stability in reaction-diffusion systems via optimal Lyapunov functions
NASA Astrophysics Data System (ADS)
Lombardo, S.; Mulone, G.; Trovato, M.
2008-06-01
We define optimal Lyapunov functions to study nonlinear stability of constant solutions to reaction-diffusion systems. A computable and finite radius of attraction for the initial data is obtained. Applications are given to the well-known Brusselator model and a three-species model for the spatial spread of rabies among foxes.
Symmetry analysis and group-invariant solutions to inhomogeneous nonlinear diffusion equation
NASA Astrophysics Data System (ADS)
Feng, Wei; Ji, Lina
2015-11-01
A classification of point symmetries for inhomogeneous nonlinear diffusion equation is discussed. The optimal systems of one-dimensional subalgebra for the equation are constructed. Explicit group-invariant solutions are derived by corresponding symmetry reductions. These solutions include static solutions, separable solutions and functionally separable solutions. The behaviors of blow-up, extinction and asymptotical behavior for these solutions are also described.
Pointwise nonlinear stability of nonlocalized modulated periodic reaction-diffusion waves
NASA Astrophysics Data System (ADS)
Jung, Soyeun; Zumbrun, Kevin
2016-10-01
In this paper, extending previous results of [2], we obtain pointwise nonlinear stability of periodic traveling reaction-diffusion waves, assuming spectral linearized stability, under nonlocalized perturbations. More precisely, we establish pointwise estimate of nonlocalized modulational perturbation under a small initial perturbation consisting of a nonlocalized modulation plus a localized perturbation decaying algebraically.
Some applications of nonlinear diffusion to processing of dynamic evolution images
Goltsov, Alexey N.; Nikishov, Sergey A.
1997-05-15
Model nonlinear diffusion equation with the most simple Landau-Ginzburg free energy functional was applied to locate boundaries between meaningful regions of low-level images. The method is oriented to processing images of objects that are a result of dynamic evolution: images of different organs and tissues obtained by radiography and NMR methods, electron microscope images of morphogenesis fields, etc. In the methods developed by us, parameters of the nonlinear diffusion model are chosen on the basis of the preliminary treatment of the images. The parameters of the Landau-Ginzburg free energy functional are extracted from the structure factor of the images. Owing to such a choice of the model parameters, the image to be processed is located in the vicinity of the steady-state of the diffusion equation. The suggested method allows one to separate distinct structures having specific space characteristics from the whole image. The method was applied to processing X-ray images of the lung.
Nonlinear diffusion-wave equation for a gas in a regenerator subject to temperature gradient
NASA Astrophysics Data System (ADS)
Sugimoto, N.
2015-10-01
This paper derives an approximate equation for propagation of nonlinear thermoacoustic waves in a gas-filled, circular pore subject to temperature gradient. The pore radius is assumed to be much smaller than a thickness of thermoviscous diffusion layer, and the narrow-tube approximation is used in the sense that a typical axial length associated with temperature gradient is much longer than the radius. Introducing three small parameters, one being the ratio of the pore radius to the thickness of thermoviscous diffusion layer, another the ratio of a typical speed of thermoacoustic waves to an adiabatic sound speed and the other the ratio of a typical magnitude of pressure disturbance to a uniform pressure in a quiescent state, a system of fluid dynamical equations for an ideal gas is reduced asymptotically to a nonlinear diffusion-wave equation by using boundary conditions on a pore wall. Discussion on a temporal mean of an excess pressure due to periodic oscillations is included.
Doubly Distributed Transactions
2014-08-25
Doubly Distributed Transactions (D2T) offers a technique for managing operations from a set of parallel clients with a collection of distributed services. It detects and manages faults. Example code with a test harness is also provided
Skeist, S. Merrill; Baker, Richard H.
2005-10-11
An electro-mechanical energy conversion system coupled between an energy source and an energy load including an energy converter device having a doubly fed induction machine coupled between the energy source and the energy load to convert the energy from the energy source and to transfer the converted energy to the energy load and an energy transfer multiplexer coupled to the energy converter device to control the flow of power or energy through the doubly fed induction machine.
Nonlinear preferential rewiring in fixed-size networks as a diffusion process.
Johnson, Samuel; Torres, Joaquín J; Marro, Joaquín
2009-05-01
We present an evolving network model in which the total numbers of nodes and edges are conserved, but in which edges are continuously rewired according to nonlinear preferential detachment and reattachment. Assuming power-law kernels with exponents alpha and beta , the stationary states which the degree distributions evolve toward exhibit a second-order phase transition-from relatively homogeneous to highly heterogeneous (with the emergence of starlike structures) at alpha=beta . Temporal evolution of the distribution in this critical regime is shown to follow a nonlinear diffusion equation, arriving at either pure or mixed power laws of exponents -alpha and 1-alpha .
Nonlinear Waves in Reaction Diffusion Systems: The Effect of Transport Memory
HURD,ALAN J.; KENKRE,V.M.; MANNE,K.K.
1999-11-04
Motivated by the problem of determining stress distributions in granular materials, we study the effect of finite transport correlation times on the propagation of nonlinear wavefronts in reaction diffusion systems. We obtain new results such as the possibility of spatial oscillations in the wavefront shape for certain values of the system parameters and high enough wavefront speeds. We also generalize earlier known results concerning the minimum wavefront speed and shape-speed relationships stemming from the finiteness of the correlation times. Analytic investigations are made possible by a piece-wise linear representation of the nonlinearity.
Malacarne, L C; Mendes, R S; Pedron, I T; Lenzi, E K
2001-03-01
The nonlinear diffusion equation partial delta rho/delta t=D Delta rho(nu) is analyzed here, where Delta[triple bond](1/r(d-1))(delta/delta r)r(d-1-theta) delta/delta r, and d, theta, and nu are real parameters. This equation unifies the anomalous diffusion equation on fractals (nu=1) and the spherical anomalous diffusion for porous media (theta=0). An exact point-source solution is obtained, enabling us to describe a large class of subdiffusion [ theta>(1-nu)d], "normal" diffusion [theta=(1-nu)d] and superdiffusion [theta<(1-nu)d]. Furthermore, a thermostatistical basis for this solution is given from the maximum entropic principle applied to the Tsallis entropy.
Typical and rare fluctuations in nonlinear driven diffusive systems with dissipation.
Hurtado, Pablo I; Lasanta, A; Prados, A
2013-08-01
We consider fluctuations of the dissipated energy in nonlinear driven diffusive systems subject to bulk dissipation and boundary driving. With this aim, we extend the recently introduced macroscopic fluctuation theory to nonlinear driven dissipative media, starting from the fluctuating hydrodynamic equations describing the system mesoscopic evolution. Interestingly, the action associated with a path in mesoscopic phase space, from which large-deviation functions for macroscopic observables can be derived, has the same simple form as in nondissipative systems. This is a consequence of the quasielasticity of microscopic dynamics, required in order to have a nontrivial competition between diffusion and dissipation at the mesoscale. Euler-Lagrange equations for the optimal density and current fields that sustain an arbitrary dissipation fluctuation are also derived. A perturbative solution thereof shows that the probability distribution of small fluctuations is always Gaussian, as expected from the central limit theorem. On the other hand, strong separation from the Gaussian behavior is observed for large fluctuations, with a distribution which shows no negative branch, thus violating the Gallavotti-Cohen fluctuation theorem, as expected from the irreversibility of the dynamics. The dissipation large-deviation function exhibits simple and general scaling forms for weakly and strongly dissipative systems, with large fluctuations favored in the former case but heavily suppressed in the latter. We apply our results to a general class of diffusive lattice models for which dissipation, nonlinear diffusion, and driving are the key ingredients. The theoretical predictions are compared to extensive numerical simulations of the microscopic models, and excellent agreement is found. Interestingly, the large-deviation function is in some cases nonconvex beyond some dissipation. These results show that a suitable generalization of macroscopic fluctuation theory is capable of
Diffusion dynamics near critical bifurcations in a nonlinearly damped pendulum system
NASA Astrophysics Data System (ADS)
Sakthivel, G.; Rajasekar, S.
2012-03-01
We numerically study the diffusion dynamics near critical bifurcations such as sudden widening of the size of a chaotic attractor, intermittency and band-merging of a chaotic attractor in a nonlinearly damped and periodically driven pendulum system. The system is found to show only normal diffusion. Near sudden widening and intermittency crisis power-law variation of diffusion constant with the control parameter ω of the external periodic force f sin ωt is found while linear variation of it is observed near band-merging crisis. The value of the exponent in the power-law relation varies with the damping coefficient and the strength of the added Gaussian white noise.
NASA Technical Reports Server (NTRS)
Karimbadi, H.; Krauss-Varban, D.
1992-01-01
A novel diffusion formalism that takes into account the finite width of resonances is presented. The resonance diagram technique is shown to reproduce the details of the particle orbits very accurately, and can be used to determine the acceleration/scattering in the presence of a given wave spectrum. Ways in which the nonlinear orbits can be incorporated into the diffusion equation are shown. The resulting diffusion equation is an extension of the Q-L theory to cases where the waves have large amplitudes and/or are coherent. This new equation does not have a gap at 90 deg in cases where the individual orbits can cross the gap. The conditions under which the resonance gap at 90-deg pitch angle exits are also examined.
NASA Astrophysics Data System (ADS)
Aziz, Taha; Fatima, Aeeman; Khalique, Chaudry Masood
An analytical approach based on the compatibility concept is employed to solve a nonlinear reaction-diffusion model arising in mathematical biology. The solution process makes it extremely easy to obtain a relatively accurate closed-form solution of the model. The pencil-and-paper solution procedure can be extended to other class of nonlinear problems of similar kind.
Stretch diffusion and heat conduction in one-dimensional nonlinear lattices.
Gao, Zhibin; Li, Nianbei; Li, Baowen
2016-03-01
For heat conduction in one-dimensional (1D) nonlinear Hamiltonian lattices, it has been known that conserved quantities play an important role in determining the actual heat conduction behavior. In closed or microcanonical Hamiltonian systems, the total energy and stretch are always conserved. Depending on the existence of external on-site potential, the total momentum can be conserved or not. All the momentum-conserving lattices have anomalous heat conduction except the 1D coupled rotator lattice. It was recently claimed that "whenever stretch (momentum) is not conserved in a 1D model, the momentum (stretch) and energy fields exhibit normal diffusion." The stretch in a coupled rotator lattice was also argued to be nonconserved due to the requirement of a finite partition function, which enables the coupled rotator lattice to fulfill this claim. In this work, we will systematically investigate stretch diffusion and heat conduction in terms of energy diffusion for typical 1D nonlinear lattices. Contrary to what was claimed, no clear connection between conserved quantities and heat conduction can be established. The actual situation might be more complicated than what was proposed. PMID:27078315
Critical behavior of a class of nonlinear stochastic models of diffusion of information
NASA Astrophysics Data System (ADS)
Sharma, C. L.; Pathria, R. K.; Karmeshu
1982-12-01
A theoretical analysis based on the concepts and techniques of statistical physics is carried out for two nonlinear models of diffusion of information-one in a closed population and the other in an open one. Owing to interpersonal contacts among the members of the population, the models exhibit a cooperative behavior when a certain parameter of the problem approaches a critical value. Mathematical similarities in the behavior of the two models, in the vicinity of the critical point, are so impelling that one is tempted to investigate the corresponding behavior of a generalized model, which can be done by carrying out a systematic system-size expansion of the master equation of the process and thereby deriving a nonlinear Fokker-Planck equation for the relevant probability distribution. This establishes a broader class of systems displaying identical behavior in the critical region and also elucidates the role played by fluctuations in bringing about the cooperative phenomenon.
Dynamics of a Diffusive Predator-Prey Model with General Nonlinear Functional Response
2014-01-01
We study a diffusive predator-prey model with nonconstant death rate and general nonlinear functional response. Firstly, stability analysis of the equilibrium for reduced ODE system is discussed. Secondly, sufficient and necessary conditions which guarantee the predator and the prey species to be permanent are obtained. Furthermore, sufficient conditions for the global asymptotical stability of the unique positive equilibrium of the system are derived by using the method of Lyapunov function. Finally, we show that there are no nontrivial steady state solutions for certain parameter configuration. PMID:24688422
Large time behavior in a nonlinear age-dependent population dynamics problem with spatial diffusion.
Langlais, M
1988-01-01
In this work we analyze the large time behavior in a nonlinear model of population dynamics with age-dependence and spatial diffusion. We show that when t----+ infinity either the solution of our problem goes to 0 or it stabilizes to a nontrivial stationary solution. We give two typical examples where the stationary solutions can be evaluated upon solving very simple partial differential equations. As a by-product of the extinction case we find a necessary condition for a nontrivial periodic solution to exist. Numerical computations not described below show a rapid stabilization.
Langrock, Carsten; Roussev, Rostislav V; Nava, Giovanni; Minzioni, Paolo; Argiolas, Nicola; Sada, Cinzia; Fejer, Martin M
2016-08-20
Photorefractive-damage- (PRD) resistant zirconium-oxide-doped lithium niobate is investigated as a substrate for the realization of annealed proton-exchanged (APE) waveguides. Its advantages are a favorable distribution coefficient, PRD resistance comparable to magnesium-oxide-doped lithium niobate, and a proton-diffusion behavior resembling congruent lithium niobate. A 1D model for APE waveguides was developed based on a previous model for congruently melting lithium niobate. Evidence for a nonlinear index dependence on concentration was found. PMID:27556972
Hu, Weiming; Hu, Ruiguang; Xie, Nianhua; Ling, Haibin; Maybank, Stephen
2014-04-01
In this paper, we propose saliency driven image multiscale nonlinear diffusion filtering. The resulting scale space in general preserves or even enhances semantically important structures such as edges, lines, or flow-like structures in the foreground, and inhibits and smoothes clutter in the background. The image is classified using multiscale information fusion based on the original image, the image at the final scale at which the diffusion process converges, and the image at a midscale. Our algorithm emphasizes the foreground features, which are important for image classification. The background image regions, whether considered as contexts of the foreground or noise to the foreground, can be globally handled by fusing information from different scales. Experimental tests of the effectiveness of the multiscale space for the image classification are conducted on the following publicly available datasets: 1) the PASCAL 2005 dataset; 2) the Oxford 102 flowers dataset; and 3) the Oxford 17 flowers dataset, with high classification rates. PMID:24569440
NASA Astrophysics Data System (ADS)
Hristov, Jordan
2016-03-01
Closed form approximate solutions to nonlinear heat (mass) diffusion equation with power-law nonlinearity of the thermal (mass) diffusivity have been developed by the integral-balance method avoiding the commonly used linearization by the Kirchhoff transformation. The main improvement of the solution is based on the double-integration technique and a new approach to the space derivative. Solutions to Dirichlet and Neumann boundary condition problems have been developed and benchmarked against exact numerical and approximate analytical solutions available in the literature.
Steingrimsson, Jon Arni; Diao, Liqun; Molinaro, Annette M; Strawderman, Robert L
2016-09-10
Estimating a patient's mortality risk is important in making treatment decisions. Survival trees are a useful tool and employ recursive partitioning to separate patients into different risk groups. Existing 'loss based' recursive partitioning procedures that would be used in the absence of censoring have previously been extended to the setting of right censored outcomes using inverse probability censoring weighted estimators of loss functions. In this paper, we propose new 'doubly robust' extensions of these loss estimators motivated by semiparametric efficiency theory for missing data that better utilize available data. Simulations and a data analysis demonstrate strong performance of the doubly robust survival trees compared with previously used methods. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27037609
NASA Astrophysics Data System (ADS)
Fernandes, Ryan I.; Fairweather, Graeme
2012-08-01
An alternating direction implicit (ADI) orthogonal spline collocation (OSC) method is described for the approximate solution of a class of nonlinear reaction-diffusion systems. Its efficacy is demonstrated on the solution of well-known examples of such systems, specifically the Brusselator, Gray-Scott, Gierer-Meinhardt and Schnakenberg models, and comparisons are made with other numerical techniques considered in the literature. The new ADI method is based on an extrapolated Crank-Nicolson OSC method and is algebraically linear. It is efficient, requiring at each time level only O(N) operations where N is the number of unknowns. Moreover, it is shown to produce approximations which are of optimal global accuracy in various norms, and to possess superconvergence properties.
The nonlinear diffusion limit for generalized Carleman models: the initial-boundary value problem
NASA Astrophysics Data System (ADS)
Golse, François; Salvarani, Francesco
2007-04-01
Consider the initial-boundary value problem for the 2-speed Carleman model of the Boltzmann equation of the kinetic theory of gases, (see Carleman 1957 Problèmes Mathématiques Dans la Théorie Cinétique des Gaz (Uppsala: Almqvist-Wiksells)), set in some bounded interval with boundary conditions prescribing the density of particles entering the interval. Under the usual parabolic scaling, a nonlinear diffusion limit is established for this problem. In fact, the techniques presented here allow treatment generalizations of the Carleman system where the collision frequency is proportional to the αth power of the macroscopic density, with α ∈ [-1, 1].
Li, Yin-Huan; Shelor, C Phillip; Dasgupta, Purnendu K
2015-01-20
We present an absorption spectrometric method using a polytetrafluoroethylene (PTFE) cell as a diffuse reflector. The system was used for monitoring ultrapure water. All compounds absorb to some degree at low UV wavelengths, and the absorption at 214 nm from a zinc lamp source was monitored using a charge-coupled device (CCD) spectrometer. The absorption was interpreted in terms of total organic carbon present. The cell acts as a nonlinear absorbance amplifier, improving both the limit of detection (LOD) and the dynamic range. Potassium hydrogen phthalate (KHP) and glucose were used to evaluate the system and provided respective LODs of 46.5 ng/L and 4.5 mg/L as carbon. Although the physical path length was 25 cm, a maximum effective path length of 280 cm was observed at the lowest tested KHP concentrations. The system is intended for real-time monitoring of ultrapure water.
Median-prior tomography reconstruction combined with nonlinear anisotropic diffusion filtering
NASA Astrophysics Data System (ADS)
Yan, Jianhua; Yu, Jun
2007-04-01
Positron emission tomography (PET) is becoming increasingly important in the fields of medicine and biology. Penalized iterative algorithms based on maximum a posteriori (MAP) estimation for image reconstruction in emission tomography place conditions on which types of images are accepted as solutions. The recently introduced median root prior (MRP) favors locally monotonic images. MRP can preserve sharp edges, but a steplike streaking effect and much noise are still observed in the reconstructed image, both of which are undesirable. An MRP tomography reconstruction combined with nonlinear anisotropic diffusion interfiltering is proposed for removing noise and preserving edges. Analysis shows that the proposed algorithm is capable of producing better reconstructed images compared with those reconstructed by conventional maximum-likelihood expectation maximization (MLEM), MAP, and MRP-based algorithms in PET image reconstruction.
Basko, D.M.
2011-07-15
Research Highlights: > In a one-dimensional disordered chain of oscillators all normal modes are localized. > Nonlinearity leads to chaotic dynamics. > Chaos is concentrated on rare chaotic spots. > Chaotic spots drive energy exchange between oscillators. > Macroscopic transport coefficients are obtained. - Abstract: The subject of this study is the long-time equilibration dynamics of a strongly disordered one-dimensional chain of coupled weakly anharmonic classical oscillators. It is shown that chaos in this system has a very particular spatial structure: it can be viewed as a dilute gas of chaotic spots. Each chaotic spot corresponds to a stochastic pump which drives the Arnold diffusion of the oscillators surrounding it, thus leading to their relaxation and thermalization. The most important mechanism of equilibration at long distances is provided by random migration of the chaotic spots along the chain, which bears analogy with variable-range hopping of electrons in strongly disordered solids. The corresponding macroscopic transport equations are obtained.
NASA Astrophysics Data System (ADS)
Passalacqua, Paola; Do Trung, Tien; Foufoula-Georgiou, Efi; Sapiro, Guillermo; Dietrich, William E.
2010-03-01
A geometric framework for the automatic extraction of channels and channel networks from high-resolution digital elevation data is introduced in this paper. The proposed approach incorporates nonlinear diffusion for the preprocessing of the data, both to remove noise and to enhance features that are critical to the network extraction. Following this preprocessing, channels are defined as curves of minimal effort, or geodesics, where the effort is measured on the basis of fundamental geomorphological characteristics such as flow accumulation area and isoheight contours curvature. The merits of the proposed methodology, and especially the computational efficiency and accurate localization of the extracted channels, are demonstrated using light detection and ranging (lidar) data of the Skunk Creek, a tributary of the South Fork Eel River basin in northern California.
Convection and reaction in a diffusive boundary layer in a porous medium: Nonlinear dynamics
NASA Astrophysics Data System (ADS)
Andres, Jeanne Therese H.; Cardoso, Silvana S. S.
2012-09-01
We study numerically the nonlinear interactions between chemical reaction and convective fingering in a diffusive boundary layer in a porous medium. The reaction enhances stability by consuming a solute that is unstably distributed in a gravitational field. We show that chemical reaction profoundly changes the dynamics of the system, by introducing a steady state, shortening the evolution time, and altering the spatial patterns of velocity and concentration of solute. In the presence of weak reaction, finger growth and merger occur effectively, driving strong convective currents in a thick layer of solute. However, as the reaction becomes stronger, finger growth is inhibited, tip-splitting is enhanced and the layer of solute becomes much thinner. Convection enhances the mass flux of solute consumed by reaction in the boundary layer but has a diminishing effect as reaction strength increases. This nonlinear behavior has striking differences to the density fingering of traveling reaction fronts, for which stronger chemical kinetics result in more effective finger merger owing to an increase in the speed of the front. In a boundary layer, a strong stabilizing effect of reaction can maintain a long-term state of convection in isolated fingers of wavelength comparable to that at onset of instability.
Lattice Boltzmann methods for some 2-D nonlinear diffusion equations:Computational results
Elton, B.H.; Rodrigue, G.H. . Dept. of Applied Science Lawrence Livermore National Lab., CA ); Levermore, C.D. . Dept. of Mathematics)
1990-01-01
In this paper we examine two lattice Boltzmann methods (that are a derivative of lattice gas methods) for computing solutions to two two-dimensional nonlinear diffusion equations of the form {partial derivative}/{partial derivative}t u = v ({partial derivative}/{partial derivative}x D(u){partial derivative}/{partial derivative}x u + {partial derivative}/{partial derivative}y D(u){partial derivative}/{partial derivative}y u), where u = u({rvec x},t), {rvec x} {element of} R{sup 2}, v is a constant, and D(u) is a nonlinear term that arises from a Chapman-Enskog asymptotic expansion. In particular, we provide computational evidence supporting recent results showing that the methods are second order convergent (in the L{sub 1}-norm), conservative, conditionally monotone finite difference methods. Solutions computed via the lattice Boltzmann methods are compared with those computed by other explicit, second order, conservative, monotone finite difference methods. Results are reported for both the L{sub 1}- and L{sub {infinity}}-norms.
Lee, Shiu-Hang; Nagataki, Shigehiro; Ellison, Donald C. E-mail: nagataki@yukawa.kyoto-u.ac.jp
2012-05-10
To better model the efficient production of cosmic rays (CRs) in supernova remnants (SNRs) with the associated coupling between CR production and SNR dynamics, we have generalized an existing cr-hydro-NEI code to include the following processes: (1) an explicit calculation of the upstream precursor structure including the position-dependent flow speed, density, temperature, and magnetic field strength; (2) a momentum- and space-dependent CR diffusion coefficient; (3) an explicit calculation of magnetic field amplification; (4) calculation of the maximum CR momentum using the amplified magnetic field; (5) a finite Alfven speed for the particle scattering centers; and (6) the ability to accelerate a superthermal seed population of CRs, as well as the ambient thermal plasma. While a great deal of work has been done modeling SNRs, most work has concentrated on either the continuum emission from relativistic electrons or ions or the thermal emission from the shock heated plasma. Our generalized code combines these elements and describes the interplay between CR production and SNR evolution, including the nonlinear coupling of efficient diffusive shock acceleration, based mainly on the work of P. Blasi and coworkers, and a non-equilibrium ionization (NEI) calculation of thermal X-ray line emission. We believe that our generalized model will provide a consistent modeling platform for SNRs, including those interacting with molecular clouds, and improve the interpretation of current and future observations, including the high-quality spectra expected from Astro-H. SNR RX J1713.7-3946 is modeled as an example.
Budroni, M A
2015-12-01
Cross diffusion, whereby a flux of a given species entrains the diffusive transport of another species, can trigger buoyancy-driven hydrodynamic instabilities at the interface of initially stable stratifications. Starting from a simple three-component case, we introduce a theoretical framework to classify cross-diffusion-induced hydrodynamic phenomena in two-layer stratifications under the action of the gravitational field. A cross-diffusion-convection (CDC) model is derived by coupling the fickian diffusion formalism to Stokes equations. In order to isolate the effect of cross-diffusion in the convective destabilization of a double-layer system, we impose a starting concentration jump of one species in the bottom layer while the other one is homogeneously distributed over the spatial domain. This initial configuration avoids the concurrence of classic Rayleigh-Taylor or differential-diffusion convective instabilities, and it also allows us to activate selectively the cross-diffusion feedback by which the heterogeneously distributed species influences the diffusive transport of the other species. We identify two types of hydrodynamic modes [the negative cross-diffusion-driven convection (NCC) and the positive cross-diffusion-driven convection (PCC)], corresponding to the sign of this operational cross-diffusion term. By studying the space-time density profiles along the gravitational axis we obtain analytical conditions for the onset of convection in terms of two important parameters only: the operational cross-diffusivity and the buoyancy ratio, giving the relative contribution of the two species to the global density. The general classification of the NCC and PCC scenarios in such parameter space is supported by numerical simulations of the fully nonlinear CDC problem. The resulting convective patterns compare favorably with recent experimental results found in microemulsion systems. PMID:26764804
NASA Astrophysics Data System (ADS)
Budroni, M. A.
2015-12-01
Cross diffusion, whereby a flux of a given species entrains the diffusive transport of another species, can trigger buoyancy-driven hydrodynamic instabilities at the interface of initially stable stratifications. Starting from a simple three-component case, we introduce a theoretical framework to classify cross-diffusion-induced hydrodynamic phenomena in two-layer stratifications under the action of the gravitational field. A cross-diffusion-convection (CDC) model is derived by coupling the fickian diffusion formalism to Stokes equations. In order to isolate the effect of cross-diffusion in the convective destabilization of a double-layer system, we impose a starting concentration jump of one species in the bottom layer while the other one is homogeneously distributed over the spatial domain. This initial configuration avoids the concurrence of classic Rayleigh-Taylor or differential-diffusion convective instabilities, and it also allows us to activate selectively the cross-diffusion feedback by which the heterogeneously distributed species influences the diffusive transport of the other species. We identify two types of hydrodynamic modes [the negative cross-diffusion-driven convection (NCC) and the positive cross-diffusion-driven convection (PCC)], corresponding to the sign of this operational cross-diffusion term. By studying the space-time density profiles along the gravitational axis we obtain analytical conditions for the onset of convection in terms of two important parameters only: the operational cross-diffusivity and the buoyancy ratio, giving the relative contribution of the two species to the global density. The general classification of the NCC and PCC scenarios in such parameter space is supported by numerical simulations of the fully nonlinear CDC problem. The resulting convective patterns compare favorably with recent experimental results found in microemulsion systems.
Sun, Dajun D; Lee, Ping I
2015-04-01
The importance of rate of supersaturation generation on the kinetic solubility profiles of amorphous systems has recently been shown by us; however, the previous focus was limited to constant rates of supersaturation generation. The objective of the current study is to further examine the effect of nonlinear rate profiles of supersaturation generation in amorphous systems, including (1) instantaneous or infinite rate (i.e., initial degree of supersaturation), (2) first-order rate (e.g., from dissolution of amorphous drug particles), and (3) matrix diffusion regulated rate (e.g., drug release from amorphous solid dispersions (ASDs) based on cross-linked poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels), on the kinetic solubility profiles of a model poorly soluble drug indomethacin (IND) under nonsink dissolution conditions. The previously established mechanistic model taking into consideration both the crystal growth and ripening processes was extended to predict the evolution of supersaturation resulting from nonlinear rates of supersaturation generation. Our results confirm that excessively high initial supersaturation or a rapid supersaturation generation leads to a surge in maximum supersaturation followed by a rapid decrease in drug concentration owing to supersaturation-induced precipitation; however, an exceedingly low degree of supersaturation or a slow rate of supersaturation generation does not sufficiently raise the supersaturation level, which results in a lower but broader maximum kinetic solubility profile. Our experimental data suggest that an optimal area-under-the-curve of the kinetic solubility profiles exists at an intermediate initial supersaturation level for the amorphous systems studied here, which agrees well with the predicted trend. Our model predictions also support our experimental findings that IND ASD in cross-linked PHEMA exhibits a unique kinetic solubility profile because the resulting supersaturation level is governed by a matrix
Lee, Shiu-Hang; Kamae, Tuneyoshi; Ellison, Donald C.
2008-07-02
We present a 3-dimensional model of supernova remnants (SNRs) where the hydrodynamical evolution of the remnant is modeled consistently with nonlinear diffusive shock acceleration occurring at the outer blast wave. The model includes particle escape and diffusion outside of the forward shock, and particle interactions with arbitrary distributions of external ambient material, such as molecular clouds. We include synchrotron emission and cooling, bremsstrahlung radiation, neutral pion production, inverse-Compton (IC), and Coulomb energy-loss. Boardband spectra have been calculated for typical parameters including dense regions of gas external to a 1000 year old SNR. In this paper, we describe the details of our model but do not attempt a detailed fit to any specific remnant. We also do not include magnetic field amplification (MFA), even though this effect may be important in some young remnants. In this first presentation of the model we don't attempt a detailed fit to any specific remnant. Our aim is to develop a flexible platform, which can be generalized to include effects such as MFA, and which can be easily adapted to various SNR environments, including Type Ia SNRs, which explode in a constant density medium, and Type II SNRs, which explode in a pre-supernova wind. When applied to a specific SNR, our model will predict cosmic-ray spectra and multi-wavelength morphology in projected images for instruments with varying spatial and spectral resolutions. We show examples of these spectra and images and emphasize the importance of measurements in the hard X-ray, GeV, and TeV gamma-ray bands for investigating key ingredients in the acceleration mechanism, and for deducing whether or not TeV emission is produced by IC from electrons or pion-decay from protons.
Fomichev, S. V.; Becker, W.
2010-06-15
Both linear and nonlinear scattering and absorption of a laser pulse by spherical nanoclusters with free electrons and with a diffuse surface are considered in the collisionless hydrodynamics approximation. The developed model of forced collective motion of electrons confined to a cluster permits one consistently to introduce into the theory all the sources of nonlinearity, as well as the inhomogeneity of the cluster near its boundary. Two different perturbation theories corresponding to different laser intensity ranges are developed in this context, and both cold metal clusters and hot laser-heated or -ionized clusters are considered within the same approach. In the present article, after developing the full nonlinear model, the linear response to the laser field of the free-electron cluster with diffuse surface is investigated in detail, especially the properties of the linear Mie resonance (width and position). Under certain conditions, depending on the various cluster parameters secondary resonances are found. The properties of resonance-enhanced third-order harmonic generation and nonlinear laser absorption and their dependence on the shape of the diffuse surface will be presented separately.
Weeratunga, S K; Kamath, C
2001-12-20
Removing noise from data is often the first step in data analysis. Denoising techniques should not only reduce the noise, but do so without blurring or changing the location of the edges. Many approaches have been proposed to accomplish this; in this paper, they focus on one such approach, namely the use of non-linear diffusion operators. This approach has been studied extensively from a theoretical viewpoint ever since the 1987 work of Perona and Malik showed that non-linear filters outperformed the more traditional linear Canny edge detector. They complement this theoretical work by investigating the performance of several isotropic diffusion operators on test images from scientific domains. They explore the effects of various parameters such as the choice of diffusivity function, explicit and implicit methods for the discretization of the PDE, and approaches for the spatial discretization of the non-linear operator etc. They also compare these schemes with simple spatial filters and the more complex wavelet-based shrinkage techniques. The empirical results show that, with an appropriate choice of parameters, diffusion-based schemes can be as effective as competitive techniques.
Unexpected doubly-magic nucleus.
Janssens, R. V. F.; Physics
2009-01-01
Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.
Rényi entropy and improved equilibration rates to self-similarity for nonlinear diffusion equations
NASA Astrophysics Data System (ADS)
Carrillo, J. A.; Toscani, G.
2014-12-01
We investigate the large-time asymptotics of nonlinear diffusion equations ut = Δup in dimension n ⩾ 1, in the exponent interval p > n/(n + 2), when the initial datum u0 is of bounded second moment. Precise rates of convergence to the Barenblatt profile in terms of the relative Rényi entropy are demonstrated for finite-mass solutions defined in the whole space when they are re-normalized at each time t > 0 with respect to their own second moment, as proposed by Carrillo et al (2006 Arch. Ration. Mech. Anal. 180 127-49) and Toscani (2005 J. Evol. Eqns 5 185-203). The analysis shows that, in the range p > max((n - 1)/n, n/(n + 2)), the relative Rényi entropy exhibits a better decay, for intermediate times, with respect to the standard Ralston-Newman entropy. The result follows by a suitable use of sharp Gagliardo-Nirenberg-Sobolev inequalities considered by Dolbeault and Toscani (2013 Ann. Inst. Henri Poincare (C) Non Linear Anal. 30 917-34), and their information-theoretical proof (Savaré and Toscani 2014 IEEE Trans. Inform. Theory 60 2687-93), known as concavity of Rényi entropy power.
Scaling and synchronization in a ring of diffusively coupled nonlinear oscillators.
Senthilkumar, D V; Muruganandam, P; Lakshmanan, M; Kurths, J
2010-06-01
Chaos synchronization in a ring of diffusively coupled nonlinear oscillators driven by an external identical oscillator is studied. Based on numerical simulations we show that by introducing additional couplings at (mN(c)+1)-th oscillators in the ring, where m is an integer and N(c) is the maximum number of synchronized oscillators in the ring with a single coupling, the maximum number of oscillators that can be synchronized can be increased considerably beyond the limit restricted by size instability. We also demonstrate that there exists an exponential relation between the number of oscillators that can support stable synchronization in the ring with the external drive and the critical coupling strength ε(c) with a scaling exponent γ. The critical coupling strength is calculated by numerically estimating the synchronization error and is also confirmed from the conditional Lyapunov exponents of the coupled systems. We find that the same scaling relation exists for m couplings between the drive and the ring. Further, we have examined the robustness of the synchronous states against Gaussian white noise and found that the synchronization error exhibits a power-law decay as a function of the noise intensity indicating the existence of both noise-enhanced and noise-induced synchronizations depending on the value of the coupling strength ε. In addition, we have found that ε(c) shows an exponential decay as a function of the number of additional couplings. These results are demonstrated using the paradigmatic models of Rössler and Lorenz oscillators.
Mekhiche, M.; Pera, T.; Marechal, Y.
1995-05-01
The anisotropic and nonlinear behavior of doubly oriented and non-oriented sheets are modeled using the coenergy density. These models have been implemented in a finite element computation. A large generator has been modeled and the advantages of doubly oriented sheets compared to the conventional non-oriented ones are shown.
NASA Astrophysics Data System (ADS)
Kengne, Emmanuel; Saydé, Michel; Ben Hamouda, Fathi; Lakhssassi, Ahmed
2013-11-01
Analytical entire traveling wave solutions to the 1+1 density-dependent nonlinear reaction-diffusion equation via the extended generalized Riccati equation mapping method are presented in this paper. This equation can be regarded as an extension case of the Fisher-Kolmogoroff equation, which is used for studying insect and animal dispersal with growth dynamics. The analytical solutions are then used to investigate the effect of equation parameters on the population distribution.
Radio emission and nonlinear diffusive shock acceleration of cosmic rays in the supernova SN 1993J
NASA Astrophysics Data System (ADS)
Tatischeff, V.
2009-05-01
Aims: The extensive observations of the supernova SN 1993J at radio wavelengths make this object a unique target for the study of particle acceleration in a supernova shock. Methods: To describe the radio synchrotron emission we use a model that couples a semianalytic description of nonlinear diffusive shock acceleration with self-similar solutions for the hydrodynamics of the supernova expansion. The synchrotron emission, which is assumed to be produced by relativistic electrons propagating in the postshock plasma, is worked out from radiative transfer calculations that include the process of synchrotron self-absorption. The model is applied to explain the morphology of the radio emission deduced from high-resolution VLBI imaging observations and the measured time evolution of the total flux density at six frequencies. Results: Both the light curves and the morphology of the radio emission indicate that the magnetic field was strongly amplified in the blast wave region shortly after the explosion, possibly via the nonresonant regime of the cosmic-ray streaming instability operating in the shock precursor. The amplified magnetic field immediately upstream from the subshock is determined to be Bu ≈ 50 (t/1 { day})-1 G. The turbulent magnetic field was not damped behind the shock but carried along by the plasma flow in the downstream region. Cosmic-ray protons were efficiently produced by diffusive shock acceleration at the blast wave. We find that during the first 8.5 years after the explosion, about 19% of the total energy processed by the forward shock was converted to cosmic-ray energy. However, the shock remained weakly modified by the cosmic-ray pressure. The high magnetic field amplification implies that protons were rapidly accelerated to energies well above 1015 eV. The results obtained for this supernova support the scenario that massive stars exploding into their former stellar wind are a major source of Galactic cosmic-rays of energies above 1015 eV. We
Non-linear diffusion of cosmic rays escaping from supernova remnants - I. The effect of neutrals
NASA Astrophysics Data System (ADS)
Nava, L.; Gabici, S.; Marcowith, A.; Morlino, G.; Ptuskin, V. S.
2016-10-01
Supernova remnants are believed to be the main sources of galactic cosmic rays (CR). Within this framework, particles are accelerated at supernova remnant shocks and then released in the interstellar medium. The mechanism through which CRs are released and the way in which they propagate still remain open issues. The main difficulty is the high non-linearity of the problem: CRs themselves excite the magnetic turbulence that confines them close to their sources. We solve numerically the coupled differential equations describing the evolution in space and time of the escaping particles and of the waves generated through the CR streaming instability. The warm ionized and warm neutral phases of the interstellar medium are considered. These phases occupy the largest fraction of the disc volume, where most supernovae explode, and are characterized by the significant presence of neutral particles. The friction between those neutrals and ions results in a very effective wave damping mechanism. It is found that streaming instability affects the propagation of CRs even in the presence of ion-neutral friction. The diffusion coefficient can be suppressed by more than a factor of ˜2 over a region of few tens of pc around the remnant. The suppression increases for smaller distances. The propagation of ≈10 GeV particles is affected for several tens of kiloyears after escape, while ≈1 TeV particles are affected for few kiloyears. This might have a great impact on the interpretation of gamma-ray observations of molecular clouds located in the vicinity of supernova remnants.
NASA Astrophysics Data System (ADS)
Xia, Shaoyan; Huang, Yong; Tan, Xiaodi
2016-03-01
Partial differential equation (PDE)-based nonlinear diffusion processes have been widely used for image denoising. In the traditional nonlinear anisotropic diffusion denoising techniques, behavior of the diffusion depends highly on the gradient of image. However, it is difficult to get a good effect if we use these methods to reduce noise in optical coherence tomography images. Because background has the gradient that is very similar to regions of interest, so background noise will be mistaken for edge information and cannot be reduced. Therefore, nonlinear complex diffusion approaches using texture feature(NCDTF) for noise reduction in phase-resolved optical coherence tomography is proposed here, which uses texture feature in OCT images and structural OCT images to remove noise in phase-resolved OCT. Taking into account the fact that texture between background and signal region is different, which can be linked with diffusion coefficient of nonlinear complex diffusion model, we use NCDTF method to reduce noises of structure and phase images first. Then, we utilize OCT structure images to filter phase image in OCT. Finally, to validate our method, parameters such as image SNR, contrast-to-noise ratio (CNR), equivalent number of looks (ENL), and edge preservation were compared between our approach and median filter, Gaussian filter, wavelet filter, nonlinear complex diffusion filter (NCDF). Preliminary results demonstrate that NCDTF method is more effective than others in keeping edges and denoising for phase-resolved OCT.
Self-similar solutions of the non-linear diffusion equation and application to near-critical fluids
NASA Astrophysics Data System (ADS)
Fröhlich, T.; Bouquet, S.; Bonetti, M.; Garrabos, Y.; Beysens, D.
1995-02-01
We use analytic self-similar solutions of both the linear and non-linear diffusion equation to determine the behavior of a heat conducting system experiencing a time-dependent energy production. Supposing a power law evolution of the system parameters, we calculate the corresponding exponents to describe the temporal behavior of the system. In the non-linear case, we are able to introduce a variation of both the coefficient of diffusion and the amplitude of the heat source. The analytic solutions are checked numerically. These results can be considered, for example, as the basis for further developments on the non-linear behavior of supercritical fluids in a microgravity environment, e.g. the “Piston Effect” (M. Bonetti et al., Phys. Rev. E 49 (1994) 4779) or the “Jet Instability” (D. Beysens et al., Near-critical Fluids in Space, in: Lectures on Thermodynamics and Statistical Mechanics, M. Costas et al., eds. (World Scientific, Singapore, 1994) p. 88).
NASA Astrophysics Data System (ADS)
Liñares, J.; Sotelo, D.; Lipovskii, A. A.; Zhurihina, V. V.; Tagantsev, D. K.; Turunen, J.
2000-03-01
We have designed novel glasses for the formation of graded-index diffractive optical structures. In these glasses silver ion exchange and rapid diffusion produce a large refractive-index variation (0.085). We model the non-linearity of the diffusion process by applying the Boltzmann-Matano technique to the optical profiles and use index variation rather than concentration in the second Fick equation. The simulation of graded-index diffraction gratings formed under thermal and electrically assisted diffusion shows that, other conditions being equal, more efficient gratings can be formed when the diffusion coefficient increases with the dopant concentration. According to the simulation, the application of an electric field of about 0.5 V/μm enables one to obtain a phase shift equal to 1.5 π rad if a grating with a period of 4 μm is formed in the novel glass material. For comparison, a phase shift of only 0.9 π is predicted when a similar grating is formed in the commercial BK-7 glass.
Wang, Y.
2013-07-01
Nonlinear diffusion acceleration (NDA) can improve the performance of a neutron transport solver significantly especially for the multigroup eigenvalue problems. The high-order transport equation and the transport-corrected low-order diffusion equation form a nonlinear system in NDA, which can be solved via a Picard iteration. The consistency of the correction of the low-order equation is important to ensure the stabilization and effectiveness of the iteration. It also makes the low-order equation preserve the scalar flux of the high-order equation. In this paper, the consistent correction for a particular discretization scheme, self-adjoint angular flux (SAAF) formulation with discrete ordinates method (S{sub N}) and continuous finite element method (CFEM) is proposed for the multigroup neutron transport equation. Equations with the anisotropic scatterings and a void treatment are included. The Picard iteration with this scheme has been implemented and tested with RattleS{sub N}ake, a MOOSE-based application at INL. Convergence results are presented. (authors)
NASA Astrophysics Data System (ADS)
Tiguercha, Djlalli; Bennis, Anne-claire; Ezersky, Alexander
2015-04-01
The elliptical motion in surface waves causes an oscillating motion of the sand grains leading to the formation of ripple patterns on the bottom. Investigation how the grains with different properties are distributed inside the ripples is a difficult task because of the segration of particle. The work of Fernandez et al. (2003) was extended from one-dimensional to two-dimensional case. A new numerical model, based on these non-linear diffusion equations, was developed to simulate the grain distribution inside the marine sand ripples. The one and two-dimensional models are validated on several test cases where segregation appears. Starting from an homogeneous mixture of grains, the two-dimensional simulations demonstrate different segregation patterns: a) formation of zones with high concentration of light and heavy particles, b) formation of «cat's eye» patterns, c) appearance of inverse Brazil nut effect. Comparisons of numerical results with the new set of field data and wave flume experiments show that the two-dimensional non-linear diffusion equations allow us to reproduce qualitatively experimental results on particles segregation.
Nonlinear dynamics of hydrogen-air detonations with detailed kinetics and diffusion
NASA Astrophysics Data System (ADS)
Powers, Joseph; Romick, Christopher; Aslam, Tariq
2014-11-01
We consider the calculation of unsteady detonation in a mixture of calorically imperfect ideal gases with detailed kinetics. The use of detailed kinetics introduces multiple reaction length scales, and their interaction gives rise to complex dynamics. These are predicted using a wavelet-based adaptive mesh refinement technique and includes multi-component species, momentum, and energy diffusion, as well as DuFour and Soret effects. In the one-dimensional limit, we predict a transition from stability to unstable limit cycles as a driving piston velocity is lowered. At low overdrive, energy is partitioned into a variety of high frequency oscillatory modes. For weak low frequency instabilities, the dynamics are largely explained by a competition between advection and reaction time scales, with diffusion serving to perturb the dynamics. For higher frequency instabilities, the influence of diffusion is larger. We present new extensions to two-dimensional dynamics.
Ziegler, Ronny; Nielsen, Tim; Koehler, Thomas; Grosenick, Dirk; Steinkellner, Oliver; Hagen, Axel; Macdonald, Rainer; Rinneberg, Herbert
2009-08-20
We report on the nonlinear reconstruction of local absorption and fluorescence contrast in tissuelike scattering media from measured time-domain diffuse reflectance and transmittance of laser as well as laser-excited fluorescence radiation. Measurements were taken at selected source-detector offsets using slablike diffusely scattering and fluorescent phantoms containing fluorescent heterogeneities. Such measurements simulate in vivo data that would be obtained employing a scanning, time-domain fluorescence mammograph, where the breast is gently compressed between two parallel glass plates, and source and detector optical fibers scan synchronously at various source-detector offsets, allowing the recording of laser and fluorescence mammograms. The diffusion equations modeling the propagation of the laser and fluorescence radiation were solved in frequency domain by the finite element method simultaneously for several modulation frequencies using Fourier transformation and preprocessed experimental data. To reconstruct the concentration of the fluorescent contrast agent, the Born approximation including higher-order reconstructed photon densities at the excitation wavelength was used. Axial resolution was determined that can be achieved by various detection schemes. We show that remission measurements increase the depth resolution significantly.
NASA Astrophysics Data System (ADS)
Dikpati, Mausumi; Cally, Paul S.; Gilman, Peter A.
2004-07-01
We develop a more realistic two-dimensional model for global MHD instabilities in the solar tachocline, by including diffusion in the form of kinetic and magnetic drag (following Newton's cooling law formulation). This instability has previously been studied by us and others for an idealized tachocline with no kinematic viscosity and magnetic diffusivity. Since radial diffusion is more important than latitudinal diffusion in the thin solar tachocline, diffusive decay of flow and magnetic fields can be considered as proportional to those variables. We find that, for solar-like toroidal magnetic fields of ~100 kG, instability exists for a wide range of kinetic and magnetic drag parameters, providing a mechanism for enhanced angular momentum transport in latitudes, which could explain how thin the solar tachocline is. From a detailed parameter space survey, we set upper limits of 5×1011 and 3×1010 cm2 s-1 for kinematic viscosity and magnetic diffusivity, respectively, such that this instability occurs in the solar tachocline on a timescale shorter than a sunspot cycle. We find that magnetic drag has much more influence than kinetic drag in damping this instability. This happens because the sink due to magnetic drag dissipates perturbation magnetic energy faster than the vorticity sink from kinetic drag dissipates perturbation kinetic energy. Consequently, in the presence of a large enough magnetic drag, the nonsolar-like clamshell pattern, found by Cally to be an inevitable final state of a broad profile undergoing an ideal MHD tachocline instability, is suppressed, whereas a banded profile still tips with no reduction in tip angle. We discuss how tipping may affect various surface manifestations of magnetic features, such as the latitudes and orientations of bipolar active regions.
Turbulence Dissipation in Non-Linear Diffusive Shock Acceleration with Magnetic Field Amplification
NASA Astrophysics Data System (ADS)
Ellison, Donald C.; Vladimirov, A.
2008-03-01
High Mach number shocks in young supernova remnants (SNRs) are believed to simultaneously place a large fraction of the supernova explosion energy in relativistic particles and amplify the ambient magnetic field by large factors. Continuing our efforts to model this strongly nonlinear process with a Monte Carlo simulation, we have incorporated the effects of the dissipation of the self-generated turbulence on the shock structure and thermal particle injection rate. We find that the heating of the thermal gas in the upstream shock precursor by the turbulence damping significantly impacts the acceleration process in our thermal pool injection model. This precursor heating may also have observational consequences. In this preliminary work, we parameterize the turbulence damping rate and lay the groundwork for incorporating more realistic physical models of turbulence generation and dissipation in nonlinear DSA. This work was support in part by NASA ATP grant NNX07AG79G.
Comparison of Nonlinear and Linear Stabilization Schemes for Advection-Diffusion Equations
NASA Astrophysics Data System (ADS)
Grove, R. R.; Heister, T.
2015-12-01
Accurately solving advection-diffusion equations that appear in the finite element discretization of a mantle convection simulation is an important computational issue to the computational geoscience community. This is because it allows for users studying mantle convection to create reliable simulations for something as small and simple as a 2D simulation on their personal laptop to something as complex as a massively parallel 3D simulation on their university supercomputer. Standard finite element discretizations of advection-diffusion equations introduce unphysical oscillations around steep gradients. Therefore, stabilization must be added to the discrete formulation to obtain correct solutions. Using the open source scientific library ASPECT, the SUPG and Entropy Viscosity schemes are compared using stationary and non-stationary test equations. Differences in maximum overshoot and undershoot, smear, and convergence orders are compared to see if improvements can be made to the existing numerical method existing in ASPECT.
Reactive-Diffusive-Advective Traveling Waves in a Family of Degenerate Nonlinear Equations
Sánchez-Garduño, Faustino
2016-01-01
This paper deals with the analysis of existence of traveling wave solutions (TWS) for a diffusion-degenerate (at D(0) = 0) and advection-degenerate (at h′(0) = 0) reaction-diffusion-advection (RDA) equation. Diffusion is a strictly increasing function and the reaction term generalizes the kinetic part of the Fisher-KPP equation. We consider different forms of the convection term h(u): (1) h′(u) is constant k, (2) h′(u) = ku with k > 0, and (3) it is a quite general form which guarantees the degeneracy in the advective term. In Case 1, we prove that the task can be reduced to that for the corresponding equation, where k = 0, and then previous results reported from the authors can be extended. For the other two cases, we use both analytical and numerical tools. The analysis we carried out is based on the restatement of searching TWS for the full RDA equation into a two-dimensional dynamical problem. This consists of searching for the conditions on the parameter values for which there exist heteroclinic trajectories of the ordinary differential equations (ODE) system in the traveling wave coordinates. Throughout the paper we obtain the dynamics by using tools coming from qualitative theory of ODE.
Reactive-Diffusive-Advective Traveling Waves in a Family of Degenerate Nonlinear Equations
Sánchez-Garduño, Faustino
2016-01-01
This paper deals with the analysis of existence of traveling wave solutions (TWS) for a diffusion-degenerate (at D(0) = 0) and advection-degenerate (at h′(0) = 0) reaction-diffusion-advection (RDA) equation. Diffusion is a strictly increasing function and the reaction term generalizes the kinetic part of the Fisher-KPP equation. We consider different forms of the convection term h(u): (1) h′(u) is constant k, (2) h′(u) = ku with k > 0, and (3) it is a quite general form which guarantees the degeneracy in the advective term. In Case 1, we prove that the task can be reduced to that for the corresponding equation, where k = 0, and then previous results reported from the authors can be extended. For the other two cases, we use both analytical and numerical tools. The analysis we carried out is based on the restatement of searching TWS for the full RDA equation into a two-dimensional dynamical problem. This consists of searching for the conditions on the parameter values for which there exist heteroclinic trajectories of the ordinary differential equations (ODE) system in the traveling wave coordinates. Throughout the paper we obtain the dynamics by using tools coming from qualitative theory of ODE. PMID:27689131
NASA Astrophysics Data System (ADS)
Kang, Jinbum; Yoo, Yangmo
2014-03-01
Speckle, shown as a granular pattern, considerably degrades the image quality of ultrasound B-mode imaging and lowers the performance of image segmentation and registration techniques. Thus, speckle reduction while preserving the tissue structure (e.g., edges and boundaries of lesions) is important for ultrasound B-mode imaging. In this paper, a new approach for speckle reduction and edge enhancement based on laplacian pyramid nonlinear diffusion and homomorphic filtering (LPNDHF) is proposed for ultrasound B-mode imaging. In LPNDHF, nonlinear diffusion with a weighting factor is applied in multi-scale domain (i.e., laplacian pyramid) for effectively suppressing the speckle. In addition, in order to overcome the drawback from the previous LPND method, i.e., blurred edges, homomorphic filtering for edge and contrast enhancement is also applied from a finer scale to a coarser scale. From the simulation study, the proposed LPNDHF method showed the higher edge preservation and structure similarity values compared to the LPND and LPND with shock filtering (LPNDSF). Also, the LPNDHF provided the higher CNR values compared to LPND and LPNDSF, i.e., 5.02 vs. 3.66 and 2.91, respectively. From the tissue mimicking phantom study, the similar improvement in CNR was achieved from the LPNDHF over LPND and LPNDSF, i.e., 2.35 vs. 1.83 and 1.30. Moreover, the consistent results were obtained with the in vivo abdominal study. These preliminary results demonstrate that the proposed LPNDHF can improve the image quality of ultrasound B-mode imaging by increasing contrast and enhancing the specific signal details while effectively suppressing speckle.
NASA Astrophysics Data System (ADS)
Simmons, Alex; Yang, Qianqian; Moroney, Timothy
2015-04-01
The numerical solution of fractional partial differential equations poses significant computational challenges in regard to efficiency as a result of the spatial nonlocality of the fractional differential operators. The dense coefficient matrices that arise from spatial discretisation of these operators mean that even one-dimensional problems can be difficult to solve using standard methods on grids comprising thousands of nodes or more. In this work we address this issue of efficiency for one-dimensional, nonlinear space-fractional reaction-diffusion equations with fractional Laplacian operators. We apply variable-order, variable-stepsize backward differentiation formulas in a Jacobian-free Newton-Krylov framework to advance the solution in time. A key advantage of this approach is the elimination of any requirement to form the dense matrix representation of the fractional Laplacian operator. We show how a banded approximation to this matrix, which can be formed and factorised efficiently, can be used as part of an effective preconditioner that accelerates convergence of the Krylov subspace iterative solver. Our approach also captures the full contribution from the nonlinear reaction term in the preconditioner, which is crucial for problems that exhibit stiff reactions. Numerical examples are presented to illustrate the overall effectiveness of the solver.
Bykov, Andrei M.; Osipov, Sergei M.; Ellison, Donald C.; Vladimirov, Andrey E. E-mail: osm2004@mail.ru E-mail: avenovo@gmail.com
2014-07-10
We present a nonlinear Monte Carlo model of efficient diffusive shock acceleration where the magnetic turbulence responsible for particle diffusion is calculated self-consistently from the resonant cosmic-ray (CR) streaming instability, together with non-resonant short- and long-wavelength CR-current-driven instabilities. We include the backpressure from CRs interacting with the strongly amplified magnetic turbulence which decelerates and heats the super-Alfvénic flow in the extended shock precursor. Uniquely, in our plane-parallel, steady-state, multi-scale model, the full range of particles, from thermal (∼eV) injected at the viscous subshock to the escape of the highest energy CRs (∼PeV) from the shock precursor, are calculated consistently with the shock structure, precursor heating, magnetic field amplification, and scattering center drift relative to the background plasma. In addition, we show how the cascade of turbulence to shorter wavelengths influences the total shock compression, the downstream proton temperature, the magnetic fluctuation spectra, and accelerated particle spectra. A parameter survey is included where we vary shock parameters, the mode of magnetic turbulence generation, and turbulence cascading. From our survey results, we obtain scaling relations for the maximum particle momentum and amplified magnetic field as functions of shock speed, ambient density, and shock size.
The Doubly Exceptional Child: A Principal's Dilemma.
ERIC Educational Resources Information Center
Kesner, Rebecca J., Ed.
2002-01-01
This document contains two articles concerned with doubly exceptional children and gifted education. In "The Doubly Exceptional Child: A Principal's Dilemma," (Carol J. Mills and Linda E. Brody), such children do not fit into the usual categories for sorting children because their gifts and disabilities often mask each other. Suggestions are…
NASA Astrophysics Data System (ADS)
Vlad, Marcel Ovidiu; Moran, Federico; Tsuchiya, Masa; Cavalli-Sforza, L. Luca; Oefner, Peter J.; Ross, John
2002-06-01
We study a general class of nonlinear macroscopic evolution equations with ``transport'' and ``reaction'' terms which describe the dynamics of a species of moving individuals (atoms, molecules, quasiparticles, organisms, etc.). We consider that two types of individuals exist, ``not marked'' and ``marked,'' respectively. We assume that the concentrations of both types of individuals are measurable and that they obey a neutrality condition, that is, the kinetic and transport properties of the ``not marked'' and ``marked'' individuals are identical. We suggest a response experiment, which consists in varying the fraction of ``marked'' individuals with the preservation of total fluxes, and show that the response of the system can be represented by a linear superposition law even though the underlying dynamics of the system is in general highly nonlinear. The linear response law is valid even for large perturbations and is not the result of a linearization procedure but rather a necessary consequence of the neutrality condition. First, we apply the response theorem to chemical kinetics, where the ``marked species'' is a molecule labeled with a radioactive isotope and there is no kinetic isotope effect. The susceptibility function of the response law can be related to the reaction mechanism of the process. Secondly we study the geographical distribution of the nonrecurrent, nonreversible neutral mutations of the nonrecombining portion of the Y chromosome from human populations and show that the fraction of mutants at a given point in space and time obeys a linear response law of the type introduced in this paper. The theory may be used for evaluating the geographic position and the moment in time where and when a mutation originated.
NASA Astrophysics Data System (ADS)
Watkins, N. W.; Credgington, D.; Sanchez, R.; Chapman, S. C.
2007-12-01
Since the 1960s Mandelbrot has advocated the use of fractals for the description of the non-Euclidean geometry of many aspects of nature. In particular he proposed two kinds of model to capture persistence in time (his Joseph effect, common in hydrology and with fractional Brownian motion as the prototpe) and/or prone to heavy tailed jumps (the Noah effect, typical of economic indices, for which he proposed Lévy flights as an exemplar). Both effects are now well demonstrated in space plasmas, notably in indices quantifying Earth's auroral currents and in the turbulent solar wind. Models have, however, typically emphasised one of the Noah and Joseph parameters (the Lévy exponent μ and the temporal exponent β) at the other's expense. I will describe recent work [1] in which we studied a simple self-affine stable model-linear fractional stable motion, LFSM, which unifies both effects. I will discuss how this resolves some contradictions seen in earlier work. Such Noah-Joseph hybrid ("ambivalent" [2]) behaviour is highly topical in physics but is typically studied in the paradigm of the continuous time random walk (CTRW) [2,3] rather than LFSM. I will clarify the physical differences between these two pictures and present a recently-derived diffusion equation for LFSM. This replaces the second order spatial derivative in the equation of fBm [4] with a fractional derivative of order μ, but retains a diffusion coefficient with a power law time dependence rather than a fractional derivative in time (c.f. [2,3]). Intriguingly the self-similarity exponent extracted from the CTRW differs from that seen in LFSM. In the CTRW it is the ratio of μ to a temporal exponent, in LFSM it is an additive function of them. I will also show work in progress using an LFSM model and simple analytic scaling arguments to study the problem of the area between an LFSM curve and a threshold-related to the burst size measure introduced by Takalo and Consolini into solar- terrestrial physics
NASA Astrophysics Data System (ADS)
Marino, B. M.; Thomas, L. P.; Gratton, R.; Diez, J. A.; Betelú, S.; Gratton, J.
1996-09-01
We investigate an unsteady plane viscous gravity current of silicone oil on a horizontal glass substrate. Within the lubrication approximation with gravity as the dominant force, this current is described by the nonlinear diffusion equation φt=(φmφx)x (φ is proportional to the liquid thickness h and m=3>0), which is of interest in many other physical processes. The solutions of this equation display a fine example of the competition between diffusive smoothening and nonlinear steepening. This work concerns the so-called waiting-time solutions, whose distinctive character is the presence of an interface or front, separating regions with h≠/0 and h=0, that remains motionless for a finite time interval tw meanwhile a redistribution of h takes place behind the interface. We start the experiments from an initial wedge-shape configuration [h(x)~=α'(x0-x)] with a small angle (α'<=0.12 rad). In this situation, the tip of the wedge, situated at x0 from the rear wall (15 cm<=x0<=75 cm), waits at least several seconds before moving. During this waiting stage, a region characterized by a strong variation of the free surface slope (corner layer) develops and propagates toward the front while it gradually narrows and ∂2h/∂x2 peaks. The stage ends when the corner layer overtakes the front. At this point, the liquid begins to spread over the uncovered substrate. We measure the slope of the free surface in a range ~=10 cm around x0, and, by integration, we determine the fluid thickness h(x) there. We find that the flow tends to a self-similar behavior when the corner layer position tends to x0; however, near the end of the waiting stage, it is perturbed by capillarity. Even if some significant effects are not included in the above equation, the main properties of its solutions are well displayed in the experiments
Doubly Excited States in Be III
NASA Astrophysics Data System (ADS)
Andersen, T.; Bentzen, S. M.; Poulsen, O.
1980-01-01
The triplet spectrum of doubly excited Be III has been studied in the wavelength region of 75-5000 Å in order to test the validity of the theoretical term values reported by Lipsky et al. The beam-foil excitation technique was applied to effectively populate the doubly excited states. The identified lower-lying, doubly excited states 2p2 3P, 2pnp 3P, or 3D, and 2pnd 3P, or 3D (n = 3, 4) show that the theoretical term values should be slightly modified.
Wei, Jingsong; Wang, Rui
2014-03-28
In this work, the resolving limit of maskless direct laser writing is overcome by cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion, where the nonlinear reverse saturation absorption can induce the formation of below diffraction-limited energy absorption spot, and the thermal diffusion manipulation can make the heat quantity at the central region of energy absorption spot propagate along the thin film thickness direction. The temperature at the central region of energy absorption spot transiently reaches up to melting point and realizes nanolithography. The sample “glass substrate/AgInSbTe” is prepared, where AgInSbTe is taken as nonlinear reverse saturation absorption thin film. The below diffraction-limited energy absorption spot is simulated theoretically and verified experimentally by near-field spot scanning method. The “glass substrate/Al/AgInSbTe” sample is prepared, where the Al is used as thermal conductive layer to manipulate the thermal diffusion channel because the thermal diffusivity coefficient of Al is much larger than that of AgInSbTe. The direct laser writing is conducted by a setup with a laser wavelength of 650 nm and a converging lens of NA=0.85, the lithographic marks with a size of about 100 nm are obtained, and the size is only about 1/10 the incident focused spot. The experimental results indicate that the cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion is a good method to realize nanolithography in maskless direct laser writing with visible light.
Elton, A.B.H.
1990-09-24
A numerical theory for the massively parallel lattice gas and lattice Boltzmann methods for computing solutions to nonlinear advective-diffusive systems is introduced. The convergence theory is based on consistency and stability arguments that are supported by the discrete Chapman-Enskog expansion (for consistency) and conditions of monotonicity (in establishing stability). The theory is applied to four lattice methods: Two of the methods are for some two-dimensional nonlinear diffusion equations. One of the methods is for the one-dimensional lattice method for the one-dimensional viscous Burgers equation. And one of the methods is for a two-dimensional nonlinear advection-diffusion equation. Convergence is formally proven in the L{sub 1}-norm for the first three methods, revealing that they are second-order, conservative, conditionally monotone finite difference methods. Computational results which support the theory for lattice methods are presented. In addition, a domain decomposition strategy using mesh refinement techniques is presented for lattice gas and lattice Boltzmann methods. The strategy allows concentration of computational resources on regions of high activity. Computational evidence is reported for the strategy applied to the lattice gas method for the one-dimensional viscous Burgers equation. 72 refs., 19 figs., 28 tabs.
Bondar, I. I. Suran, V. V.; Bondar, D. I.
2013-06-15
The formation of singly and doubly charged ions upon nonlinear ionization of barium atoms is studied as a function of the frequency and intensity of a 8800-8920-cm{sup -1} IR color center laser. Barium atoms are ionized via the four-photon resonance with the strongly perturbed bound 6p{sup 21}D{sub 2} state. Doubly charged barium ions are produced by a two-electron mechanism. It is found that the probability of the formation of doubly charged ions under these conditions linearly depends on the laser radiation intensity.
Isospin Splittings of Doubly Heavy Baryons
Brodsky, Stanley J.; Guo, Feng-Kun; Hanhart, Christoph; Meissner, Ulf-G.; /Julich, Forschungszentrum /JCHP, Julich /IAS, Julich /Bonn U., HISKP /Bonn U.
2011-08-18
The SELEX Collaboration has reported a very large isospin splitting of doubly charmed baryons. We show that this effect would imply that the doubly charmed baryons are very compact. One intriguing possibility is that such baryons have a linear geometry Q-q-Q where the light quark q oscillates between the two heavy quarks Q, analogous to a linear molecule such as carbon dioxide. However, using conventional arguments, the size of a heavy-light hadron is expected to be around 0.5 fm, much larger than the size needed to explain the observed large isospin splitting. Assuming the distance between two heavy quarks is much smaller than that between the light quark and a heavy one, the doubly heavy baryons are related to the heavy mesons via heavy quark-diquark symmetry. Based on this symmetry, we predict the isospin splittings for doubly heavy baryons including {Xi}{sub cc}, {Xi}{sub bb} and {Xi}{sub bc}. The prediction for the {Xi}{sub cc} is much smaller than the SELEX value. On the other hand, the {Xi}{sub bb} baryons are predicted to have an isospin splitting as large as (6.3 {+-} 1.7) MeV. An experimental study of doubly bottomed baryons is therefore very important to better understand the structure of baryons with heavy quarks.
Doubly fed machine review: agenda. Conference report, Washington, DC
Not Available
1982-09-01
The visual aids presented at the doubly fed machine review are presented. The doubly fed machine is a generating system either for wind turbines or hydro systems. Conceptual design and trade-offs are included, as well as testing. (LEW)
NASA Technical Reports Server (NTRS)
Goldstein, M. L.
1977-01-01
In a study of cosmic ray propagation in interstellar and interplanetary space, a perturbed orbit resonant scattering theory for pitch angle diffusion in a slab model of magnetostatic turbulence is slightly generalized and used to compute the diffusion coefficient for spatial propagation parallel to the mean magnetic field. This diffusion coefficient has been useful for describing the solar modulation of the galactic cosmic rays, and for explaining the diffusive phase in solar flares in which the initial anisotropy of the particle distribution decays to isotropy.
NASA Astrophysics Data System (ADS)
Sunil; Mahajan, Amit
2009-09-01
A rigorous nonlinear stability result is derived by introducing a suitable generalized energy functional for a magnetized ferrofluid layer heated and soluted from below with magnetic field-dependent (MFD) viscosity, for stress-free boundaries. The mathematical emphasis is on how to control the nonlinear terms caused by magnetic body and inertia forces. For ferrofluids, we find that there is possibility of existence of subcritical instabilities, however, it is noted that in case of non-ferrofluid, global nonlinear stability Rayleigh number is exactly the same as that for linear instability. For lower values of magnetic parameters, this coincidence is immediately lost. The effects of magnetic parameter, M3, solute gradient, S1 and MFD viscosity parameter, δ, on the subcritical instability region have also been analyzed.
NASA Astrophysics Data System (ADS)
Langenbruch, C.
2015-12-01
In August 2014 segmented lateral dyke growth has been observed in a rifting event at Bardarbunga volcanic system, Iceland. The temporal evolution of the magma source and the physical nature of magma flow process during dyke propagation and arrest are unclear. The epidemic-type aftershock sequence model has been used to detect fluid signals in seismicity data. We use the earthquake catalog recorded during the rifting event to reconstruct the magma flow signal at the feeding source of the dyke. We find that the segmentation of dyke growth is caused by a pulsating nature of the magma flow source. We identify two main magma flow pulses, which initiate and propagate the two main segments of the dyke. During phases of dyke arrest magma flow pulses are low and cannot further propagate the dyke. We use the reconstructed magma flow signal to set up a numerical model of non-linear magma pressure diffusion. By using the magma pressure changes resulting from magma flow, we simulate the earthquake catalog caused by the reduction of the effective principal stress. We observe an excellent agreement between the spatio-temporal characteristics of the simulated earthquake catalog and recorded seismicity. Our results suggest that the process of magma pressure relaxation can be described as a non-linear diffusion process. Because the opening of the dyke creates significant new fracture volume, the permeability of the rock is strongly increasing and the diffusion process becomes highly non-linear. Our analysis is based on lessons learned from analysis of seismicity observed during hydraulic fracturing of hydrocarbon reservoirs. Despite large differences in scale, the underlying physical processes are comparable. Finally, we analyze the decay of seismic activity after start of the effusive fissure eruption near the end of the dyke. The magma flow strongly decreases and seismic activity decays according to Omori's law, which describes the decay of aftershock activity after tectonic
Microwave Measurements of Maleimide and its Doubly Hydrogen Bonded Dimer with Formic ACID*
NASA Astrophysics Data System (ADS)
Pejlovas, Aaron M.; Kang, Lu; Kukolich, Stephen G.
2016-06-01
The microwave spectra were measured for the maleimide monomer and the maleimide-formic acid doubly hydrogen bonded dimer using a pulsed-beam Fourier transform microwave spectrometer. Many previously studied doubly hydrogen bonded dimers are formed between oxygen containing species, so it is important to also characterize and study other dimers containing nitrogen, as hydrogen bonding interactions with nitrogen are found in biological systems such as in DNA. The transition state of the dimer does not exhibit C_2_V symmetry, so the tunneling motion was not expected to be observed based on the symmetry, but it would be very important to also observe the tunneling process for an asymmetric dimer. Single-line b-type transitions were observed, so the tunneling motion was not observed in our microwave spectra. The hydrogen bond lengths were determined using a nonlinear least squares fitting program. *Supported by the NSF CHE-1057796
NASA Astrophysics Data System (ADS)
Williams, R. T.; Grim, Joel Q.; Li, Qi; Ucer, K. B.; Bizarri, G. A.; Kerisit, S.; Gao, Fei; Bhattacharya, P.; Tupitsyn, E.; Rowe, E.; Buliga, V. M.; Burger, A.
2013-09-01
Models of nonproportional response in scintillators have highlighted the importance of parameters such as branching ratios, carrier thermalization times, diffusion, kinetic order of quenching, associated rate constants, and radius of the electron track. For example, the fraction ηeh of excitations that are free carriers versus excitons was shown by Payne and coworkers to have strong correlation with the shape of electron energy response curves from Compton-coincidence studies. Rate constants for nonlinear quenching are implicit in almost all models of nonproportionality, and some assumption about track radius must invariably be made if one is to relate linear energy deposition dE/dx to volume-based excitation density n (eh/cm3) in terms of which the rates are defined. Diffusion, affecting time-dependent track radius and thus density of excitations, has been implicated as an important factor in nonlinear light yield. Several groups have recently highlighted diffusion of hot electrons in addition to thermalized carriers and excitons in scintillators. However, experimental determination of many of these parameters in the insulating crystals used as scintillators has seemed difficult. Subpicosecond laser techniques including interband z scan light yield, fluence-dependent decay time, and transient optical absorption are now yielding experimental values for some of the missing rates and ratios needed for modeling scintillator response. First principles calculations and Monte Carlo simulations can fill in additional parameters still unavailable from experiment. As a result, quantitative modeling of scintillator electron energy response from independently determined material parameters is becoming possible on an increasingly firmer data base. This paper describes recent laser experiments, calculations, and numerical modeling of scintillator response.
Doubly excited states in some light atoms
Berry, H.G.; Brooks, R.L.; Hardis, J.E.; Ray, W.J.
1981-01-01
We have identified a singlet transition in doubly excited helium: 2p/sup 2/ /sup 1/D - 2p3d /sup 1/D, at 3298 +- 2A with a full width of 54A or 0.061 +- 0.005 eV. This width is in good agreement with a previous measurement and theory for the width of the 2p/sup 2/ /sup 1/D/sub 2/ state. We have remeasured the decay rate of 1s/sup 2/2p/sup 2/P - 1s2p/sup 2/ /sup 2/P in Li I and find it is in good agreement with theory. Several transitions in doubly excited Li II have been identified in the 1000A region. No evidence was found for doubly excited quartet transitions in Li I in the vacuum ultraviolet. We present measurements of wavelengths and fine structure of the 1s2s2p/sup 2/ /sup 5/P - 1s2p/sup 3/ /sup 5/S transitions in C III, N IV and O V.
NASA Astrophysics Data System (ADS)
Kawai, Yusuke; Yamada, Yoshio
2016-07-01
This paper deals with a free boundary problem for diffusion equation with a certain class of bistable nonlinearity which allows two positive stable equilibrium states as an ODE model. This problem models the invasion of a biological species and the free boundary represents the spreading front of its habitat. Our main interest is to study large-time behaviors of solutions for the free boundary problem. We will completely classify asymptotic behaviors of solutions and, in particular, observe two different types of spreading phenomena corresponding to two positive stable equilibrium states. Moreover, it will be proved that, if the free boundary expands to infinity, an asymptotic speed of the moving free boundary for large time can be uniquely determined from the related semi-wave problem.
Keyes, Joseph T.; Simon, Bruce R.; Vande Geest, Jonathan P.
2013-01-01
Purpose Arterial wall mass transport properties dictate local distribution of biomolecules or locally delivered dugs. Knowing how these properties vary between coronary artery locations could provide insight into how therapy efficacy is altered between arterial locations. Methods We introduced an indocarbocyanine drug surrogate to the lumens of left anterior descending and right coronary (LADC; RC) arteries from pigs with or without a pressure gradient. Interstitial fluorescent intensity was measured on live samples with multiphoton microscopy. We also measured binding to porcine coronary SMCs in monoculture. Results Diffusive transport constants peaked in the middle sections of the LADC and RC arteries by 2.09 and 2.04 times, respectively, compared to the proximal and distal segments. There was no statistical difference between the average diffusivity value between LADC and RC arteries. The convection coefficients had an upward trend down each artery, with the RC being higher than the LADC by 3.89 times. Conclusions This study demonstrates that the convective and diffusive transport of lipophilic molecules changes between the LADC and the RC arteries as well as along their length. These results may have important implications in optimizing drug delivery for the treatment of coronary artery disease. PMID:23224981
ERIC Educational Resources Information Center
Seider, Warren D.; Ungar, Lyle H.
1987-01-01
Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…
Sabelnikov, V A; Lipatnikov, A N
2014-09-01
The problem of traveling wave (TW) speed selection for solutions to a generalized Murray-Burgers-KPP-Fisher parabolic equation with a strictly positive cubic reaction term is considered theoretically and the initial boundary value problem is numerically solved in order to support obtained analytical results. Depending on the magnitude of a parameter inherent in the reaction term (i) the term is either a concave function or a function with the inflection point and (ii) transition from pulled to pushed TW solution occurs due to interplay of two nonlinear terms; the reaction term and the Burgers convection term. Explicit pushed TW solutions are derived. It is shown that physically observable TW solutions, i.e., solutions obtained by solving the initial boundary value problem with a sufficiently steep initial condition, can be determined by seeking the TW solution characterized by the maximum decay rate at its leading edge. In the Appendix, the developed approach is applied to a non-linear diffusion-reaction equation that is widely used to model premixed turbulent combustion.
Yu, Guang Tao; Chen, Wei; Gu, Feng Long; Aoki, Yuriko
2010-03-01
The static (hyper)polarizabilities of the dimer and trimer with diffuse excess electrons, [Li(+)[calix[4]pyrrole]Li(-)](n), are firstly investigated by the DFT(B3LYP) method in detail. For the dimer and trimer, a Li atom inside each calix[4]pyrrole unit is ionized to form a diffuse excess electron. The results show that the dimer and trimer containing two and three excess electrons, respectively, have very large first hyperpolarizablities as 2.3 x 10(4) and 4.0 x 10(4) au, which are 30 and 40 times larger than that of the corresponding [calix[4]pyrrole](n) (n = 2, 3) without Li atom. Also, beta values of dimer and trimer are twice and four times as large as that of monomer containing one excess electron. Obviously, not only excess electron but also the number of excess electron plays an important role in increasing the first hyperpolarizability. Moreover, the (hyper)polarizabilities of the [Li(+)[calix[4]pyrrole]Li(-)](n) polymer are investigated at ab initio level by using the elongation finite-field (elongation FF) method. All the oligomers of the [Li(+)[calix[4]pyrrole]Li(-)](n) with many excess electrons exhibit very large first hyperpolarizability and large second hyperpolarizability. The present investigation shows that by introducing several and more excess electrons into the nonlinear optical (NLO) materials will be an important strategy for improving their NLO properties, which will be helpful for design of NLO materials.
Barber, Jared; Tanase, Roxana; Yotov, Ivan
2016-06-01
Several Kalman filter algorithms are presented for data assimilation and parameter estimation for a nonlinear diffusion model of epithelial cell migration. These include the ensemble Kalman filter with Monte Carlo sampling and a stochastic collocation (SC) Kalman filter with structured sampling. Further, two types of noise are considered -uncorrelated noise resulting in one stochastic dimension for each element of the spatial grid and correlated noise parameterized by the Karhunen-Loeve (KL) expansion resulting in one stochastic dimension for each KL term. The efficiency and accuracy of the four methods are investigated for two cases with synthetic data with and without noise, as well as data from a laboratory experiment. While it is observed that all algorithms perform reasonably well in matching the target solution and estimating the diffusion coefficient and the growth rate, it is illustrated that the algorithms that employ SC and KL expansion are computationally more efficient, as they require fewer ensemble members for comparable accuracy. In the case of SC methods, this is due to improved approximation in stochastic space compared to Monte Carlo sampling. In the case of KL methods, the parameterization of the noise results in a stochastic space of smaller dimension. The most efficient method is the one combining SC and KL expansion. PMID:27085426
Barber, Jared; Tanase, Roxana; Yotov, Ivan
2016-06-01
Several Kalman filter algorithms are presented for data assimilation and parameter estimation for a nonlinear diffusion model of epithelial cell migration. These include the ensemble Kalman filter with Monte Carlo sampling and a stochastic collocation (SC) Kalman filter with structured sampling. Further, two types of noise are considered -uncorrelated noise resulting in one stochastic dimension for each element of the spatial grid and correlated noise parameterized by the Karhunen-Loeve (KL) expansion resulting in one stochastic dimension for each KL term. The efficiency and accuracy of the four methods are investigated for two cases with synthetic data with and without noise, as well as data from a laboratory experiment. While it is observed that all algorithms perform reasonably well in matching the target solution and estimating the diffusion coefficient and the growth rate, it is illustrated that the algorithms that employ SC and KL expansion are computationally more efficient, as they require fewer ensemble members for comparable accuracy. In the case of SC methods, this is due to improved approximation in stochastic space compared to Monte Carlo sampling. In the case of KL methods, the parameterization of the noise results in a stochastic space of smaller dimension. The most efficient method is the one combining SC and KL expansion.
Evidence for a doubly magic 24O
NASA Astrophysics Data System (ADS)
Hoffman, C. R.; Baumann, T.; Bazin, D.; Brown, J.; Christian, G.; Denby, D. H.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Hinnefeld, J.; Mosby, S.; Peters, W. A.; Rogers, W. F.; Schiller, A.; Spyrou, A.; Scott, M. J.; Tabor, S. L.; Thoennessen, M.; Voss, P.
2009-02-01
The decay energy spectrum for neutron unbound states in 24O ( Z=8, N=16) has been observed for the first time. The resonance energy of the lowest lying state, interpreted as the 2 level, has been observed at a decay energy above 600 keV. The resulting excitation energy of the 2 level above 4.7 MeV, supplies strong evidence that 24O is a doubly magic nucleus. The data is also consistent with the presence of a second excited state around 5.33 MeV which can be interpreted as the 1 level.
Burger, Karin; Koehler, Thomas; Chabior, Michael; Allner, Sebastian; Marschner, Mathias; Fehringer, Andreas; Willner, Marian; Pfeiffer, Franz; Noël, Peter
2014-12-29
Phase-contrast x-ray computed tomography has a high potential to become clinically implemented because of its complementarity to conventional absorption-contrast.In this study, we investigate noise-reducing but resolution-preserving analytical reconstruction methods to improve differential phase-contrast imaging. We apply the non-linear Perona-Malik filter on phase-contrast data prior or post filtered backprojected reconstruction. Secondly, the Hilbert kernel is replaced by regularized iterative integration followed by ramp filtered backprojection as used for absorption-contrast imaging. Combining the Perona-Malik filter with this integration algorithm allows to successfully reveal relevant sample features, quantitatively confirmed by significantly increased structural similarity indices and contrast-to-noise ratios. With this concept, phase-contrast imaging can be performed at considerably lower dose.
Samet Y. Kadioglu; Robert R. Nourgaliev; Vincent A. Mousseau
2008-03-01
We perform a comparative study for the harmonic versus arithmetic averaging of the heat conduction coefficient when solving non-linear heat transfer problems. In literature, the harmonic average is the method of choice, because it is widely believed that the harmonic average is more accurate model. However, our analysis reveals that this is not necessarily true. For instance, we show a case in which the harmonic average is less accurate when a coarser mesh is used. More importantly, we demonstrated that if the boundary layers are finely resolved, then the harmonic and arithmetic averaging techniques are identical in the truncation error sense. Our analysis further reveals that the accuracy of these two techniques depends on how the physical problem is modeled.
NASA Technical Reports Server (NTRS)
Goldstein, M. L.
1976-01-01
The propagation of charged particles through interstellar and interplanetary space has often been described as a random process in which the particles are scattered by ambient electromagnetic turbulence. In general, this changes both the magnitude and direction of the particles' momentum. Some situations for which scattering in direction (pitch angle) is of primary interest were studied. A perturbed orbit, resonant scattering theory for pitch-angle diffusion in magnetostatic turbulence was slightly generalized and then utilized to compute the diffusion coefficient for spatial propagation parallel to the mean magnetic field, Kappa. All divergences inherent in the quasilinear formalism when the power spectrum of the fluctuation field falls off as K to the minus Q power (Q less than 2) were removed. Various methods of computing Kappa were compared and limits on the validity of the theory discussed. For Q less than 1 or 2, the various methods give roughly comparable values of Kappa, but use of perturbed orbits systematically results in a somewhat smaller Kappa than can be obtained from quasilinear theory.
Designing and modeling doubly porous polymeric materials
NASA Astrophysics Data System (ADS)
Ly, H.-B.; Le Droumaguet, B.; Monchiet, V.; Grande, D.
2015-07-01
Doubly porous organic materials based on poly(2-hydroxyethyl methacrylate) are synthetized through the use of two distinct types of porogen templates, namely a macroporogen and a nanoporogen. Two complementary strategies are implemented by using either sodium chloride particles or fused poly(methyl methacrylate) beads as macroporogens, in conjunction with ethanol as a porogenic solvent. The porogen removal respectively allows for the generation of either non-interconnected or interconnected macropores with an average diameter of about 100-200 μm and nanopores with sizes lying within the 100 nm order of magnitude, as evidenced by mercury intrusion porosimetry and scanning electron microscopy. Nitrogen sorption measurements evidence the formation of materials with rather high specific surface areas, i.e. higher than 140 m2.g-1. This paper also addresses the development of numerical tools for computing the permeability of such doubly porous materials. Due to the coexistence of well separated scales between nanopores and macropores, a consecutive double homogenization approach is proposed. A nanoscopic scale and a mesoscopic scale are introduced, and the flow is evaluated by means of the Finite Element Method to determine the macroscopic permeability. At the nanoscopic scale, the flow is described by the Stokes equations with an adherence condition at the solid surface. At the mesoscopic scale, the flow obeys the Stokes equations in the macropores and the Darcy equation in the permeable polymer in order to account for the presence of the nanopores.
Double photoionization of doubly-excited lithium
NASA Astrophysics Data System (ADS)
Armstrong, G.; Pindzola, M. S.; Kheifets, A.; Schuricke, M.; Veeravalli, G.; Dornes, Ch.; Zhu, G.; Joachimsmeyer, K.; Treusch, R.; Dorn, A.; Colgan, J.
2012-06-01
We present triple differential cross sections and recoil ion momentum distributions for double photoionization of the 1s2s2p state of lithium. Double ionization of lithium may be treated as a two-active-electron process, where the ``active'' 2s and 2p electrons move in the field of the ``frozen-core'' Li^2+ 1s state.The time-dependent close-coupling (TDCC) method is used to solve the two-electron time-dependent Schr"odinger equation in full dimensionality. This work is motivated by recent FLASH experiments, which have obtained recoil-ion momentum distributions at a photon energy of 59 eV, where the 1s2s2p state is first reached via a 1s-2p photoexcitation from the initial ground state, and may then be doubly-ionized after the absorption of a second photon. The TDCC calculations in this work treat the subsequent photoionization of this doubly-excited state. The results are compared to those obtained by the convergent close-coupling method and to measurement, and provide a first comparison between theory and experiment in this fundamental few-photon few-body problem.
Banerjee, Tanmoy; Biswas, Debabrata
2013-12-01
We explore and experimentally demonstrate the phenomena of amplitude death (AD) and the corresponding transitions through synchronized states that lead to AD in coupled intrinsic time-delayed hyperchaotic oscillators interacting through mean-field diffusion. We identify a novel synchronization transition scenario leading to AD, namely transitions among AD, generalized anticipatory synchronization (GAS), complete synchronization (CS), and generalized lag synchronization (GLS). This transition is mediated by variation of the difference of intrinsic time-delays associated with the individual systems and has no analogue in non-delayed systems or coupled oscillators with coupling time-delay. We further show that, for equal intrinsic time-delays, increasing coupling strength results in a transition from the unsynchronized state to AD state via in-phase (complete) synchronized states. Using Krasovskii-Lyapunov theory, we derive the stability conditions that predict the parametric region of occurrence of GAS, GLS, and CS; also, using a linear stability analysis, we derive the condition of occurrence of AD. We use the error function of proper synchronization manifold and a modified form of the similarity function to provide the quantitative support to GLS and GAS. We demonstrate all the scenarios in an electronic circuit experiment; the experimental time-series, phase-plane plots, and generalized autocorrelation function computed from the experimental time series data are used to confirm the occurrence of all the phenomena in the coupled oscillators.
NASA Astrophysics Data System (ADS)
Banerjee, Tanmoy; Biswas, Debabrata
2013-12-01
We explore and experimentally demonstrate the phenomena of amplitude death (AD) and the corresponding transitions through synchronized states that lead to AD in coupled intrinsic time-delayed hyperchaotic oscillators interacting through mean-field diffusion. We identify a novel synchronization transition scenario leading to AD, namely transitions among AD, generalized anticipatory synchronization (GAS), complete synchronization (CS), and generalized lag synchronization (GLS). This transition is mediated by variation of the difference of intrinsic time-delays associated with the individual systems and has no analogue in non-delayed systems or coupled oscillators with coupling time-delay. We further show that, for equal intrinsic time-delays, increasing coupling strength results in a transition from the unsynchronized state to AD state via in-phase (complete) synchronized states. Using Krasovskii-Lyapunov theory, we derive the stability conditions that predict the parametric region of occurrence of GAS, GLS, and CS; also, using a linear stability analysis, we derive the condition of occurrence of AD. We use the error function of proper synchronization manifold and a modified form of the similarity function to provide the quantitative support to GLS and GAS. We demonstrate all the scenarios in an electronic circuit experiment; the experimental time-series, phase-plane plots, and generalized autocorrelation function computed from the experimental time series data are used to confirm the occurrence of all the phenomena in the coupled oscillators.
Search for the doubly charmed baryon
NASA Astrophysics Data System (ADS)
Aaij, R.; Adeva, B.; Adinolfi, M.; Adrover, C.; Affolder, A.; Ajaltouni, Z.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; Anderlini, L.; Anderson, J.; Andreassen, R.; Andrews, J. E.; Appleby, R. B.; Aquines Gutierrez, O.; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Balagura, V.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Bauer, Th.; Bay, A.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Belogurov, S.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bettler, M.-O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Bird, T.; Bizzeti, A.; Bjørnstad, P. M.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Brambach, T.; van den Brand, J.; Bressieux, J.; Brett, D.; Britsch, M.; Britton, T.; Brook, N. H.; Brown, H.; Bursche, A.; Busetto, G.; Buytaert, J.; Cadeddu, S.; Callot, O.; Calvi, M.; Calvo Gomez, M.; Camboni, A.; Campana, P.; Campora Perez, D.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carranza-Mejia, H.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Castillo Garcia, L.; Cattaneo, M.; Cauet, Ch.; Cenci, R.; Charles, M.; Charpentier, Ph.; Cheung, S.-F.; Chiapolini, N.; Chrzaszcz, M.; Ciba, K.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coca, C.; Coco, V.; Cogan, J.; Cogneras, E.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Cruz Torres, M.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; David, P.; David, P. N. Y.; Davis, A.; De Bonis, I.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Silva, W.; De Simone, P.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Déléage, N.; Derkach, D.; Deschamps, O.; Dettori, F.; Di Canto, A.; Dijkstra, H.; Dogaru, M.; Donleavy, S.; Dordei, F.; Dosil Suárez, A.; Dossett, D.; Dovbnya, A.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; van Eijk, D.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Falabella, A.; Färber, C.; Farinelli, C.; Farry, S.; Ferguson, D.; Fernandez Albor, V.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fitzpatrick, C.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gandelman, M.; Gandini, P.; Gao, Y.; Garofoli, J.; Garosi, P.; Garra Tico, J.; Garrido, L.; Gaspar, C.; Gauld, R.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gibson, V.; Giubega, L.; Gligorov, V. V.; Göbel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gorbounov, P.; Gordon, H.; Grabalosa Gándara, M.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Grünberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Hampson, T.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; Hartmann, T.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Hernando Morata, J. A.; van Herwijnen, E.; Heß, M.; Hicheur, A.; Hicks, E.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Hunt, P.; Huse, T.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Iakovenko, V.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jans, E.; Jaton, P.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Kaballo, M.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Kenyon, I. R.; Ketel, T.; Khanji, B.; Kochebina, O.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Korolev, M.; Kozlinskiy, A.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kucharczyk, M.; Kudryavtsev, V.; Kurek, K.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lambert, R. W.; Lanciotti, E.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J.-P.; Lefèvre, R.; Leflat, A.; Lefrançois, J.; Leo, S.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Li Gioi, L.; Liles, M.; Lindner, R.; Linn, C.; Liu, B.; Liu, G.; Lohn, S.; Longstaff, I.; Lopes, J. H.; Lopez-March, N.; Lu, H.; Lucchesi, D.; Luisier, J.; Luo, H.; Lupton, O.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Malde, S.; Manca, G.; Mancinelli, G.; Maratas, J.; Marconi, U.; Marino, P.; Märki, R.; Marks, J.; Martellotti, G.; Martens, A.; Martín Sánchez, A.; Martinelli, M.; Martinez Santos, D.; Martins Tostes, D.; Martynov, A.; Massafferri, A.; Matev, R.; Mathe, Z.; Matteuzzi, C.; Maurice, E.; Mazurov, A.; McCarthy, J.; McNab, A.; McNulty, R.; McSkelly, B.; Meadows, B.; Meier, F.; Meissner, M.; Merk, M.; Milanes, D. A.; Minard, M.-N.; Molina Rodriguez, J.; Monteil, S.; Moran, D.; Morawski, P.; Mordà, A.; Morello, M. J.; Mountain, R.; Mous, I.; Muheim, F.; Müller, K.; Muresan, R.; Muryn, B.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nasteva, I.; Needham, M.; Neubert, S.; Neufeld, N.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Nicol, M.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Nomerotski, A.; Novoselov, A.; Oblakowska-Mucha, A.; Obraztsov, V.; Oggero, S.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Orlandea, M.; Otalora Goicochea, J. M.; Owen, P.; Oyanguren, A.; Pal, B. K.; Palano, A.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Parkes, C.; Parkinson, C. J.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrick, G. N.; Patrignani, C.; Pavel-Nicorescu, C.; Pazos Alvarez, A.; Pearce, A.; Pellegrino, A.; Penso, G.; Pepe Altarelli, M.; Perazzini, S.; Perez Trigo, E.; Pérez-Calero Yzquierdo, A.; Perret, P.; Perrin-Terrin, M.; Pescatore, L.; Pesen, E.; Pessina, G.; Petridis, K.; Petrolini, A.; Phan, A.; Picatoste Olloqui, E.; Pietrzyk, B.; Pilař, T.; Pinci, D.; Playfer, S.; Plo Casasus, M.; Polci, F.; Polok, G.; Poluektov, A.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Powell, A.; Prisciandaro, J.; Pritchard, A.; Prouve, C.; Pugatch, V.; Puig Navarro, A.; Punzi, G.; Qian, W.; Rachwal, B.; Rademacker, J. H.; Rakotomiaramanana, B.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Redford, S.; Reichert, S.; Reid, M. M.; dos Reis, A. C.; Ricciardi, S.; Richards, A.; Rinnert, K.; Rives Molina, V.; Roa Romero, D. A.; Robbe, P.; Roberts, D. A.; Rodrigues, A. B.; Rodrigues, E.; Rodriguez Perez, P.; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Rotondo, M.; Rouvinet, J.; Ruf, T.; Ruffini, F.; Ruiz, H.; Ruiz Valls, P.; Sabatino, G.; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Salustino Guimaraes, V.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santovetti, E.; Sapunov, M.; Sarti, A.; Satriano, C.; Satta, A.; Savrie, M.; Savrina, D.; Schiller, M.; Schindler, H.; Schlupp, M.; Schmelling, M.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M.-H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Seco, M.; Semennikov, A.; Senderowska, K.; Sepp, I.; Serra, N.; Serrano, J.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, O.; Shevchenko, V.; Shires, A.; Silva Coutinho, R.; Sirendi, M.; Skidmore, N.; Skwarnicki, T.; Smith, N. A.; Smith, E.; Smith, E.; Smith, J.; Smith, M.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; Souza, D.; Souza De Paula, B.; Spaan, B.; Sparkes, A.; Spradlin, P.; Stagni, F.; Stahl, S.; Steinkamp, O.; Stevenson, S.; Stoica, S.; Stone, S.; Storaci, B.; Straticiuc, M.; Straumann, U.; Subbiah, V. K.; Sun, L.; Sutcliffe, W.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szczypka, P.; Szilard, D.; Szumlak, T.; T'Jampens, S.; Teklishyn, M.; Teodorescu, E.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M.; Tolk, S.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Tran, M. T.; Tresch, M.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Ubeda Garcia, M.; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vagnoni, V.; Valenti, G.; Vallier, A.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vázquez Sierra, C.; Vecchi, S.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vilasis-Cardona, X.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voß, C.; Voss, H.; Waldi, R.; Wallace, C.; Wallace, R.; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Webber, A. D.; Websdale, D.; Whitehead, M.; Wicht, J.; Wiechczynski, J.; Wiedner, D.; Wiggers, L.; Wilkinson, G.; Williams, M. P.; Williams, M.; Wilson, F. F.; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wright, S.; Wu, S.; Wyllie, K.; Xie, Y.; Xing, Z.; Yang, Z.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, F.; Zhang, L.; Zhang, W. C.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.; Zvyagin, A.
2013-12-01
A search for the doubly charmed baryon in the decay mode is performed with a data sample, corresponding to an integrated luminosity of 0.65 fb-1, of pp collisions recorded at a centre-of-mass energy of 7 TeV. No significant signal is found in the mass range 3300-3800 MeV /c 2. Upper limits at the 95% confidence level on the ratio of the production cross-section times branching fraction to that of the , R, are given as a function of the mass and lifetime. The largest upper limits range from R < 1.5 × 10-2 for a lifetime of 100 fs to R < 3 .9 × 10-4 for a lifetime of 400 fs. [Figure not available: see fulltext.
Brushless generation with cascaded doubly fed machines
NASA Astrophysics Data System (ADS)
Ortmeyer, T. H.; Borger, W. U.
The solid state converter used by the system operates at a fraction of the system power and frequency. What is more, the system operates without hydraulics. The fundamental characteristics of operation are discussed. Attention is given to the choice of optimum speeds and pole numbers for a given speed range. It is shown that two discrete operating modes exist for this type of system, namely subsynchronous and supersynchronous. System analysis is treated, and particular power, var, and frequency requirements for a 1.5:1 speed range system are presented. Cascaded doubly fed machines are seen as forming a viable basis for a generator system that holds considerable promise for operation that is high in reliability and low in cost.
Theoretical and experimental evidence of non-symmetric doubly localized rogue waves
He, Jingsong; Guo, Lijuan; Zhang, Yongshuai; Chabchoub, Amin
2014-01-01
We present determinant expressions for vector rogue wave (RW) solutions of the Manakov system, a two-component coupled nonlinear Schrödinger (NLS) equation. As a special case, we generate a family of exact and non-symmetric RW solutions of the NLS equation up to third order, localized in both space and time. The derived non-symmetric doubly localized second-order solution is generated experimentally in a water wave flume for deep-water conditions. Experimental results, confirming the characteristic non-symmetric pattern of the solution, are in very good agreement with theory as well as with numerical simulations, based on the modified NLS equation, known to model accurately the dynamics of weakly nonlinear wave packets in deep water. PMID:25383023
Doubly Magic Optical Trapping for Cs Atom Hyperfine Clock Transitions
NASA Astrophysics Data System (ADS)
Carr, A. W.; Saffman, M.
2016-10-01
We analyze doubly magic trapping of Cs hyperfine transitions including previously neglected contributions from the ground state hyperpolarizability and the interaction of the laser light and a static magnetic field. Extensive numerical searches do not reveal any doubly magic trapping conditions for any pair of hyperfine states. However, including the hyperpolarizability reveals light intensity insensitive traps for a wide range of wavelengths at specific intensities. We then investigate the use of bichromatic trapping light fields. Deploying a bichromatic scheme, we demonstrate doubly magic red and blue detuned traps for pairs of states separated by one or two single photon transitions.
Doubly stochastic Poisson processes in artificial neural learning.
Card, H C
1998-01-01
This paper investigates neuron activation statistics in artificial neural networks employing stochastic arithmetic. It is shown that a doubly stochastic Poisson process is an appropriate model for the signals in these circuits.
Doubly slanted layer structures in holographic gelatin emulsions: solar concentrators
NASA Astrophysics Data System (ADS)
Hung, Jenny; Chan, Po Shan; Sun, Caiming; Wing Ho, Choi; Tam, Wing Yim
2010-04-01
We have fabricated doubly slanted layer structures in holographic gelatin emulsions using a double-exposure two-beam interference from two light sources with different wavelengths. The doubly slanted layers, with different spacings and overlapping with each other, are fabricated such that they are slanted in opposite directions making a 30° angle with the holographic plate. The doubly slanted layer structures exhibit photonic stop bands corresponding to the two layered structures. More importantly, diffracted light beams from the slanted layers travel in different directions and emerge, through internal reflections, at the opposite edges of the gelatin plate. The doubly slanted layer structures could be used as solar concentrators such that sunlight is separated into different components and steered directly to photovoltaics with the corresponding wavelength sensitivities to enhance energy conversion efficiency.
Signatures of doubly-charged Higgsinos at colliders
Demir, D. A.; Frank, M.; Turan, I.; Huitu, K.; Rai, S. K.
2008-11-23
Several supersymmetric models with extended gauge structures predict light doubly-charged Higgsinos. Their distinctive signature at the large hadron collider is highlighted by studying its production and decay characteristics.
A simple formula for the energies of doubly excited states
Lin, C.D.; Watanabe, S.
1986-11-01
A simple formula for the energy levels of doubly excited states of atoms and multiply charged ions is derived and expressed in terms of a set of new correlation quantum numbers. The accuracy of the formula is checked by comparing with the results from other elaborate calculations. Modification of the formula for doubly excited states of multielectron atoms are also presented. 12 refs., 2 tabs.
Relating neutrino masses to dilepton modes of doubly charged scalars
Chen, Chian-Shu; Geng, C. Q.
2010-11-15
We study a model with Majorana neutrino masses generated through doubly charged scalars at two-loop level. We give explicit relationships between the neutrino masses and the same sign dilepton decays of the doubly charged scalars. In particular, we demonstrate that in the tribimaximal limit of the neutrino mixings, the absolute neutrino masses and Majorana phases can be extracted through the measurements of the dilepton modes at colliders.
Time reversal communication over doubly spread channels.
Zeng, Wen-Jun; Jiang, Xue
2012-11-01
Conventional time reversal can mitigate multipath delay dispersion by temporal focusing. But it is not applicable to time-varying channels with a Doppler spread. Although recently time reversal communication has been adapted to time-variant channels, the modified technique requires frequent channel updates to track channel variations and cannot handle large Doppler spread, which means that it cannot achieve frequency focusing. In this paper, two time reversal receivers for underwater acoustic communications over doubly spread channels are proposed. The proposed approach, which can be interpreted as time-frequency channel matching, is based on the channel spreading function rather than impulse response adopted by the existing techniques; this leads to much less frequent channel updates. Unlike existing methods that only correct a single Doppler shift, the proposed approach uses a rake-like structure to compensate for multiple Doppler shifts and hence can eliminate severe Doppler spread induced by temporal channel variations. Simulation results verify the effectiveness of the proposed approach, indicating that it can simultaneously counteract delay and Doppler spreads, achieving both temporal and frequency focusing.
Doubly stochastic coherence in complex neuronal networks
NASA Astrophysics Data System (ADS)
Gao, Yang; Wang, Jianjun
2012-11-01
A system composed of coupled FitzHugh-Nagumo neurons with various topological structures is investigated under the co-presence of two independently additive and multiplicative Gaussian white noises, in which particular attention is paid to the neuronal networks spiking regularity. As the additive noise intensity and the multiplicative noise intensity are simultaneously adjusted to optimal values, the temporal periodicity of the output of the system reaches the maximum, indicating the occurrence of doubly stochastic coherence. The network topology randomness exerts different influences on the temporal coherence of the spiking oscillation for dissimilar coupling strength regimes. At a small coupling strength, the spiking regularity shows nearly no difference in the regular, small-world, and completely random networks. At an intermediate coupling strength, the temporal periodicity in a small-world neuronal network can be improved slightly by adding a small fraction of long-range connections. At a large coupling strength, the dynamical behavior of the neurons completely loses the resonance property with regard to the additive noise intensity or the multiplicative noise intensity, and the spiking regularity decreases considerably with the increase of the network topology randomness. The network topology randomness plays more of a depressed role than a favorable role in improving the temporal coherence of the spiking oscillation in the neuronal network research study.
Razavi, Sonia M; Gonzalez, Marcial; Cuitiño, Alberto M
2015-04-30
We propose a general framework for determining optimal relationships for tensile strength of doubly convex tablets under diametrical compression. This approach is based on the observation that tensile strength is directly proportional to the breaking force and inversely proportional to a non-linear function of geometric parameters and materials properties. This generalization reduces to the analytical expression commonly used for flat faced tablets, i.e., Hertz solution, and to the empirical relationship currently used in the pharmaceutical industry for convex-faced tablets, i.e., Pitt's equation. Under proper parametrization, optimal tensile strength relationship can be determined from experimental results by minimizing a figure of merit of choice. This optimization is performed under the first-order approximation that a flat faced tablet and a doubly curved tablet have the same tensile strength if they have the same relative density and are made of the same powder, under equivalent manufacturing conditions. Furthermore, we provide a set of recommendations and best practices for assessing the performance of optimal tensile strength relationships in general. Based on these guidelines, we identify two new models, namely the general and mechanistic models, which are effective and predictive alternatives to the tensile strength relationship currently used in the pharmaceutical industry.
Nonlinear Mode-Coupling in Nanomechanical Systems
Matheny, M. H.; Villanueva, L. G.; Karabalin, R. B.; Sader, J. E.; Roukes, M. L.
2013-01-01
Understanding and controlling nonlinear coupling between vibrational modes is critical for the development of advanced nanomechanical devices; it has important implications for applications ranging from quantitative sensing to fundamental research. However, achieving accurate experimental characterization of nonlinearities in nanomechanical systems (NEMS) is problematic. Currently employed detection and actuation schemes themselves tend to be highly nonlinear, and this unrelated nonlinear response has been inadvertently convolved into many previous measurements. In this Letter we describe an experimental protocol and a highly linear transduction scheme, specifically designed for NEMS, that enables accurate, in situ characterization of device nonlinearities. By comparing predictions from Euler–Bernoulli theory for the intra- and intermodal nonlinearities of a doubly clamped beam, we assess the validity of our approach and find excellent agreement. PMID:23496001
Yaish, Y. E. Calahorra, Y.; Shtempluck, O.; Kotchetkov, V.
2015-04-28
A non-linear model is introduced describing the force-deflection relation of doubly clamped beams, including initial stress. Several approximations for the exact model are developed and compared, revealing the importance of considering the initial stress during 3-point bending measurements analysis. A novel approximation is found to be better than others, and both the exact model and this approximation are in perfect agreement with finite element simulations. A brief experimental example of silicon nanowires is presented in which the Young's modulus, the initial stress, and the crystallographic growth orientation are extracted by 3-point bending analysis.
Field evaporation of doubly charged ions from a polar liquid
NASA Astrophysics Data System (ADS)
Balakin, A. A.; Novikova, L. I.
2012-11-01
The effect of charge on field evaporation of ions from polar liquids is considered. Using the electromembrane ion source, we performed mass-spectral analysis of field evaporation of ions from the solution of sodium sulfate in a water-glycerol mixture. The composition of doubly charged cluster ions in the field evaporation from glycerol is determined. The rates of the field evaporation of doubly charged ions and singly charged ions are compared. It is shown that the ion charge as well as its localization considerably influences the efficiency of field evaporation of ions from polar liquids.
Measurement of Doubly Charged Ions in Ion Thruster Plumes
NASA Technical Reports Server (NTRS)
Williams, George J., Jr.; Domonkos, Matthew T.; Chavez, Joy M.
2002-01-01
The ratio of doubly to singly charged ions was measured in the plumes of a 30 cm and of a 40 cm ion thruster. The measured ratio was correlated with observed erosion rates and thruster operating conditions. The measured and calculated erosion rates paralleled variation in the j(sup ++)/j(sup +) ratio and indicated that the erosion was dominated by Xe III. Simple models of cathode potential surfaces which were developed in support of this work were in agreement with this conclusion and provided a predictive capability of the erosion given the ratio of doubly to singly charged ion currents.
Search for doubly charged Higgs bosons at LEP2
NASA Astrophysics Data System (ADS)
Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alderweireld, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Bugge, L.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crawley, B.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Dris, M.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Geralis, T.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Hansen, J.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Hultqvist, K.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kiiskinen, A.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Meyer, W. T.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Ramler, L.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Rosenberg, E.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Savoy-Navarro, A.; Schwickerath, U.; Segar, A.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tomaradze, A.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Lysebetten, A.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verbeure, F.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zimin, N. I.; Zintchenko, A.; Zupan, M.; Delphi Collaboration
2003-01-01
A search for pair-produced doubly charged Higgs bosons has been performed using the data collected by the DELPHI detector at LEP at centre-of-mass energies between 189 and 209 GeV. No excess is observed in the data with respect to the Standard Model background. A lower limit for the mass of 97.3 GeV/c2 at the 95% confidence level has been set for doubly charged Higgs bosons in left-right symmetric models for any value of the Yukawa coupling between the Higgs bosons and the τ leptons.
Search for doubly charged Higgs bosons at LEP2
NASA Astrophysics Data System (ADS)
DELPHI Collaboration; Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alderweireld, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Bugge, L.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crawley, B.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Dris, M.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Geralis, T.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Hansen, J.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Hultqvist, K.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kiiskinen, A.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Meyer, W. T.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Ramler, L.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Rosenberg, E.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Savoy-Navarro, A.; Schwickerath, U.; Segar, A.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tomaradze, A.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Lysebetten, A.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verbeure, F.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zimin, N. I.; Zintchenko, A.; Zupan, M.
2003-01-01
A search for pair-produced doubly charged Higgs bosons has been performed using the data collected by the DELPHI detector at LEP at centre-of-mass energies between 189 and 209 GeV. No excess is observed in the data with respect to the Standard Model background. A lower limit for the mass of 97.3 GeV/c2 at the 95% confidence level has been set for doubly charged Higgs bosons in left-right symmetric models for any value of the Yukawa coupling between the Higgs bosons and the /τ leptons.
A mathematical model for the doubly fed wound rotor generator
NASA Technical Reports Server (NTRS)
Brady, F. J.
1983-01-01
A mathematical analysis of a doubly-fed wound rotor machine used as a constant frequency generator is presented. The purpose of this analysis is to derive a consistent set of circuit equations which produce constant stator frequency and constant stator voltage. Starting with instantaneous circuit equations, the necessary rotor voltages and currents are derived. The model, thus obtained, is assumed to be valid, since the resulting relationships between mechanical power and active volt-amperes agrees with the results of others. In addition, the model allows for a new interpretation of the power flow in the doubly-fed generator.
NASA Astrophysics Data System (ADS)
Chinone, N.; Nakamura, T.; Cho, Y.
2014-08-01
The dopant distribution and depletion layer in a cross-section of a SiC double diffused MOSFET (DMOSFET) is visualized using super-higher-order scanning nonlinear dielectric microscopy (SHO-SNDM), which is a form of scanning probe microscopy. Analysis of the data acquired by SHO-SNDM clarifies the dopant distribution in great detail, which is otherwise difficult to detect using conventional scanning capacitance microscopy or scanning microwave microscopy. Moreover, the newly developed SHO-SNDM method enables us to distinguish the n-type, p-type, and depletion layer regions very clearly, and they are found to be consistent with the general DMOSFET structure.
Band structure of doubly-odd nuclei around mass 130
Higashiyama, Koji; Yoshinaga, Naotaka
2011-05-06
Nuclear structure of the doublet bands in the doubly-odd nuclei with mass A{approx}130 is studied in terms of a pair-truncated shell model. The model reproduces quite well the energy levels of the doublet bands and the electromagnetic transitions. The analysis of the electromagnetic transitions reveals new band structure of the doublet bands.
Doubly Lopsided Models From SUSY SU(N)
Barr, S. M.
2008-11-23
It is shown that the doubly lopsided mass matrices, which are known to give realistic patterns of quark and lepton masses and mixings, arise naturally in the context of supersymmetric grand unified models based on SU(N) with N>5. An SU(7) model is presented as an illustration.
Ebrahimkhani, Sadegh
2016-07-01
Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme.
NASA Astrophysics Data System (ADS)
McLaughlin, David W.
1994-01-01
The principal investigator, together with two post-doctoral fellows, several graduate students, and colleagues, has applied the modern mathematical theory of nonlinear waves to problems in nonlinear optics. Projects included the interaction of laser light with nematic liquid crystals, propagation through random nonlinear media, cross polarization instabilities and optical shocks for propagation along nonlinear optical fibers, and the dynamics of bistable optical switches coupled through both diffusion and diffraction. In the first project the extremely strong nonlinear response of a CW laser beam in a nematic liquid crystal medium produced striking undulation and filamentation of the CW beam which was observed experimentally and explained theoretically. In the second project the interaction of randomness with nonlinearity was investigated, as well as an effective randomness due to the simultaneous presence of many nonlinear instabilities. In the polarization problems theoretical hyperbolic structure (instabilities and homoclinic orbits) in the coupled nonlinear Schroedinger (NLS) equations was identified and used to explain cross polarization instabilities in both the focusing and defocusing cases, as well as to describe optical shocking phenomena. For the coupled bistable optical switches, a numerical code was carefully developed in two spatial and one temporal dimensions. The code was used to study the decay of temporal transients to 'on-off' steady states in a geometry which includes forward and backward longitudinal propagation, together with one dimensional transverse coupling of both electromagnetic diffraction and carrier diffusion.
Wu, Yu-Chien; Alexander, Andrew L.
2007-01-01
Diffusion measurements in the human central nervous system are complex to characterize and a broad spectrum of methods have been proposed. In this study, a comprehensive diffusion encoding and analysis approach, Hybrid Diffusion Imaging (HYDI), is described. The HYDI encoding scheme is composed of multiple concentric “shells” of constant diffusion-weighting, which may be used to characterize the signal behavior with low, moderate and high diffusion-weighting. HYDI facilitates the application of multiple data-analyses strategies including diffusion tensor imaging (DTI), multi-exponential diffusion measurements, diffusion spectrum imaging (DSI) and q-ball imaging (QBI). These different analysis strategies may provide complementary information. DTI measures (mean diffusivity and fractional anisotropy) may be estimated from either data in the inner shells or the entire HYDI data. Fast and slow diffusivities were estimated using a nonlinear least-squares bi-exponential fit on geometric means of the HYDI shells. DSI measurements from the entire HYDI data yield empirical model-independent diffusion information and are well-suited for characterizing tissue regions with complex diffusion behavior. DSI measurements were characterized using the zero displacement probability and the mean squared displacement. The outermost HYDI shell was analyzed using QBI analysis to estimate the orientation distribution function (ODF), which is useful for characterizing the directions of multiple fiber groups within a voxel. In this study, a HYDI encoding scheme with 102 diffusion-weighted measurements was obtained over most of the human cerebrum in under 30 minutes. PMID:17481920
Doubly-charged ions in the planetary ionospheres: a review.
Thissen, Roland; Witasse, Olivier; Dutuit, Odile; Wedlund, Cyril Simon; Gronoff, Guillaume; Lilensten, Jean
2011-11-01
This paper presents a review of the current knowledge on the doubly-charged atomic and molecular positive ions in the planetary atmospheres of the Solar System. It is focused on the terrestrial planets which have a dense atmosphere of N(2) or CO(2), i.e. Venus, the Earth and Mars, but also includes Titan, the largest satellite of Saturn, which has a dense atmosphere composed mainly of N(2) and a few percent of methane. Given the composition of these neutral atmospheres, the following species are considered: C(++), N(++), O(++), CH(4)(++), CO(++), N(2)(++), NO(++), O(2)(++), Ar(++) and CO(2)(++). We first discuss the status of their detection in the atmospheres of planets. Then, we provide a comprehensive review of their complex and original photochemistry, production and loss processes. Synthesis tables are provided for those ions, while a discussion on individual species is also provided. Methods for detecting doubly-charged ions in planetary atmospheres are presented, namely with mass-spectrometry, remote sensing and fine plasma density measurements. A section covers some original applications, like the possible effect of the presence of doubly-charged ions on the escape of an atmosphere, which is a key topic of ongoing planetary exploration, related to the evolution of a planet. The results of models, displayed in a comparative way for Venus, Earth, Mars and Titan, are discussed, as they can predict the presence of doubly-charged ions and will certainly trigger new investigations. Finally we give our view concerning next steps, challenges and needs for future studies, hoping that new scientific results will be achieved in the coming years and feed the necessary interdisciplinary exchanges amongst different scientific communities. PMID:21931881
Influence of curvature on the losses of doubly clad fibers.
Marcuse, D
1982-12-01
The loss increase of the HE(11) mode of a doubly clad (depressed-index) fiber due to constant curvature is considered. The calculations presented in this paper are based on a simplified theory. We find that for typical fibers the leakage loss of the HE(11) mode begins to increase significantly when the radius of curvature of the fiber axis reaches the 1-10-cm range.
Alternating parity structure in doubly odd /sup 218/Ac
Debray, M.E.; Davidson, M.; Kreiner, A.J.; Davidson, J.; Falcone, G.; Hojman, D.; Santos, D.
1989-03-01
States in doubly odd /sup 218/Ac have been studied using in-beam ..cap alpha..-, ..gamma..-, and e/sup -/-spectroscopy techniques mainly through the /sup 209/Bi(/sup 12/C,3n)= fusion-evaporation reaction. /sup 218/Ac shows a band structure, with interleaved states of alternating parities connected by enhanced B(E1) transitions, which is strikingly similar to the one in its isotone /sup 217/Ra.
Doubly Excited Resonances in the Positronium Negative Ion
NASA Technical Reports Server (NTRS)
Ho, Y.K.
2007-01-01
The recent theoretical studies on the doubly excited states of the Ps' ion are described. The results obtained by using the method of complex coordinate rotation show that the three-lepton system behaves very much like an XYX tri-atomic molecule. Furthermore, the recent investigation on the positronium negative ion embedded in Debye plasma environments is discussed. The problem is modeled by the use of a screened Coulomb potential to represent the interaction between the charge particles.
Doubly Excited Resonance States of Helium Atom: Complex Entropies
NASA Astrophysics Data System (ADS)
Kuroś, Arkadiusz; Kościk, Przemysław; Saha, Jayanta K.
2016-09-01
We provide a diagonal form of a reduced density matrix of S-symmetry resonance states of two electron systems determined under the framework of the complex scaling method. We have employed the variational Hylleraas type wavefunction to estimate the complex entropies in doubly excited resonance states of helium atom. Our results are in good agreement with the corresponding ones determined under the framework of the stabilization method (Lin and Ho in Few-Body Syst 56:157, 2015).
Doubly curved nanofiber-reinforced optically transparent composites
Shams, Md. Iftekhar; Yano, Hiroyuki
2015-01-01
Doubly curved nanofiber-reinforced optically transparent composites with low thermal expansion of 15 ppm/k are prepared by hot pressing vacuum-filtered Pickering emulsions of hydrophobic acrylic resin monomer, hydrophilic chitin nanofibers and water. The coalescence of acrylic monomer droplets in the emulsion is prevented by the chitin nanofibers network. This transparent composite has 3D shape moldability, making it attractive for optical precision parts. PMID:26552990
Doubly curved nanofiber-reinforced optically transparent composites
NASA Astrophysics Data System (ADS)
Shams, Md. Iftekhar; Yano, Hiroyuki
2015-11-01
Doubly curved nanofiber-reinforced optically transparent composites with low thermal expansion of 15 ppm/k are prepared by hot pressing vacuum-filtered Pickering emulsions of hydrophobic acrylic resin monomer, hydrophilic chitin nanofibers and water. The coalescence of acrylic monomer droplets in the emulsion is prevented by the chitin nanofibers network. This transparent composite has 3D shape moldability, making it attractive for optical precision parts.
Doubly heavy baryon spectra guided by lattice QCD
NASA Astrophysics Data System (ADS)
Garcilazo, H.; Valcarce, A.; Vijande, J.
2016-10-01
This paper provides results for the ground state and excited spectra of three-flavored doubly heavy baryons, b c n and b c s . We take advantage of the spin-independent interaction recently obtained to reconcile the lattice SU(3) QCD static potential and the results of nonperturbative lattice QCD for the triply heavy baryon spectra. We show that the spin-dependent potential might be constrained on the basis of nonperturbative lattice QCD results for the spin splittings of three-flavored doubly heavy baryons. Our results may also represent a challenge for future lattice QCD work, because a smaller lattice error could help in distinguishing between different prescriptions for the spin-dependent part of the interaction. Thus, by comparing with the reported baryon spectra obtained with parameters estimated from lattice QCD, one can challenge the precision of lattice calculations. The present work supports a coherent description of singly, doubly and triply heavy baryons with the same Cornell-like interacting potential. The possible experimental measurement of these states at LHCb is an incentive for this study.
Doubly sensitivity-enhanced 3D TOCSY-HSQC.
Wijmenga, S S; van Mierlo, C P; Steensma, E
1996-10-01
Recently, strategies for double sensitivity enhancement in heteronuclear three-dimensional NMR experiments were introduced (Krishnamurthy, V.V. (1995) J. Magn. Reson., B106, 170-177; Sattler et al. (1995) J. Biomol. NMR, 6, 11-22; Sattler et al. (1995) J. Magn. Reson., B108, 235-242). Since a sensitivity enhancement of a factor 2(1/2) can be achieved for each indirect dimension, nD spectra can theoretically be enhanced up to a factor of 2(((n-1)/2)). We propose and analyze a doubly enhanced three-dimensional TOCSY-HSQC sequence. The application of the doubly enhanced three-dimensional {(15)N, (1)H} TOCSY-HSQC sequence is shown for uniformly (13)C-/(15)N- and (15)N-labeled samples of the relatively large Azotobacter vinelandii flavodoxin II (179 amino acids). The main factors that contribute to the final signal-to-noise enhancement have been systematically investigated. The sensitivity enhancement obtained for the doubly enhanced TOCSY-HSQC pulse sequence as compared to the standard (unenhanced) version is close to the theoretically expected factor of two.
Nonlinear ultrasonic phased array imaging.
Potter, J N; Croxford, A J; Wilcox, P D
2014-10-01
This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.
NASA Technical Reports Server (NTRS)
Ko, William L.; Richards, W. Lance; Fleischer, Van Tran
2009-01-01
The Ko displacement theory, formulated for weak nonuniform (slowly changing cross sections) cantilever beams, was applied to the deformed shape analysis of the doubly-tapered wings of the Ikhana unmanned aircraft. The two-line strain-sensing system (along the wingspan) was used for sensing the bending strains needed for the wing-deformed shapes (deflections and cross-sectional twist) analysis. The deflection equation for each strain-sensing line was expressed in terms of the bending strains evaluated at multiple numbers of strain-sensing stations equally spaced along the strain-sensing line. For the preflight shape analysis of the Ikhana wing, the strain data needed for input to the displacement equations for the shape analysis were obtained from the nodal-stress output of the finite-element analysis. The wing deflections and cross-sectional twist angles calculated from the displacement equations were then compared with those computed from the finite-element computer program. The Ko displacement theory formulated for weak nonlinear cantilever beams was found to be highly accurate in the deformed shape predictions of the doubly-tapered Ikhana wing.
Center mode of a doubly resonant optical periodic structure
NASA Astrophysics Data System (ADS)
Alagappan, G.; Png, C. E.
2016-07-01
An optical periodic structure with a single spatial resonance exhibits a stopband. When a second spatial resonance very close to the first one is added, the resulting doubly resonant structure exhibits a Gaussian enveloped, high quality factor transmission state right at the center of the original stopband. Using a slowly varying envelope approximation, we describe the optical characteristics of this transmission state analytically. The transmission state exists despite an optical structure of low refractive index contrast, and has potential applications in nano-optics, and photonics.
Numerical conformal mapping methods for exterior and doubly connected regions
DeLillo, T.K.; Pfaltzgraff, J.A.
1996-12-31
Methods are presented and analyzed for approximating the conformal map from the exterior of the disk to the exterior a smooth, simple closed curve and from an annulus to a bounded, doubly connected region with smooth boundaries. The methods are Newton-like methods for computing the boundary correspondences and conformal moduli similar to Fornberg`s method for the interior of the disk. We show that the linear systems are discretizations of the identity plus a compact operator and, hence, that the conjugate gradient method converges superlinearly.
Resonant meta-atoms with nonlinearities on demand
NASA Astrophysics Data System (ADS)
Filonov, Dmitry; Kramer, Yotam; Kozlov, Vitali; Malomed, Boris A.; Ginzburg, Pavel
2016-09-01
Nonlinear light-matter interactions and their applications are constrained by properties of available materials. The use of metamaterials opens the way to achieve precise control over electromagnetic properties at a microscopic level, providing tools for experimental studies of complex nonlinear phenomena in photonics. Here, a doubly resonant nonlinear meta-atom is proposed, analyzed, and characterized in the GHz spectral range. The underlying structure is composed of a pair of split rings, resonant at both fundamental and nonlinear frequencies. The rings share a varactor diode, which serves as a microscopic source of nonlinearity. Flexible control over the coupling and near- and far-field patterns are reported, favoring the doubly resonant structure over other realizations. Relative efficiencies of the second and third harmonics, generated by the diode, are tailored by dint of the double-ring geometry, providing a guideline for selecting one frequency against another, using the design of the auxiliary structures. The on-demand control over the microscopic nonlinear properties enables developing a toolbox for experimental emulation of complex nonlinear phenomena.
Young's Modulus, Residual Stress, and Crystal Orientation of Doubly Clamped Silicon Nanowire Beams.
Calahorra, Y; Shtempluck, O; Kotchetkov, V; Yaish, Y E
2015-05-13
Initial or residual stress plays an important role in nanoelectronics. Valley degeneracy in silicon nanowires (SiNWs) is partially lifted due to built-in stresses, and consequently, electron-phonon scattering rate is reduced and device mobility and performance are improved. In this study we use a nonlinear model describing the force-deflection relationship to extract the Young's modulus, the residual stress, and the crystallographic growth orientation of SiNW beams. Measurements were performed on suspended doubly clamped SiNWs subjected to atomic force microscopy (AFM) three-point bending constraints. The nanowires comprised different growth directions and two SiO2 sheath thicknesses, and underwent different rapid thermal annealing processes. Analysis showed that rapid thermal annealing introduces compressive strains into the SiNWs and may result in buckling of the SiNWs. Furthermore, the core-shell model together with the residual stress analysis accurately describe the Young's modulus of oxide covered SiNWs and the crystal orientation of the measured nanowires. PMID:25826449
Study of a control strategy for grid side converter in doubly- fed wind power system
NASA Astrophysics Data System (ADS)
Zhu, D. J.; Tan, Z. L.; Yuan, F.; Wang, Q. Y.; Ding, M.
2016-08-01
The grid side converter is an important part of the excitation system of doubly-fed asynchronous generator used in wind power system. As a three-phase voltage source PWM converter, it can not only transfer slip power in the form of active power, but also adjust the reactive power of the grid. This paper proposed a control approach for improving its performance. In this control approach, the dc voltage is regulated by a sliding mode variable structure control scheme and current by a variable structure controller based on the input output linearization. The theoretical bases of the sliding mode variable structure control were introduced, and the stability proof was presented. Switching function of the system has been deduced, sliding mode voltage controller model has been established, and the output of the outer voltage loop is the instruction of the inner current loop. Affine nonlinear model of two input two output equations on d-q axis for current has been established its meeting conditions of exact linearization were proved. In order to improve the anti-jamming capability of the system, a variable structure control was added in the current controller, the control law was deduced. The dual-loop control with sliding mode control in outer voltage loop and linearization variable structure control in inner current loop was proposed. Simulation results demonstrate the effectiveness of the proposed control strategy even during the dc reference voltage and system load variation.
Young's Modulus, Residual Stress, and Crystal Orientation of Doubly Clamped Silicon Nanowire Beams.
Calahorra, Y; Shtempluck, O; Kotchetkov, V; Yaish, Y E
2015-05-13
Initial or residual stress plays an important role in nanoelectronics. Valley degeneracy in silicon nanowires (SiNWs) is partially lifted due to built-in stresses, and consequently, electron-phonon scattering rate is reduced and device mobility and performance are improved. In this study we use a nonlinear model describing the force-deflection relationship to extract the Young's modulus, the residual stress, and the crystallographic growth orientation of SiNW beams. Measurements were performed on suspended doubly clamped SiNWs subjected to atomic force microscopy (AFM) three-point bending constraints. The nanowires comprised different growth directions and two SiO2 sheath thicknesses, and underwent different rapid thermal annealing processes. Analysis showed that rapid thermal annealing introduces compressive strains into the SiNWs and may result in buckling of the SiNWs. Furthermore, the core-shell model together with the residual stress analysis accurately describe the Young's modulus of oxide covered SiNWs and the crystal orientation of the measured nanowires.
Spectroscopy of doubly charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2015-05-06
This study presents the ground and excited state spectra of doubly charmed baryons from lattice QCD with dynamical quark fields. Calculations are performed on anisotropic lattices of size 16³ × 128, with inverse spacing in temporal direction a_{t}⁻¹=5.67(4) GeV and with a pion mass of about 390 MeV. A large set of baryonic operators that respect the symmetries of the lattice yet which retain a memory of their continuum analogues are used. These operators transform as irreducible representations of SU(3)_{F} symmetry for flavor, SU(4) symmetry for Dirac spins of quarks and O(3) for spatial symmetry. The distillation method is utilized to generate baryon correlation functions which are analyzed using the variational fitting method to extract excited states. The lattice spectra obtained have baryonic states with well-defined total spins up to 7/2 and the pattern of low-lying states does not support the diquark picture for doubly charmed baryons. On the contrary the calculated spectra are remarkably similar to the expectations from models with an SU(6)×O(3) symmetry. Various spin-dependent energy splittings between the extracted states are also evaluated.
Lensless coded aperture imaging with separable doubly Toeplitz masks
NASA Astrophysics Data System (ADS)
DeWeert, Michael J.; Farm, Brian P.
2014-05-01
In certain imaging applications, conventional lens technology is constrained by the lack of materials which can effectively focus the radiation within reasonable weight and volume. One solution is to use coded apertures -opaque plates perforated with multiple pinhole-like openings. If the openings are arranged in an appropriate pattern, the images can be decoded, and a clear image computed. Recently, computational imaging and the search for means of producing programmable software-defined optics have revived interest in coded apertures. The former state-of-the-art masks, MURAs (Modified Uniformly Redundant Arrays) are effective for compact objects against uniform backgrounds, but have substantial drawbacks for extended scenes: 1) MURAs present an inherently ill-posed inversion problem that is unmanageable for large images, and 2) they are susceptible to diffraction: a diffracted MURA is no longer a MURA. This paper presents a new class of coded apertures, Separable Doubly-Toeplitz masks, which are efficiently decodable, even for very large images -orders of magnitude faster than MURAs, and which remain decodable when diffracted. We implemented the masks using programmable spatial-lightmodulators. Imaging experiments confirmed the effectiveness of Separable Doubly-Toeplitz masks - images collected in natural light of extended outdoor scenes are rendered clearly.
Validation of doubly labeled water method using a ruminant
Fancy, S.G.; Blanchard, J.M.; Holleman, D.F.; Kokjer, K.J.; White, R.G.
1986-07-01
CO/sub 2/ production (CDP, ml CO/sub 2/ . g-1 . h-1) by captive caribou and reindeer (Rangifer tarandus) was measured using the doubly labeled water method (/sup 3/H/sub 2/O and H2(18)O) and compared with CO/sub 2/ expiration rates (VCO/sub 2/), adjusted for CO/sub 2/ losses in CH4 and urine, as determined by open-circuit respirometry. CDP calculated from samples of blood or urine from a reindeer in winter was 1-3% higher than the adjusted VCO/sub 2/. Differences between values derived by the two methods of 5-20% were found in summer trials with caribou. None of these differences were statistically significant (P greater than 0.05). Differences in summer could in part be explained by the net deposition of /sup 3/H, 18O, and unlabeled CO/sub 2/ in antlers and other growing tissues. Total body water volumes calculated from /sup 3/H/sub 2/O dilution were up to 15% higher than those calculated from H/sub 2/(18)O dilution. The doubly labeled water method appears to be a reasonably accurate method for measuring CDP by caribou and reindeer in winter when growth rates are low, but the method may overestimate CDP by rapidly growing and/or fattening animals.
NASA Astrophysics Data System (ADS)
Anwar Bég, O.; Zueco, J.; Takhar, H. S.; Bég, T. A.; Sajid, A.
2009-11-01
A boundary-layer model is described for the two-dimensional nonlinear transient thermal convection heat and mass transfer in an optically-thick fluid in a Darcian porous medium adjacent to an impulsively started vertical surface, in the presence of significant thermal radiation and buoyancy forces in an (X∗,Y∗,t∗) coordinate system. An algebraic approximation is employed to simplify the integro-differential equation of radiative transfer for unidirectional flux normal to the plate into the boundary-layer regime, by incorporating this flux term in the energy conservation equation. The conservation equations are non-dimensionalized into an (X,Y,T) coordinate system and solved using the Network Simulation Method (NSM), a robust numerical technique which demonstrates high efficiency and accuracy. The transient variation of non-dimensional streamwise velocity component (u) and temperature (T) and concentration (C) functions is computed for various selected values of Stark number (radiation-conduction interaction parameter) and Darcy number. Transient velocity (u) and steady-state local skin friction (τX) are also studied for various thermal Grashof number (Gr), species Grashof number (Gm), Schmidt number (Sc) and Stark number (N) values. These computations for the infinite permeability case (Da → ∞) are compared with previous finite difference solutions [Prasad et al. Int J Therm Sci 2007;46(12):1251-8] and shown to be in excellent agreement. An increase in Darcy number is seen to accelerate the flow and boost velocity. A decrease in Stark number (corresponding to an increase in thermal radiation heat transfer contribution) is shown to increase the velocity values. Temperature function is observed to fall in value with a rise in Da and increase with decrease in N (corresponding to an increase in thermal radiation heat transfer contribution). Applications of the study include rocket combustion chambers, astrophysical flows, spacecraft thermal fluid dynamics in
Cosmic ray diffusion: Report of the Workshop in Cosmic Ray Diffusion Theory
NASA Technical Reports Server (NTRS)
Birmingham, T. J.; Jones, F. C.
1975-01-01
A workshop in cosmic ray diffusion theory was held at Goddard Space Flight Center on May 16-17, 1974. Topics discussed and summarized are: (1) cosmic ray measurements as related to diffusion theory; (2) quasi-linear theory, nonlinear theory, and computer simulation of cosmic ray pitch-angle diffusion; and (3) magnetic field fluctuation measurements as related to diffusion theory.
Observation of the doubly strange b baryon Omegab-.
Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Andrieu, B; Anzelc, M S; Aoki, M; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Avila, C; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Bu, X B; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Carrera, E; Carvalho, W; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cuplov, V; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; DeVaughan, K; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dorland, T; Dubey, A; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Geng, W; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Johnston, D; Jonckheere, A; Jonsson, P; Juste, A; Kajfasz, E; Kalk, J M; Karmanov, D; Kasper, P A; Katsanos, I; Kau, D; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Komissarov, E V; Konrath, J-P; Kozelov, A V; Kraus, J; Kuhl, T; Kumar, A; Kupco, A; Kurca, T; Kuzmin, V A; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lebrun, P; Lee, W M; Leflat, A; Lellouch, J; Li, J; Li, L; Li, Q Z; Lietti, S M; Lim, J K; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna, R; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendoza, L; Mercadante, P G; Merekov, Y P; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Mitrevski, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nogima, H; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Orduna, J; Oshima, N; Osman, N; Osta, J; Otec, R; Otero y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perfilov, M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Polozov, P; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Ranjan, K; Ratoff, P N; Renkel, P; Rich, P; Rieger, J; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Rominsky, M; Royon, C; Rozhdestvenski, A; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Sanghi, B; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schlobohm, S; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, E; Strauss, M; Ströhmer, R; Strom, D; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Tamburello, P; Tanasijczuk, A; Taylor, W; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Torchiani, I; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; van den Berg, P J; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Verdier, P; Vertogradov, L S; Vertogradova, Y; Verzocchi, M; Vilanova, D; Villeneuve-Seguier, F; Vint, P; Vokac, P; Voutilainen, M; Wagner, R; Wahl, H D; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Welty-Rieger, L; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Williams, M; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yang, W-C; Yasuda, T; Yatsunenko, Y A; Yin, H; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zeitnitz, C; Zelitch, S; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G
2008-12-01
We report the observation of the doubly strange b baryon Omegab- in the decay channel Omegab(-)-->J/psiOmega-, with J/psi-->mu+mu(-) and Omega(-)-->LambdaK(-)-->(ppi-)K-, in pp collisions at sqrt[s]=1.96 TeV. Using approximately 1.3 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17.8+/-4.9(stat)+/-0.8(syst) Omegab- signal events at a mass of 6.165+/-0.010(stat)+/-0.013(syst) GeV. The significance of the observed signal is 5.4sigma, corresponding to a probability of 6.7 x 10(-8) of it arising from a background fluctuation. PMID:19113541
Near yrast states in doubly odd [sup 214]Fr
Debray, M.E.; Kreiner, A.J.; Kesque, J.M.; Ozafran, M.; Romo, A.; Somacal, H.; Vazquez, M.E. ); Davidson, J.; Davidson, M. ); Ahn, K.; Fossan, D.B.; Liang, Y.; Ma, R.; Paul, E.S.; Piel, W.F. Jr.; Xu, N. )
1993-11-01
High spin states of doubly odd [sup 214]Fr[sub 127] have been investigated using in-beam [gamma]-ray and conversion electron spectroscopy techniques through the [sup 206]Pb([sup 11]B, 3[ital n]) and [sup 208]Pb([sup 11]B, 5[ital n]) fusion-evaporation reactions. Completely new spectrocopic information has been obtained. The yrast level structure is established up to spin (19[sup +]) and some information on [gamma] transitions from higher-lying levels is also obtained. Two new isomers [ital T][sub 1/2]=174(20) ns and [ital T][sub 1/2]=11(2) ns were found. Configuration assignments for the low-lying levels are discussed. Information on residual proton-neutron interactions is extracted.
Triple differential cross sections of magnesium in doubly symmetric geometry
NASA Astrophysics Data System (ADS)
S, Y. Sun; X, Y. Miao; Xiang-Fu, Jia
2016-01-01
A dynamically screened three-Coulomb-wave (DS3C) method is applied to study the single ionization of magnesium by electron impact. Triple differential cross sections (TDCS) are calculated in doubly symmetric geometry at incident energies of 13.65, 17.65, 22.65, 27.65, 37.65, 47.65, 57.65, and 67.65 eV. Comparisons are made with experimental data and theoretical predictions from a three-Coulomb-wave function (3C) approach and distorted-wave Born approximation (DWBA). The overall agreement between the predictions of the DS3C model and the DWBA approach with the experimental data is satisfactory. Project supported by the National Natural Science Foundation of China (Grant No. 11274215).
Respiratory compensation in cardiac PET using doubly-gated acquisitions
Huesman, R.H.; Klein, G.J.; Reutter, B.W.
1997-05-01
We present results of respiratory compensation in cardiac PET data via doubly-gated acquisitions on a human subject. The extent of cardiac motion due to respiration has now been documented by numerous researchers. To correct for the blurring effects of this motion, we have modified the CTI/Siemens ECAT EXACT HR scanner to support acquisitions gated for different stages of both the cardiac and respiratory cycles. A human subject was injected with 11.0 mCi 18-FDG. After allowing time for the isotope to clear the blood pool, emission data were acquired for 30 minutes. The respiratory cycle was divided into five gates, the cardiac cycle into three gates for a total of fifteen 47-plane emission datasets. An ungated transmission dataset was acquired to correct for the effects of attenuation. Each gate was separately reconstructed using standard filtered backprojection techniques. Data resulting from the five respiratory gates obtained during diastole will be discussed in this paper.
Doubly infinite separation of quantum information and communication
NASA Astrophysics Data System (ADS)
Liu, Zi-Wen; Perry, Christopher; Zhu, Yechao; Koh, Dax Enshan; Aaronson, Scott
2016-01-01
We prove the existence of (one-way) communication tasks with a subconstant versus superconstant asymptotic gap, which we call "doubly infinite," between their quantum information and communication complexities. We do so by studying the exclusion game [C. Perry et al., Phys. Rev. Lett. 115, 030504 (2015), 10.1103/PhysRevLett.115.030504] for which there exist instances where the quantum information complexity tends to zero as the size of the input n increases. By showing that the quantum communication complexity of these games scales at least logarithmically in n , we obtain our result. We further show that the established lower bounds and gaps still hold even if we allow a small probability of error. However in this case, the n -qubit quantum message of the zero-error strategy can be compressed polynomially.
Doubly Cavitand-Capped Porphyrin Capsule by Hydrogen Bonds.
Kishimoto, Kazuki; Nakamura, Munechika; Kobayashi, Kenji
2016-02-18
The components of a 1:2 mixture of meso-tetrakis(4-dodecyl-3,5-dihydroxyphenyl)porphyrin (1) and a bowl-shaped tetrakis(4-pyridylethynyl)cavitand (2) in CDCl3 or C6 D6 self-assemble quantitatively into the doubly cavitand-capped porphyrin capsule 2⋅1⋅2 through eight ArOH⋅⋅⋅Npy hydrogen bonds. Capsule 2⋅1⋅2 possesses two cavities divided by the porphyrin ring and encapsulates two molecules of 1-acetoxy-3,5-dimethoxybenzene (G) as a guest to form G/G@(2⋅1⋅2). Remarkable solvent effect was observed, in which the apparent association constant of 2⋅1⋅2 with G in C6 D6 was much greater than that in CDCl3. PMID:26728330
Doubly ordered superconducting state in a doped antiferromagnet
Belyavskii, V. I. Kopaev, Yu. V.; Tuan, Nguyen Ngoc
2007-10-15
In a weakly doped quasi-two-dimensional antiferromagnet with a Fermi contour in the form of small pockets, the Coulomb repulsion gives rise to a doubly ordered superconducting state of coexisting condensates with a large pair momentum and a zero one. The pairing with the large momentum determines the superconducting transition temperature, below which the order with zero momentum coexists as an induced order until the temperature corresponding to the initiation of the phonon pairing mechanism is reached. The superconductivity-induced orbital current density wave eliminates the pairing-repulsion-caused zero points from the two-gap quasiparticle spectrum and leads to a deviation of the relative phase of the superconducting order parameter components from {pi}.
Properties of Doubly Heavy Baryons in the Relativistic Quark Model
Ebert, D.; Faustov, R.N.; Galkin, V.O.; Martynenko, A.P.
2005-05-01
Mass spectra and semileptonic decay rates of baryons consisting of two heavy (b or c) and one light quark are calculated in the framework of the relativistic quark model. The doubly heavy baryons are treated in the quark-diquark approximation. The ground and excited states of both the diquark and quark-diquark bound systems are considered. The quark-diquark potential is constructed. The light quark is treated completely relativistically, while the expansion in the inverse heavy-quark mass is used. The weak transition amplitudes of heavy diquarks bb and bc going, respectively, to bc and cc are explicitly expressed through the overlap integrals of the diquark wave functions in the whole accessible kinematic range. The relativistic baryon wave functions of the quark-diquark bound system are used for the calculation of the decay matrix elements, the Isgur-Wise function, and decay rates in the heavy-quark limit.
Time-resolved doubly bent crystal x-ray spectrometer
Hockaday, M.P.; Wilke, M.D.; Blake, R.L.; Vaninetti, J.; Gray, N.T.; Nedrow, P.T.
1988-08-01
X-ray spectroscopy is an essential tool in high-temperature plasma research. We describe a time-resolved x-ray spectrometer suitable for measuring spectra in harsh environments common to many very high-energy density laboratory plasma sources. The spectrometer consisted of a doubly curved Si(111) crystal diffraction element, a WL-1201 (ZnO:Ga) phosphor, a coherent fiber-optic array, and two visible streak cameras. The spectrometer design described here has a minimum time resolution of 1.3 ns with 2.8-eV spectral resolution over a 200-eV-wide bandpass in the 6--7-keV region of the spectrum. Complete system spectral throughput calibrations were done at the Cornell High Energy Synchrotron (CHESS). Details of the design and calibration results are presented.
Time-resolved doubly bent crystal x-ray spectrometer
Hockaday, M.P.; Wilke, M.D.; Blake, R.L.; Vaninetti, J.; Gray, N.T.; Nedrow, P.T.
1988-01-01
X-ray spectroscopy is an essential tool in high temperature plasma research. We describe a time-resolved x-ray spectrometer suitable for measuring spectra in harsh environments common to many very high energy density laboratory plasma sources. The spectrometer consisted of a doubly curved Si(111) crystal diffraction element, a WL-1201 (ZnO:Ga) phosphor, a coherent fiber optic array, and two visible streak cameras. The spectrometer design described here has a minimum time resolution of 1.3 ns with 2.8 eV spectral resolution over a 200 eV wide bandpass in the 6-7 keV region of the spectrum. Complete system spectral throughput calibrations were done at the Cornell High Energy Synchrotron (CHESS). Details of the design and calibration results are presented. 5 refs., 5 figs.
Doubly Sparse Relevance Vector Machine for Continuous Facial Behavior Estimation.
Kaltwang, Sebastian; Todorovic, Sinisa; Pantic, Maja
2016-09-01
Certain inner feelings and physiological states like pain are subjective states that cannot be directly measured, but can be estimated from spontaneous facial expressions. Since they are typically characterized by subtle movements of facial parts, analysis of the facial details is required. To this end, we formulate a new regression method for continuous estimation of the intensity of facial behavior interpretation, called Doubly Sparse Relevance Vector Machine (DSRVM). DSRVM enforces double sparsity by jointly selecting the most relevant training examples (a.k.a. relevance vectors) and the most important kernels associated with facial parts relevant for interpretation of observed facial expressions. This advances prior work on multi-kernel learning, where sparsity of relevant kernels is typically ignored. Empirical evaluation on challenging Shoulder Pain videos, and the benchmark DISFA and SEMAINE datasets demonstrate that DSRVM outperforms competing approaches with a multi-fold reduction of running times in training and testing. PMID:26595911
Coherence and correlation in doubly excited heliumlike atoms
NASA Astrophysics Data System (ADS)
Burgdörfer, Joachim; Morgenstern, Reinhard
1988-12-01
We analyze properties of the density matrix of doubly excited two-electron systems formed in inelastic collisions. Formulas for the two-particle joint angular probability density, the angular correlation function, and the reduced single-particle density are derived. Of particular interest is the interplay between the intrinsic correlations of the stationary two-electron state and collisionally induced coherences. We focus on its effects on the correlated and single-particle motion of the electrons. If one chooses approximate stationary wave functions reflecting the approximate O(4)×O(4)⊃O(4) dynamical symmetry, a simple quasiclassical interpretation of coherence and correlation in terms of shapes and modes of the relative motion of Kepler orbits can be given. The present description is applied to recent experimental results by Van der Straten and Morgenstern [Comments At. Mol. Phys. 19, 243 (1986)].
Doubly magic nucleus (108)(270)Hs162.
Dvorak, J; Brüchle, W; Chelnokov, M; Dressler, R; Düllmann, Ch E; Eberhardt, K; Gorshkov, V; Jäger, E; Krücken, R; Kuznetsov, A; Nagame, Y; Nebel, F; Novackova, Z; Qin, Z; Schädel, M; Schausten, B; Schimpf, E; Semchenkov, A; Thörle, P; Türler, A; Wegrzecki, M; Wierczinski, B; Yakushev, A; Yeremin, A
2006-12-15
Theoretical calculations predict 270Hs (Z=108, N=162) to be a doubly magic deformed nucleus, decaying mainly by alpha-particle emission. In this work, based on a rapid chemical isolation of Hs isotopes produced in the 26Mg+248Cm reaction, we observed 15 genetically linked nuclear decay chains. Four chains were attributed to the new nuclide 270Hs, which decays by alpha-particle emission with Qalpha=9.02+/-0.03 MeV to 266Sg which undergoes spontaneous fission with a half-life of 444(-148)(+444) ms. A production cross section of about 3 pb was measured for 270Hs. Thus, 270Hs is the first nucleus for which experimental nuclear decay properties have become available for comparison with theoretical predictions of the N=162 shell stability. PMID:17280272
Exact Traveling Wave Solutions of a Higher-Dimensional Nonlinear Evolution Equation
NASA Astrophysics Data System (ADS)
Lee, Jonu; Sakthivel, Rathinasamy; Wazzan, Luwai
The exact traveling wave solutions of (4 + 1)-dimensional nonlinear Fokas equation is obtained by using three distinct methods with symbolic computation. The modified tanh-coth method is implemented to obtain single soliton solutions whereas the extended Jacobi elliptic function method is applied to derive doubly periodic wave solutions for this higher-dimensional integrable equation. The Exp-function method gives generalized wave solutions with some free parameters. It is shown that soliton solutions and triangular solutions can be established as the limits of the Jacobi doubly periodic wave solutions.
Absolute doubly differential bremsstrahlung cross sections from rare gas atoms
NASA Astrophysics Data System (ADS)
Portillo, Salvador
The absolute doubly differential bremsstrahlung cross section has been measured for 28 and 50 keV electrons incident on the rare gases Xe, Kr, Ar and Ne. The cross sections are differential with respect to energy and photon emission. A SiLi solid state detector measured data at 90° with respect to the beam line. A thorough analysis of the experimental systematic error yielded a high degree of confidence in the experimental data. The absolute bremsstrahlung doubly differential cross sections provided for a rigorous test of the normal bremsstrahlung theory, tabulated by Kissel, Quarles and Pratt1 (KQP) and of the SA theory2 that includes the contribution from polarization bremsstrahlung. To test the theories a comparison of the overall magnitude of the cross section as well as comparison of the photon energy dependence was carried out. The KQP theoretical values underestimated the magnitude of the cross section for all targets and for both energies. The SA values were in excellent agreement with the 28 keV data. For the 50keV data the fit was also very good. However, there were energy regions where there was a small discrepancy between the theory and the data. This suggests that the Polarization Bremsstrahlung (PB) mechanism does contribute to the overall spectrum and is detectable in this parameter space. 1Kissel, L., Quarles, C. A., Pratt, R. H., Atom. Data Nucl. Data Tables 28, 381 (1983). 2Avdonina N. B., Pratt, R. H., J. Phys. B: At. Mol. Opt. Phys. 32 4261 (1999).
Cao, Weihua; Tsiatis, Anastasios A; Davidian, Marie
2009-09-01
Considerable recent interest has focused on doubly robust estimators for a population mean response in the presence of incomplete data, which involve models for both the propensity score and the regression of outcome on covariates. The usual doubly robust estimator may yield severely biased inferences if neither of these models is correctly specified and can exhibit nonnegligible bias if the estimated propensity score is close to zero for some observations. We propose alternative doubly robust estimators that achieve comparable or improved performance relative to existing methods, even with some estimated propensity scores close to zero. PMID:20161511
Doubly charged CO2 clusters formed by ionization of doped helium nanodroplets☆
Daxner, Matthias; Denifl, Stephan; Scheier, Paul; Echt, Olof
2014-01-01
Helium nanodroplets are doped with carbon dioxide and ionized by electrons. Doubly charged cluster ions are, for the first time, identified based on their characteristic patterns of isotopologues. Thanks to the high mass resolution, large dynamic range, and a novel method to eliminate contributions from singly charged ions from the mass spectra, we are able to observe doubly charged cluster ions that are smaller than the ones reported in the past. The likely mechanism by which doubly charged ions are formed in doped helium droplets is discussed. PMID:25844051
Equation-of-motion coupled-cluster method for doubly ionized states with spin-orbit coupling
Wang, Zhifan; Hu, Shu; Guo, Jingwei; Wang, Fan
2015-04-14
In this work, we report implementation of the equation-of-motion coupled-cluster method for doubly ionized states (EOM-DIP-CC) with spin-orbit coupling (SOC) using a closed-shell reference. Double ionization potentials (DIPs) are calculated in the space spanned by 2h and 3h1p determinants with the EOM-DIP-CC approach at the CC singles and doubles level (CCSD). Time-reversal symmetry together with spatial symmetry is exploited to reduce computational effort. To circumvent the problem of unstable dianion references when diffuse basis functions are included, nuclear charges are scaled. Effect of this stabilization potential on DIPs is estimated based on results from calculations using a small basis set without diffuse basis functions. DIPs and excitation energies of some low-lying states for a series of open-shell atoms and molecules containing heavy elements with two unpaired electrons have been calculated with the EOM-DIP-CCSD approach. Results show that this approach is able to afford a reliable description on SOC splitting. Furthermore, the EOM-DIP-CCSD approach is shown to provide reasonable excitation energies for systems with a dianion reference when diffuse basis functions are not employed.
Ebrahimkhani, Sadegh
2016-07-01
Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme. PMID:27018145
Recent development of doubly curved crystal focusing optics and their applications for micro XRF
NASA Astrophysics Data System (ADS)
Chen, Zewu
1999-11-01
Three-dimensional focusing of x-rays can be achieved by doubly-curved crystals through diffraction from a small laboratory x-ray source. Recently it has been demonstrated that an intense monochromatic x-ray microprobe can be obtained with the use of a doubly-curved mica crystal. Due to monochromatic excitation using doubly-curved crystal optics, exceptionally low background has been demonstrated in the application to micro x-ray fluorescence (MXRF). Low background and high intensity gain significantly improve the detection limit for MXRF. In this paper, the focusing and diffraction properties of a doubly-curved Johann point-focusing crystal optic for Cu K(alpha) x-rays from a microfocus x-ray source is presented. Experimental data on spot size, beam intensity, effect of source position for the optics, and MXRF spectra are discussed.
Intrinsic Negative Mass from Nonlinearity
NASA Astrophysics Data System (ADS)
Di Mei, F.; Caramazza, P.; Pierangeli, D.; Di Domenico, G.; Ilan, H.; Agranat, A. J.; Di Porto, P.; DelRe, E.
2016-04-01
We propose and provide experimental evidence of a mechanism able to support negative intrinsic effective mass. The idea is to use a shape-sensitive nonlinearity to change the sign of the mass in the leading linear propagation equation. Intrinsic negative-mass dynamics is reported for light beams in a ferroelectric crystal substrate, where the diffusive photorefractive nonlinearity leads to a negative-mass Schrödinger equation. The signature of inverted dynamics is the observation of beams repelled from strongly guiding integrated waveguides irrespective of wavelength and intensity and suggests shape-sensitive nonlinearity as a basic mechanism leading to intrinsic negative mass.
High Performance Variable Speed Drive System and Generating System with Doubly Fed Machines
NASA Astrophysics Data System (ADS)
Tang, Yifan
Doubly fed machines are another alternative for variable speed drive systems. The doubly fed machines, including doubly fed induction machine, self-cascaded induction machine and doubly excited brushless reluctance machine, have several attractive advantages for variable speed drive applications, the most important one being the significant cost reduction with a reduced power converter rating. With a better understanding, improved machine design, flexible power converters and innovated controllers, the doubly fed machines could favorably compete for many applications, which may also include variable speed power generations. The goal of this research is to enhance the attractiveness of the doubly fed machines for both variable speed drive and variable speed generator applications. Recognizing that wind power is one of the favorable clean, renewable energy sources that can contribute to the solution to the energy and environment dilemma, a novel variable-speed constant-frequency wind power generating system is proposed. By variable speed operation, energy capturing capability of the wind turbine is improved. The improvement can be further enhanced by effectively utilizing the doubly excited brushless reluctance machine in slip power recovery configuration. For the doubly fed machines, a stator flux two -axis dynamic model is established, based on which a flexible active and reactive power control strategy can be developed. High performance operation of the drive and generating systems is obtained through advanced control methods, including stator field orientation control, fuzzy logic control and adaptive fuzzy control. System studies are pursued through unified modeling, computer simulation, stability analysis and power flow analysis of the complete drive system or generating system with the machine, the converter and the control. Laboratory implementations and tested results with a digital signal processor system are also presented.
Current diffusion in rail-gun conductors
Kerrisk, J.F.
1982-06-01
A method has been developed to analyze one- and two-dimensional, nonlinear current diffusion in rail-gun conductors. A nonlinear current-diffusion equation that accounts for the temperature dependence of electrical conductivity has been developed from Maxwell's equations. A finite-difference heat-transfer computer program was adapted to solve the current-diffusion and thermal-diffusion problems for rail-gun conductors in one and two dimensions. The nonlinear current-diffusion equation was also extended to account for the magnetic-field dependence of the magnetic permeability, thus allowing ferromagnetic materials to be considered. A one-dimensional finite-difference technique was developed for ferromagnetic materials. Two one-dimensional test problems that compare results with other analyses are discussed. A series of calculations of current density and rail temperature was done for various size rectangular rails. One analysis of current diffusion in a ferromagnetic material was also performed.
Fluid dynamics of double diffusive systems
Koseff, J.R.
1989-04-07
A study of mixing processes in doubly diffusive systems is being conducted. Continuous gradients of two diffusing components (heat and salinity in our case) are being used as initial conditions, and forcing is introduced by lateral heating and surface shear. The goals of the proposed work include: (1) quantification of the effects of finite amplitude disturbances on stable, double diffusive systems, particularly with respect to lateral heating, (2) development of an improved understanding of the physical phenomena present in wind-driven shear flows in double diffusive stratified environments, (3) increasing our knowledge-base on turbulent flow in stratified environments and how to represent it, and (4) formulation of a numerical code for such flows. The work is being carried out in an experimental facility which is located in the Stanford Environmental Fluid Mechanics Laboratory, and on laboratory minicomputers and CRAY computers. In particular we are focusing on the following key issues: (1) the formation and propagation of double diffusive intrusions away from a heated wall and the effects of lateral heating on the double diffusive system; (2) the interaction between the double diffusively influenced fluxes and the turbulence induced fluxes; (3) the measurement of heat and mass fluxes; and (4) the influence of double diffusive gradients on mixed layer deepening. 1 fig.
Approximate Solutions Of Equations Of Steady Diffusion
NASA Technical Reports Server (NTRS)
Edmonds, Larry D.
1992-01-01
Rigorous analysis yields reliable criteria for "best-fit" functions. Improved "curve-fitting" method yields approximate solutions to differential equations of steady-state diffusion. Method applies to problems in which rates of diffusion depend linearly or nonlinearly on concentrations of diffusants, approximate solutions analytic or numerical, and boundary conditions of Dirichlet type, of Neumann type, or mixture of both types. Applied to equations for diffusion of charge carriers in semiconductors in which mobilities and lifetimes of charge carriers depend on concentrations.
On nonlinear diffusion problems with strong degeneracy
NASA Astrophysics Data System (ADS)
Ammar, Kaouther
In this paper, we study the "triply" degenerate problem: b(-Δg(v)+divΦ(v)=f on Q:=(0,T)×Ω, b(v(0,ṡ))=b(v) on Ω and " g(v)=g(a) on some part of the boundary (0,T)×∂Ω," in the case of continuous nonhomogeneous and nonstationary boundary data a. The functions b,g are assumed to be continuous, locally Lipschitz, nondecreasing and to verify the normalization condition b(0)=g(0)=0 and the range condition R(b+g)=R. Using monotonicity and penalization methods, we prove existence of a weak renormalized entropy solution in the spirit of [K. Ammar, J. Carrillo, P. Wittbold, Scalar conservation laws with general boundary condition and continuous flux function, J. Differential Equations 228 (2006) 111-139].
Fragmentation network of doubly charged methionine: Interpretation using graph theory
NASA Astrophysics Data System (ADS)
Ha, D. T.; Yamazaki, K.; Wang, Y.; Alcamí, M.; Maeda, S.; Kono, H.; Martín, F.; Kukk, E.
2016-09-01
The fragmentation of doubly charged gas-phase methionine (HO2CCH(NH2)CH2CH2SCH3) is systematically studied using the self-consistent charge density functional tight-binding molecular dynamics (MD) simulation method. We applied graph theory to analyze the large number of the calculated MD trajectories, which appears to be a highly effective and convenient means of extracting versatile information from the large data. The present theoretical results strongly concur with the earlier studied experimental ones. Essentially, the dication dissociates into acidic group CO2H and basic group C4NSH10. The former may carry a single or no charge and stays intact in most cases, whereas the latter may hold either a single or a double charge and tends to dissociate into smaller fragments. The decay of the basic group is observed to follow the Arrhenius law. The dissociation pathways to CO2H and C4NSH10 and subsequent fragmentations are also supported by ab initio calculations.
Brushless Doubly-Fed Machine system development program, phase 3
NASA Astrophysics Data System (ADS)
Alexander, G. C.; Spee, R.; Wallace, A. K.
Since the inception of the Brushless Doubly-Fed Machine (BDFM) System Development Program in 1989, the value of BDFM technology has become apparent. The BDFM provides for adjustable speed, synchronous operation while keeping costs associated with the required power conversion equipment lower than in competing technologies. This provides for an advantage in initial as well as maintenance expenses over conventional drive system. Thus, the BDFM enables energy efficient, adjustable speed process control for applications where established drive technology has not been able to deliver satisfactory returns on investment. At the same time, the BDFM challenges conventional drive technologies in established markets by providing for improved performance at lower cost. BDFM converter rating is kept at a minimum, which significantly improves power quality at the utility interface over competing power conversion equipment. In summary, BDFM technology can be expected to provide significant benefits to utilities as well as their customers. This report discusses technical research and development activities related to Phase 3 of the BDFM System Development Program, including work made possible by supplemental funds for laboratory improvement and prototype construction.
Doubly robust estimation in missing data and causal inference models.
Bang, Heejung; Robins, James M
2005-12-01
The goal of this article is to construct doubly robust (DR) estimators in ignorable missing data and causal inference models. In a missing data model, an estimator is DR if it remains consistent when either (but not necessarily both) a model for the missingness mechanism or a model for the distribution of the complete data is correctly specified. Because with observational data one can never be sure that either a missingness model or a complete data model is correct, perhaps the best that can be hoped for is to find a DR estimator. DR estimators, in contrast to standard likelihood-based or (nonaugmented) inverse probability-weighted estimators, give the analyst two chances, instead of only one, to make a valid inference. In a causal inference model, an estimator is DR if it remains consistent when either a model for the treatment assignment mechanism or a model for the distribution of the counterfactual data is correctly specified. Because with observational data one can never be sure that a model for the treatment assignment mechanism or a model for the counterfactual data is correct, inference based on DR estimators should improve upon previous approaches. Indeed, we present the results of simulation studies which demonstrate that the finite sample performance of DR estimators is as impressive as theory would predict. The proposed method is applied to a cardiovascular clinical trial.
Study of doubly strange systems using stored antiprotons
NASA Astrophysics Data System (ADS)
Singh, B.; Erni, W.; Krusche, B.; Steinacher, M.; Walford, N.; Liu, B.; Liu, H.; Liu, Z.; Shen, X.; Wang, C.; Zhao, J.; Albrecht, M.; Erlen, T.; Fink, M.; Heinsius, F.; Held, T.; Holtmann, T.; Jasper, S.; Keshk, I.; Koch, H.; Kopf, B.; Kuhlmann, M.; Kümmel, M.; Leiber, S.; Mikirtychyants, M.; Musiol, P.; Mustafa, A.; Pelizäus, M.; Pychy, J.; Richter, M.; Schnier, C.; Schröder, T.; Sowa, C.; Steinke, M.; Triffterer, T.; Wiedner, U.; Ball, M.; Beck, R.; Hammann, C.; Ketzer, B.; Kube, M.; Mahlberg, P.; Rossbach, M.; Schmidt, C.; Schmitz, R.; Thoma, U.; Urban, M.; Walther, D.; Wendel, C.; Wilson, A.; Bianconi, A.; Bragadireanu, M.; Caprini, M.; Pantea, D.; Patel, B.; Czyzycki, W.; Domagala, M.; Filo, G.; Jaworowski, J.; Krawczyk, M.; Lisowski, E.; Lisowski, F.; Michałek, M.; Poznański, P.; Płażek, J.; Korcyl, K.; Kozela, A.; Kulessa, P.; Lebiedowicz, P.; Pysz, K.; Schäfer, W.; Szczurek, A.; Fiutowski, T.; Idzik, M.; Mindur, B.; Przyborowski, D.; Swientek, K.; Biernat, J.; Kamys, B.; Kistryn, S.; Korcyl, G.; Krzemien, W.; Magiera, A.; Moskal, P.; Psyzniak, A.; Rudy, Z.; Salabura, P.; Smyrski, J.; Strzempek, P.; Wronska, A.; Augustin, I.; Böhm, R.; Lehmann, I.; Nicmorus Marinescu, D.; Schmitt, L.; Varentsov, V.; Al-Turany, M.; Belias, A.; Deppe, H.; Dzhygadlo, R.; Ehret, A.; Flemming, H.; Gerhardt, A.; Götzen, K.; Gromliuk, A.; Gruber, L.; Karabowicz, R.; Kliemt, R.; Krebs, M.; Kurilla, U.; Lehmann, D.; Löchner, S.; Lühning, J.; Lynen, U.; Orth, H.; Patsyuk, M.; Peters, K.; Saito, T.; Schepers, G.; Schmidt, C. J.; Schwarz, C.; Schwiening, J.; Täschner, A.; Traxler, M.; Ugur, C.; Voss, B.; Wieczorek, P.; Wilms, A.; Zühlsdorf, M.; Abazov, V. M.; Alexeev, G.; Arefiev, A.; Astakhov, V. I.; Barabanov, M. Yu.; Batyunya, B. V.; Davydov, Yu. I.; Dodokhov, V. Kh.; Efremov, A. A.; Fechtchenko, A.; Fedunov, A. G.; Galoyan, A.; Grigoryan, S.; Koshurnikov, E. K.; Lobanov, V. I.; Lobanov, Y. Yu.; Makarov, A. F.; Malinina, L. V.; Malyshev, V. L.; Olshevskiy, A.; Perevalova, E.; Piskun, A. A.; Pocheptsov, T.; Pontecorvo, G.; Rodionov, V.; Rogov, Y.; Salmin, R.; Samartsev, A.; Sapozhnikov, M. G.; Shabratova, G.; Skachkov, N. B.; Skachkova, A. N.; Strokovsky, E. A.; Suleimanov, M.; Teshev, R.; Tokmenin, V.; Uzhinsky, V.; Vodopyanov, A.; Zaporozhets, S. A.; Zhuravlev, N. I.; Zorin, A. G.; Branford, D.; Glazier, D.; Watts, D.; Böhm, M.; Britting, A.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Dobbs, S.; Seth, K.; Tomaradze, A.; Xiao, T.; Bettoni, D.; Carassiti, V.; Cotta Ramusino, A.; Dalpiaz, P.; Drago, A.; Fioravanti, E.; Garzia, I.; Savriè, M.; Akishina, V.; Kisel, I.; Kozlov, G.; Pugach, M.; Zyzak, M.; Gianotti, P.; Guaraldo, C.; Lucherini, V.; Bersani, A.; Bracco, G.; Macri, M.; Parodi, R. F.; Biguenko, K.; Brinkmann, K.; Di Pietro, V.; Diehl, S.; Dormenev, V.; Drexler, P.; Düren, M.; Etzelmüller, E.; Galuska, M.; Gutz, E.; Hahn, C.; Hayrapetyan, A.; Kesselkaul, M.; Kühn, W.; Kuske, T.; Lange, J. S.; Liang, Y.; Metag, V.; Nanova, M.; Nazarenko, S.; Novotny, R.; Quagli, T.; Reiter, S.; Rieke, J.; Rosenbaum, C.; Schmidt, M.; Schnell, R.; Stenzel, H.; Thöring, U.; Ullrich, M.; Wagner, M. N.; Wasem, T.; Wohlfarth, B.; Zaunick, H.; Ireland, D.; Rosner, G.; Seitz, B.; Deepak, P. N.; Kulkarni, A.; Apostolou, A.; Babai, M.; Kavatsyuk, M.; Lemmens, P.; Lindemulder, M.; Loehner, H.; Messchendorp, J.; Schakel, P.; Smit, H.; Tiemens, M.; van der Weele, J. C.; Veenstra, R.; Vejdani, S.; Dutta, K.; Kalita, K.; Kumar, A.; Roy, A.; Sohlbach, H.; Bai, M.; Bianchi, L.; Büscher, M.; Cao, L.; Cebulla, A.; Dosdall, R.; Gillitzer, A.; Goldenbaum, F.; Grunwald, D.; Herten, A.; Hu, Q.; Kemmerling, G.; Kleines, H.; Lehrach, A.; Nellen, R.; Ohm, H.; Orfanitski, S.; Prasuhn, D.; Prencipe, E.; Pütz, J.; Ritman, J.; Schadmand, S.; Sefzick, T.; Serdyuk, V.; Sterzenbach, G.; Stockmanns, T.; Wintz, P.; Wüstner, P.; Xu, H.; Zambanini, A.; Li, S.; Li, Z.; Sun, Z.; Xu, H.; Rigato, V.; Isaksson, L.; Achenbach, P.; Corell, O.; Denig, A.; Distler, M.; Hoek, M.; Karavdina, A.; Lauth, W.; Liu, Z.; Merkel, H.; Müller, U.; Pochodzalla, J.; Schlimme, S.; Sfienti, C.; Thiel, M.; Ahmadi, H.; Ahmed, S.; Bleser, S.; Capozza, L.; Cardinali, M.; Dbeyssi, A.; Deiseroth, M.; Feldbauer, F.; Fritsch, M.; Fröhlich, B.; Jasinski, P.; Kang, D.; Khaneft, D.; Klasen, R.; Leithoff, H. H.; Lin, D.; Maas, F.; Maldaner, S.; Martìnez Rojo, M.; Marta, M.; Michel, M.; Mora Espì, M. C.; Morales Morales, C.; Motzko, C.; Nerling, F.; Noll, O.; Pflüger, S.; Pitka, A.; Rodríguez Piñeiro, D.; Sanchez Lorente, A.; Steinen, M.; Valente, R.; Weber, T.; Zambrana, M.; Zimmermann, I.; Fedorov, A.; Korjik, M.; Missevitch, O.; Boukharov, A.; Malyshev, O.; Marishev, I.; Balanutsa, P.; Balanutsa, V.; Chernetsky, V.; Demekhin, A.; Dolgolenko, A.; Fedorets, P.; Gerasimov, A.; Goryachev, V.; Chandratre, V.; Datar, V.; Dutta, D.; Jha, V.; Kumawat, H.; Mohanty, A. K.; Parmar, A.; Roy, B.; Sonika, G.; Fritzsch, C.; Grieser, S.; Hergemöller, A. K.; Hetz, B.; Hüsken, N.; Khoukaz, A.; Wessels, J. P.; Khosonthongkee, K.; Kobdaj, C.; Limphirat, A.; Srisawad, P.; Yan, Y.; Barnyakov, M.; Barnyakov, A. Yu.; Beloborodov, K.; Blinov, A. E.; Blinov, V. E.; Bobrovnikov, V. S.; Kononov, S.; Kravchenko, E. A.; Kuyanov, I. A.; Martin, K.; Onuchin, A. P.; Serednyakov, S.; Sokolov, A.; Tikhonov, Y.; Atomssa, E.; Kunne, R.; Marchand, D.; Ramstein, B.; Van de Wiele, J.; Wang, Y.; Boca, G.; Costanza, S.; Genova, P.; Montagna, P.; Rotondi, A.; Abramov, V.; Belikov, N.; Bukreeva, S.; Davidenko, A.; Derevschikov, A.; Goncharenko, Y.; Grishin, V.; Kachanov, V.; Kormilitsin, V.; Levin, A.; Melnik, Y.; Minaev, N.; Mochalov, V.; Morozov, D.; Nogach, L.; Poslavskiy, S.; Ryazantsev, A.; Ryzhikov, S.; Semenov, P.; Shein, I.; Uzunian, A.; Vasiliev, A.; Yakutin, A.; Tomasi-Gustafsson, E.; Roy, U.; Yabsley, B.; Belostotski, S.; Gavrilov, G.; Izotov, A.; Manaenkov, S.; Miklukho, O.; Veretennikov, D.; Zhdanov, A.; Makonyi, K.; Preston, M.; Tegner, P.; Wölbing, D.; Bäck, T.; Cederwall, B.; Rai, A. K.; Godre, S.; Calvo, D.; Coli, S.; De Remigis, P.; Filippi, A.; Giraudo, G.; Lusso, S.; Mazza, G.; Mignone, M.; Rivetti, A.; Wheadon, R.; Balestra, F.; Iazzi, F.; Introzzi, R.; Lavagno, A.; Olave, J.; Amoroso, A.; Bussa, M. P.; Busso, L.; De Mori, F.; Destefanis, M.; Fava, L.; Ferrero, L.; Greco, M.; Hu, J.; Lavezzi, L.; Maggiora, M.; Maniscalco, G.; Marcello, S.; Sosio, S.; Spataro, S.; Birsa, R.; Bradamante, F.; Bressan, A.; Martin, A.; Calen, H.; Ikegami Andersson, W.; Johansson, T.; Kupsc, A.; Marciniewski, P.; Papenbrock, M.; Pettersson, J.; Schönning, K.; Wolke, M.; Galnander, B.; Diaz, J.; Pothodi Chackara, V.; Chlopik, A.; Kesik, G.; Melnychuk, D.; Slowinski, B.; Trzcinski, A.; Wojciechowski, M.; Wronka, S.; Zwieglinski, B.; Bühler, P.; Marton, J.; Steinschaden, D.; Suzuki, K.; Widmann, E.; Zmeskal, J.; Gerl, Jürgen; Kojouharov, Ivan; Kojouharova, Jasmina
2016-10-01
Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the P ‾ ANDA experiment at FAIR. For the first time, high resolution γ-spectroscopy of doubly strange ΛΛ-hypernuclei will be performed, thus complementing measurements of ground state decays of ΛΛ-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Ξ--atoms will be feasible and even the production of Ω--atoms will be within reach. The latter might open the door to the | S | = 3 world in strangeness nuclear physics, by the study of the hadronic Ω--nucleus interaction. For the first time it will be possible to study the behavior of Ξ‾+ in nuclear systems under well controlled conditions.
Fragmentation network of doubly charged methionine: Interpretation using graph theory.
Ha, D T; Yamazaki, K; Wang, Y; Alcamí, M; Maeda, S; Kono, H; Martín, F; Kukk, E
2016-09-01
The fragmentation of doubly charged gas-phase methionine (HO2CCH(NH2)CH2CH2SCH3) is systematically studied using the self-consistent charge density functional tight-binding molecular dynamics (MD) simulation method. We applied graph theory to analyze the large number of the calculated MD trajectories, which appears to be a highly effective and convenient means of extracting versatile information from the large data. The present theoretical results strongly concur with the earlier studied experimental ones. Essentially, the dication dissociates into acidic group CO2H and basic group C4NSH10. The former may carry a single or no charge and stays intact in most cases, whereas the latter may hold either a single or a double charge and tends to dissociate into smaller fragments. The decay of the basic group is observed to follow the Arrhenius law. The dissociation pathways to CO2H and C4NSH10 and subsequent fragmentations are also supported by ab initio calculations. PMID:27608997
Anomalous Diffusion Mediated by Atom Deposition into a Porous Substrate
Brault, Pascal; Bauchire, Jean-Marc; Josserand, Christophe; Caillard, Amaeel; Charles, Christine; Boswell, Rod W.
2009-01-30
Constant flux atom deposition into a porous medium is shown to generate a dense overlayer and a diffusion profile. Scaling analysis shows that the overlayer acts as a dynamic control for atomic diffusion in the porous substrate. This is modeled by generalizing the porous diffusion equation with a time-dependent diffusion coefficient equivalent to a nonlinear rescaling of time.
Twofold PT symmetry in doubly exponential optical lattices
NASA Astrophysics Data System (ADS)
Cole, J. T.; Makris, K. G.; Musslimani, Z. H.; Christodoulides, D. N.; Rotter, S.
2016-01-01
We introduce a family of non-Hermitian optical potentials that are given in terms of double-exponential periodic functions. The center of PT symmetry is not around zero and the potential satisfies a shifted PT -symmetry relation at two distinct locations. Motivated by wave transmission through thin phase screens and gratings, we examine these refractive index modulations from the perspective of optical lattices that are homogeneous along the propagation direction. The diffraction dynamics, abrupt phase transitions in the eigenvalue spectrum, and exceptional points in the band structure are examined in detail. In addition, the nonlinear properties of wave propagation in Kerr nonlinearity media are studied. In particular, coherent structures such as lattice solitons are numerically identified by applying the spectral renormalization method. The spatial symmetries of such lattice solitons follow the shifted PT -symmetric relations. Furthermore, such lattice solitons have a power threshold and their linear and nonlinear stabilities are critically dependent on their spatial symmetry point.
Structural Heterogeneity of Doubly-Charged Peptide b-Ions
NASA Astrophysics Data System (ADS)
Li, Xiaojuan; Huang, Yiqun; O'Connor, Peter B.; Lin, Cheng
2011-02-01
Performing collisionally activated dissociation (CAD) and electron capture dissociation (ECD) in tandem has shown great promise in providing comprehensive sequence information that was otherwise unobtainable by using either fragmentation method alone or in duet. However, the general applicability of this MS3 approach in peptide sequencing may be undermined by the formation of non-direct sequence ions, as sometimes observed under CAD, particularly when multiple stages of CAD are involved. In this study, varied-sized doubly-charged b-ions from three tachykinin peptides were investigated by ECD. Sequence scrambling was observed in ECD of all b-ions from neurokinin A (HKTDSFVGLM-NH2), suggesting the presence of N- and C-termini linked macro-cyclic conformers. On the contrary, none of the b-ions from eledoisin (pEPSKDAFIGLM-NH2) produced non-direct sequence ions under ECD, as it does not contain a free N-terminal amino group. ECD of several b-ions from Substance P (RPKPQQFFGLM-NH2) showed series of cm-Lys fragment ions which suggested that the macro-cyclic structure may also be formed by connecting the C-terminal carbonyl group and the ɛ-amino group of the lysine side chain. Theoretical investigation of selected Substance P b-ions revealed several low energy conformers, including both linear oxazolones and macro-ring structures, in corroboration with the experimental observation. This study showed that a b-ion may exist as a mixture of several forms, with their propensities influenced by its N-terminus, length, and certain side-chain groups. Further, the presence of several macro-cyclic structures may result in erroneous sequence assignment when the combined CAD and ECD methods are used in peptide sequencing.
Simultaneous marginal survival estimators when doubly censored data is present.
Julià, Olga; Gómez, Guadalupe
2011-07-01
A doubly censoring scheme occurs when the lifetimes T being measured,from a well-known time origin, are exactly observed within a window [L, R] of observational time and are otherwise censored either from above (right-censored observations)or below (left-censored observations). Sample data consists on the pairs (U, δ)where U = min{R, max{T, L}} and δ indicates whether T is exactly observed (δ = 0),right-censored (δ = 1) or left-censored (δ = −1). We are interested in the estimation of the marginal behaviour of the three random variables T, L and R based on the observed pairs (U, δ).We propose new nonparametric simultaneous marginal estimators Ŝ(T) , Ŝ(L) and Ŝ(R) for the survival functions of T, L and R, respectively, by means of an inverse-probability-of-censoring approach. The proposed estimators Ŝ(T) , Ŝ(L) and Ŝ(R) are not computationally intensive, generalize the empirical survival estimator and reduce to the Kaplan-Meier estimator in the absence of left-censored data. Furthermore,Ŝ(T) is equivalent to a self-consistent estimator, is uniformly strongly consistent and asymptotically normal. The method is illustrated with data from a cohort of drug users recruited in a detoxification program in Badalona (Spain). For these data we estimate the survival function for the elapsed time from starting IV-drugs to AIDS diagnosis, as well as the potential follow-up time. A simulation study is discussed to assess the performance of the three survival estimators for moderate sample sizes and different censoring levels.
The Torsional Spectrum of Doubly Deuterated Methanol CHD_2OH
NASA Astrophysics Data System (ADS)
Ndao, M.; Coudert, L. H.; Kwabia Tchana, F.; Barros, J.; Margulès, L.; Manceron, Laurent; Roy, P.
2014-06-01
Although the torsional spectrum of several isotopic species of methanol with a symmetrical CH_3 or CD_3 was analyzed some time ago, it is recently, and only for the monodeuterated species CH_2DOH, that such an analysis was extended to the case of an asymmetrical methyl group. In this talk, based on a Fourier transform high-resolution spectrum recorded in the 20 to 670 wn region, the first analysis of the torsional spectrum of doubly deuterated methanol CHD_2OH will be presented. The Q branch of many torsional subbands could be observed and their assignment was initiated using a theoretical torsion-rotation spectrum computed with an approach accounting for the torsion-rotation Coriolis coupling and for the dependence of the generalized inertia tensor on the angle of internal rotation. 46 torsional subbands were thus assigned. For 28 of them, their rotational structure could be assigned and fitted using an effective Hamiltonian expressed as a J(J+1) expansion; and for 2 of them microwave transitions within the lower torsional level could also be included in the analysis. In several cases these analysis revealed that the torsional levels are strongly perturbed. In the talk, the torsional parameters retrieved in the analysis of the torsional subband centers will be discussed. The results of the analysis of the rotational structure of the torsional subbands will be presented and we will also try to understand the nature of the perturbations. At last, preliminary results about the analysis of the microwave spectrum will be presented. El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. 135 (2011) 194309 Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spectrosc. 256 (2009) 204 Quade, Liu, Mukhopadhyay, and Su, J. Mol. Spectrosc. 192 (1998) 378 Pearson, Yu, and Drouin, J. Mol. Spectrosc. 280 (2012) 119
Nonlinear differential equations
Dresner, L.
1988-01-01
This report is the text of a graduate course on nonlinear differential equations given by the author at the University of Wisconsin-Madison during the summer of 1987. The topics covered are: direction fields of first-order differential equations; the Lie (group) theory of ordinary differential equations; similarity solutions of second-order partial differential equations; maximum principles and differential inequalities; monotone operators and iteration; complementary variational principles; and stability of numerical methods. The report should be of interest to graduate students, faculty, and practicing scientists and engineers. No prior knowledge is required beyond a good working knowledge of the calculus. The emphasis is on practical results. Most of the illustrative examples are taken from the fields of nonlinear diffusion, heat and mass transfer, applied superconductivity, and helium cryogenics.
Nonlinear optics and nonlinear dynamics
NASA Astrophysics Data System (ADS)
Chen, C. H.
1990-08-01
The author was invited by the Institute of Atomic and Molecular Sciences, Academia Sinica, in Taiwan to give six lectures on nonlinear optics. The participants included graduate students, postdoctoral fellows, research staff, and professors from several research organizations and universities. Extensive discussion followed each lecture. Since both the Photophysics Group at Oak Ridge National Laboratory (ORNL) and Institute of Atomic and Molecular Sciences in Taiwan have been actively participating in nonlinear optics research, the discussions are very beneficial to ORNL programs. The author also visited several laboratories at IAMS to exchange research ideas on nonlinear optics.
Comparison of doubly labeled water with respirometry at low- and high-activity levels
Westerterp, K.R.; Brouns, F.; Saris, W.H.; ten Hoor, F.
1988-07-01
In previous studies the doubly labeled water method for measuring energy expenditure in free-living humans has been validated against respirometry under sedentary conditions. In the present investigation, energy expenditure is measured simultaneously with doubly labeled water and respirometry at low- and high-activity levels. Over 6 days, five subjects were measured doing mainly sedentary activities like desk work; their average daily metabolic rate was 1.40 +/- 0.09 (SD) times sleeping metabolic rate. Four subjects were measured twice over 3.5 days, including 2 days with heavy bicycle ergometer work, resulting in an average daily metabolic rate of 2.61 +/- 0.25 (SD) times sleeping metabolic rate. At the low-activity level, energy expenditures from the doubly labeled water method were on the average 1.4 +/- 3.9% (SD) larger than those from respirometry. At the high-activity level, the doubly labeled water method yielded values that were 1.0 +/- 7.0% (SD) lower than those from respirometry. Results demonstrate the utility of the doubly labeled water method for the determination of energy expenditure in the range of activity levels in daily life.
The Doubly Labeled Water Method for Measuring Human Energy Expenditure: Adaptations for Spaceflight
NASA Technical Reports Server (NTRS)
Schulz, Leslie O.
1991-01-01
It is essential to determine human energy requirements in space, and the doubly labeled water method has been identified as the most appropriate means of indirect calorimetry to meet this need. The method employs naturally occurring, stable isotopes of hydrogen (H-2, deuterium) and oxygen (O-18) which, after dosing, mix with body water. The deuterium is lost from the body as water while the O-18 is eliminated as both water and CO2. The difference between the two isotope elimination rates is therefore a measure of CO2 production and hence energy expenditure. Spaceflight will present a unique challenge to the application of the doubly labeled water method. Specifically, interpretation of doubly labeled water results assumes that the natural abundance or 'background' levels of the isotopes remain constant during the measurement interval. To address this issue, an equilibration model will be developed in an ongoing ground-based study. As energy requirements of women matched to counterparts in the Astronauts Corps are being determined by doubly labeled water, the baseline isotope concentration will be changed by consumption of 'simulated Shuttle water' which is artificially enriched. One group of subjects will be equilibrated on simulated Shuttle water prior to energy determinations by doubly labeled water while the others will consume simulated Shuttle water after dosing. This process will allow us to derive a prediction equation to mathematically model the effect of changing background isotope concentrations.
NASA Astrophysics Data System (ADS)
Fukuyama, Hidenao
Recent advances of magnetic resonance imaging have been described, especially stressed on the diffusion sequences. We have recently applied the diffusion sequence to functional brain imaging, and found the appropriate results. In addition to the neurosciences fields, diffusion weighted images have improved the accuracies of clinical diagnosis depending upon magnetic resonance images in stroke as well as inflammations.
(ggr, 2ggr) studies on doubly excited states of molecular hydrogen
NASA Astrophysics Data System (ADS)
Odagiri, Takeshi; Murata, Makoto; Kato, Masahiro; Kouchi, Noriyuki
2004-10-01
The doubly differential cross sections for the emission of two Lyman-agr photons in photoexcitation of H2 have been measured as a function of incident photon energy in the range of 30-44 eV with a photon-photon coincidence technique. A cross section curve that is free from ionization and thus is attributed entirely to the doubly excited states of H2 has been obtained for the first time. A simple theoretical calculation based on the reflection approximation and semiclassical treatment of the decay dynamics in the Q21Pgru(1) state of H2 has reproduced well the experimental cross section curve. It has been shown that this method, the (ggr, 2ggr) method, is an excellent tool for investigating spectroscopy and dynamics of doubly or multiply excited molecules.
Three-loop neutrino mass model with doubly charged particles from isodoublets
NASA Astrophysics Data System (ADS)
Okada, Hiroshi; Yagyu, Kei
2016-01-01
We propose a new type of a three-loop induced neutrino mass model with dark matter candidates which are required for the neutrino mass generation. The smallness of neutrino masses can be naturally explained without introducing super heavy particles, namely, much heavier than a TeV scale and quite small couplings as compared to the gauge couplings. We find that as a bonus, the anomaly of the muon anomalous magnetic moment can simultaneously be explained by loop effects of new particles. In our model, there are doubly charged scalar bosons and leptons from isospin doublet fields which give characteristic collider signatures. In particular, the doubly charged scalar bosons can decay into the same-sign dilepton with its chirality of both right-handed or left- and right-handed. This can be a smoking gun signature to identify our model and be useful to distinguish other models with doubly charged scalar bosons at collider experiments.
In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D; Leung, Daniel; Liu, Norman; Meadows, Brian K; Gordon, Frank; Bulsara, Adi R; Palacios, Antonio
2012-12-01
The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.
NASA Astrophysics Data System (ADS)
Haslam, Michael C.
The primary aim of this thesis is to investigate the physical processes related to the stability of steep gravity waves, and their effect on the scattering of electromagnetic waves. It has been known for some time that periodic water waves are subject to a variety of shape-altering instabilities. It is generally believed that a certain class of these instabilities, which is relevant to steep waves, is responsible for spilling breakers. Empirical and theoretical research on these instabilities has suggested that the dominant mechanisms in nonlinear interactions in the wave field result in three-dimensional periodic structures. This fortuitous result allows us to treat the resulting surface as an optical grating, thus capturing the multi-path reflection effects (to which sea clutter is often attributed) in an exact solution. Additionally, effects such as shadowing, and other complexities, are included. An extended boundary condition method, commonly used in optical studies, is formulated to compute the scattering of an electromagnetic plane wave incident upon an arbitrary doubly periodic surface. This particular generalization of the method, which we provide for the first time, allows for the exact calculation of the fields corresponding to a linear, isotropic, conducting, dielectric scattering medium. Results from commonly-used test cases compare very favorably with those from other methods presented in the literature. The full water wave equations are solved numerically, and highly accurate solutions corresponding to three-dimensional steep wave instabilities are obtained. The scattered electromagnetic fields resulting from these profiles are then computed using the extended boundary condition method. The computational requirements, however, are large, and we have implemented the method in parallel on a Sharcnet Canada high-performance 144-processor cluster. We believe that we are the first to propose that steep wave instabilities may trigger anomalous returns in
Vertical Diffusivities of Active and Passive Tracers
NASA Technical Reports Server (NTRS)
Canuto, V. M.; Cheng, Y.; Howard, A. M.
2010-01-01
The climate models that include a carbon-cycle need the vertical diffusivity of a passive tracer. Since an expression for the latter is not available, it has been common practice to identify it with that of salt. The identification is questionable since T, S are active, not passive tracers. We present the first derivation of the diffusivity of a passive tracer in terms of Ri (Richardson number) and Rq (density ratio, ratio of salinity over temperature z-gradients). The following results have emerged: (a) The passive tracer diffusivity is an algebraic function of Ri, Rq. (b) In doubly stable regimes (DS, partial derivative of T with respect to z > 0, partial derivative of S with respect to z < 0), the passive scalar diffusivity is nearly the same as that of salt/heat for any values of Rq < 0 and Ri > 0. (c) In DC regimes (diffusive convection, partial derivative of T with respect to z < 0, partial derivative of S with respect to z < 0, Rq > 1), the passive scalar diffusivity is larger than that of salt. At Ri = O(1), it can be more than twice as large. (d) In SF regimes (salt fingers, partial derivative of T with respect to z > 0, partial derivative of S with respect to z > 0, Rq < 1), the passive scalar diffusivity is smaller than that of salt. At Ri = O(1), it can be less than half of it. (e) The passive tracer diffusivity predicted at the location of NATRE (North Atlantic Tracer Release Experiment) is discussed. (f) Perhaps the most relevant conclusion is that the common identification of the tracer diffusivity with that of salt is valid only in DS regimes. In the Southern Ocean, where there is the largest CO2 absorption, the dominant regime is diffusive convection discussed in (c) above.
Dynamic stability of a doubly quantized vortex in a three-dimensional condensate
Lundh, Emil; Nilsen, Halvor M.
2006-12-15
The Bogoliubov equations are solved for a three-dimensional Bose-Einstein condensate containing a doubly quantized vortex, trapped in a harmonic potential. Complex frequencies, signifying dynamical instability, are found for certain ranges of parameter values. The existence of alternating windows of stability and instability, respectively, is explained qualitatively and quantitatively using variational calculus and direct numerical solutions. It is seen that the windows of stability disappear in the limit of a cigar-shaped condensate, which is consistent with recent experimental results on the lifetime of a doubly quantized vortex in that regime.
Replicator dynamics with diffusion on multiplex networks
NASA Astrophysics Data System (ADS)
Requejo, R. J.; Díaz-Guilera, A.
2016-08-01
In this study we present an extension of the dynamics of diffusion in multiplex graphs, which makes the equations compatible with the replicator equation with mutations. We derive an exact formula for the diffusion term, which shows that, while diffusion is linear for numbers of agents, it is necessary to account for nonlinear terms when working with fractions of individuals. We also derive the transition probabilities that give rise to such macroscopic behavior, completing the bottom-up description. Finally, it is shown that the usual assumption of constant population sizes induces a hidden selective pressure due to the diffusive dynamics, which favors the increase of fast diffusing strategies.
Replicator dynamics with diffusion on multiplex networks.
Requejo, R J; Díaz-Guilera, A
2016-08-01
In this study we present an extension of the dynamics of diffusion in multiplex graphs, which makes the equations compatible with the replicator equation with mutations. We derive an exact formula for the diffusion term, which shows that, while diffusion is linear for numbers of agents, it is necessary to account for nonlinear terms when working with fractions of individuals. We also derive the transition probabilities that give rise to such macroscopic behavior, completing the bottom-up description. Finally, it is shown that the usual assumption of constant population sizes induces a hidden selective pressure due to the diffusive dynamics, which favors the increase of fast diffusing strategies. PMID:27627311
Reaction-diffusion waves in biology.
Volpert, V; Petrovskii, S
2009-12-01
The theory of reaction-diffusion waves begins in the 1930s with the works in population dynamics, combustion theory and chemical kinetics. At the present time, it is a well developed area of research which includes qualitative properties of travelling waves for the scalar reaction-diffusion equation and for system of equations, complex nonlinear dynamics, numerous applications in physics, chemistry, biology, medicine. This paper reviews biological applications of reaction-diffusion waves. PMID:20416847
Wang, Kun-Peng; Guo, Dong-Sheng; Zhao, Hong-Xia; Liu, Yu
2014-04-01
A water-soluble supramolecular polymer with a high degree of polymerization and viscosity has been constructed based on the strong host-guest interaction between p-sulfonatocalix[4]arenes (SC4As) and viologen. A homoditopic doubly ethyl-bridged bis(p-sulfonatocalix[4]arene) (d-SC4A) was prepared and its binding behavior towards methyl viologen compared with the singly ethyl-bridged bis(p-sulfonatocalix[4]arene) (s-SC4A) by NMR spectroscopy and isothermal titration calorimetry. By employing a viologen dimer (bisMV(4+)) as the homoditopic guest, two linear AA/BB-type supramolecular polymers, d-SC4A⊃bisMV(4+) and s-SC4A⊃bisMV(4+), were successfully constructed. Compared with s-SC4A⊃bisMV(4+), d-SC4A⊃bisMV(4+) shows much higher solubility and viscosity, and has also been characterized by viscosity, diffusion-ordered NMR spectroscopy, dynamic light scattering, and atomic force microscopy measurements. Furthermore, the polymer is responsive to electrostimulus as viologen is electroactive, which was studied by cyclic voltammetry. This study represents a proof-of-principle as the polymer can potentially be applied as a self-healing and degradable polymeric material.
Measuring doubly 13C-substituted ethane by mass spectrometry
NASA Astrophysics Data System (ADS)
Clog, M.; Ling, C.; Eiler, J. M.
2012-12-01
Ethane (C2H6) is present in non-negligible amounts in most natural gas reservoirs and is used to produce ethylene for petrochemical industries. It is one of the by-products of lipid metabolism and is the arguably simplest molecule that can manifest multiple 13C substitutions. There are several plausible controls on the relative abundances of 13C2H6 in natural gases: thermodynamically controlled homogeneous isotope exchange reactions analogous to those behind carbonate clumped isotope thermometry; inheritance from larger biomolecules that under thermal degradation to produce natural gas; mixing of natural gases that differ markedly in bulk isotopic composition; or combinations of these and/or other, less expected fractionations. There is little basis for predicting which of these will dominate in natural samples. Here, we focus on an analytical techniques that will provide the avenue for exploring these phenomena. The method is based on high-resolution gas source isotope ratio mass spectrometry, using the Thermo 253-Ultra (a new prototype mass spectrometer). This instrument achieves the mass resolution (M/Δ M) up to 27,000, permitting separation of the isobaric interferences of potential contaminants and isotopologues of an analtye or its fragments which share a cardinal mass. We present techniques to analyze several isotopologues of molecular and fragment ions of C2H6. The critical isobaric separations for our purposes include: discrimination of 13C2H6 from 13C12CDH5 at mass 32 and separation of the 13CH3 fragment from 12CH4 at mass 16, both requiring at least a mass resolution of 20000 to make an adequate measurement. Other obvious interferences are either cleanly separated (e.g., O2, O) or accounted for by peak-stripping (CH3OH on mass 32 and NH2 on mass 16). We focus on a set of measurements which constrain: the doubly-substituted isotopologue, 13C2H6, and the 13CH3/12CH3 ratio of the methyl fragment, which constrains the bulk δ 13C. Similar methods can be
New decay studies near the doubly-magic ^78Ni
NASA Astrophysics Data System (ADS)
Rykaczewski, Krzysztof
2008-10-01
The nucleus ^78Ni, with a closed proton shell at Z=28 and a closed neutron shell at N=50, is the most neutron-rich doubly-magic nucleus identified to date [1,2]. Spectroscopic studies of nuclei around ^78Ni are important for understading both the evolution of nuclear structure in neutron rich matter and the rapid neutron capture nucleosynthesis process. Additionaly, the beta-delayed neutron emission from neutron-rich fission products contributes to the total number of neutrons inducing fission in nuclear fuel and should be accounted for when running power reactors. The neutrons filling the large 1g9/2 shell between N=40 and N=50 impact the spin-orbit splitting of the respective proton orbital pairs, 2p3/2-2p1/2 and 1f7/2-1f5/2. This can trigger a change in the ground-state proton configuration of very neutron rich nuclei above Z=28 [3,4]. Further, the energy difference beetwen the 2d5/2 and 3s1/2 neutron orbitals above N=50 is decreasing when approaching the ^78Ni region possibly resulting in the appearance of a new subshell closure at N=58. Nuclei in the ^78Ni region are produced at the Holifield Radioactive Ion Beam Facility (HRIBF, Oak Ridge National Laboratory) by means of an on-line isotope separation technique using the fission of a ^238U target induced by a 50 MeV, 10 microAmp proton beam. The decay studies performed at the HRIBF profitted from the post-acceleration of mass-separated radioactive beams to about 200 MeV. A novel method, the so-called ranging- out technique, allowed us to separate the most neutron-rich component of the isobaric cocktail beam [5,6]. New results on the decay of A=76 to A=79 Cu isotopes and of A=83 to A=85 Ga isotopes will be presented. In particular, the measured beta-delayed neutron branching ratios for the Cu isotopes are two to four times larger than previously reported [7]. An energy of 247 keV was established for the 3s1/2 neutron state above the 2d5/2 ground- state in the N=51 isotone ^83Ge suggesting the existence of low
Production of doubly heavy-flavored hadrons at e+e- colliders
NASA Astrophysics Data System (ADS)
Zheng, Xu-Chang; Chang, Chao-Hsi; Pan, Zan
2016-02-01
Production of the doubly heavy-flavored hadrons (Bc meson, doubly heavy baryons Ξc c , Ξb c , Ξb b , their excited states, and antiparticles of them as well) at e+e- colliders is investigated under two different approaches: LO (leading-order QCD complete calculation) and LL (leading-logarithm fragmentation calculation). The results for the production obtained by the LO and LL approaches, including the angle distributions of the produced hadrons with unpolarized and polarized incoming beams, the behaviors on the energy fraction of the produced doubly heavy-flavored hadron, and comparisons of results between the two approaches, are presented in tables and figures. Thus, characteristics of the production and uncertainties of the approaches are shown precisely, and it is concluded that only if the colliders run at the energies around the Z pole (which may be called the Z factories) and the luminosity of the colliders is as high as possible is the study of the doubly heavy-flavored hadrons completely accessible.
The application of value distribution theory to a doubly anharmonic oscillator
NASA Astrophysics Data System (ADS)
Hu, Juan; Yu, Guo-Fu
2011-07-01
The model of doubly anharmonic oscillators is first transformed into certain periodic second ordinary differential equations. A class of exact solutions for eigenfunctions and eigenvalues is obtained from Bank and Laine's theory on periodic ordinary differential equations, which is expressed in the form of the products of the polynomial and exponential functions when parameters satisfy some special relations.
NASA Astrophysics Data System (ADS)
Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan
2015-01-01
This paper investigates the periodic motion of a particle in the doubly synchronous binary asteroid systems. Two typical doubly synchronous systems, 809 Lundia and 3169 Ostro, are discussed in detail. Under the Roche figure assumption, the two bodies of doubly synchronous system can be modeled as two triaxial ellipsoids. The Ivory's theorem is used to derive the gravitational potential of the system. Then, a global numerical method, which combines grid searching and differential correction, is developed for systematically searching periodic orbits in the doubly synchronous systems. A total of 30 and 28 families of periodic orbits around Lundia and Ostro are found, respectively. Furthermore, on the basis of the analysis of morphology, stabilities and invariant manifolds, the potential applications of these periodic orbit families are studied. Several quasi-circular orbit families with low instability index are found to be suitable for the observation of the two typical binary systems. The invariant manifolds of some periodic orbits near the equilibrium points can provide the fuel-free trajectories to achieve the ballistic landing to the surface of the asteroids and transfer between the binary asteroids.
Production of doubly charmed baryons at energy {radical}s=10.58 GeV
Kiselev, V.V.; Likhoded, A.K.; Shevlyagin, M.V.
1995-06-01
The cross section for the production of doubly charmed baryons at a B-factory is estimated on the basis of perturbative QCD calculations of the cross sections for cc-diquark production and of the quark-hadron duality. 14 refs., 2 figs.
Mazenko, Gene F
2008-09-01
We study the random diffusion model. This is a continuum model for a conserved scalar density field varphi driven by diffusive dynamics. The interesting feature of the dynamics is that the bare diffusion coefficient D is density dependent. In the simplest case, D=D[over ]+D_{1}deltavarphi , where D[over ] is the constant average diffusion constant. In the case where the driving effective Hamiltonian is quadratic, the model can be treated using perturbation theory in terms of the single nonlinear coupling D1 . We develop perturbation theory to fourth order in D1 . The are two ways of analyzing this perturbation theory. In one approach, developed by Kawasaki, at one-loop order one finds mode-coupling theory with an ergodic-nonergodic transition. An alternative more direct interpretation at one-loop order leads to a slowing down as the nonlinear coupling increases. Eventually one hits a critical coupling where the time decay becomes algebraic. Near this critical coupling a weak peak develops at a wave number well above the peak at q=0 associated with the conservation law. The width of this peak in Fourier space decreases with time and can be identified with a characteristic kinetic length which grows with a power law in time. For stronger coupling the system becomes metastable and then unstable. At two-loop order it is shown that the ergodic-nonergodic transition is not supported. It is demonstrated that the critical properties of the direct approach survive, going to higher order in perturbation theory.
Search for doubly charged Higgs bosons through vector boson fusion at the LHC and beyond
NASA Astrophysics Data System (ADS)
Bambhaniya, G.; Chakrabortty, J.; Gluza, J.; Jeliński, T.; Szafron, R.
2015-07-01
Production and decays of doubly charged Higgs bosons at the LHC and future hadron colliders triggered by a vector boson fusion mechanism are discussed in the context of the minimal left-right symmetric model. Our analysis is based on the Higgs boson mass spectrum compatible with available constraints which include flavor changing neutral current (FCNC) effects and vacuum stability of the scalar potential. Though the parity breaking scale vR is large (˜ few TeV) and scalar masses which contribute to FCNC effects are even larger, a consistent Higgs boson mass spectrum still allows us to keep doubly charged scalar masses below 1 TeV which is an interesting situation for LHC and future circular collider (FCC). We have shown that the allowed Higgs boson mass spectrum constrains the splittings (MH1±±-MH1± ), closing the possibility of H1±±→W1±H1± decays. Assuming that doubly charged Higgs bosons decay predominantly into a pair of same-sign charged leptons through the process p p →H1/2 ±±H1/2 ∓∓j j →ℓ±ℓ±ℓ∓ℓ∓j j , we find that for the LHC operating at √{s }=14 TeV with an integrated luminosity at the level of 3000 fb-1 (HL-LHC), there is practically no chance to detect such particles at the reasonable significance level through this channel. However, at 33 TeV HE-LHC and (or) 100 TeV FCC-hh, a wide region opens up for exploring the doubly charged Higgs boson mass spectrum. In FCC-hh, the doubly charged Higgs bosons mass up to 1 TeV can be easily probed.
NASA Astrophysics Data System (ADS)
Senoo, Y.
The influence of vaneless diffusers on flow in centrifugal compressors, particularly on surge, is discussed. A vaneless diffuser can demonstrate stable operation in a wide flow range only if it is installed with a backward leaning blade impeller. The circumferential distortion of flow in the impeller disappears quickly in the vaneless diffuser. The axial distortion of flow at the diffuser inlet does not decay easily. In large specific speed compressors, flow out of the impeller is distorted axially. Pressure recovery of diffusers at distorted inlet flow is considerably improved by half guide vanes. The best height of the vanes is a little 1/2 diffuser width. In small specific speed compressors, flow out of the impeller is not much distorted and pressure recovery can be predicted with one-dimensional flow analysis. Wall friction loss is significant in narrow diffusers. The large pressure drop at a small flow rate can cause the positive gradient of the pressure-flow rate characteristic curve, which may cause surging.
NASA Technical Reports Server (NTRS)
Fox, J. L.
1981-01-01
Models of the upper atmospheres of Mars and Venus were constructed using Viking and Pioneer Venus data. The neutral densities, with the exception of NO, N(4S), N(2D) and N(2P) were taken from the measured values, along with the neutral, ion, and electron temperatures. Using solar fluxes and relevant cross sections, the production rates of ions and neutral fragments by photo and electron impact processes were computed. These production rates were combined with chemical production rates and loss along with one dimensional transport eddy diffusion, molecular and ambi polar diffusion, and thermal diffusion, to determine the densities of ions and odd nitrogen species. Preliminary calculations show that the chemistry of metastables and doubly ionized species is important in the ionospheres of Mars and Venus. Production of N(+) in metastable reactions is particularly important, and it explains the discrepancy between the measurements of earlier models. Production of CO(+) is also affected. Reactions of O(++) and O(+)(2D) with N2 have important consequences for the escape rate of atomic nitrogen from the Martian atmosphere.
NASA Technical Reports Server (NTRS)
1981-01-01
A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.
NASA Technical Reports Server (NTRS)
Nicolet, M. A.
1983-01-01
The choice of the metallic film for the contact to a semiconductor device is discussed. One way to try to stabilize a contact is by interposing a thin film of a material that has low diffusivity for the atoms in question. This thin film application is known as a diffusion barrier. Three types of barriers can be distinguished. The stuffed barrier derives its low atomic diffusivity to impurities that concentrate along the extended defects of a polycrystalline layer. Sacrificial barriers exploit the fact that some (elemental) thin films react in a laterally uniform and reproducible fashion. Sacrificial barriers have the advantage that the point of their failure is predictable. Passive barriers are those most closely approximating an ideal barrier. The most-studied case is that of sputtered TiN films. Stuffed barriers may be viewed as passive barriers whose low diffusivity material extends along the defects of the polycrystalline host.
Diffusion of Ellipsoids in Bacterial Suspensions.
Peng, Yi; Lai, Lipeng; Tai, Yi-Shu; Zhang, Kechun; Xu, Xinliang; Cheng, Xiang
2016-02-12
Active fluids such as swarming bacteria and motile colloids exhibit exotic properties different from conventional equilibrium materials. As a peculiar example, a spherical tracer immersed inside active fluids shows an enhanced translational diffusion, orders of magnitude stronger than its intrinsic Brownian motion. Here, rather than spherical tracers, we investigate the diffusion of isolated ellipsoids in a quasi-two-dimensional bacterial bath. Our study shows a nonlinear enhancement of both translational and rotational diffusions of ellipsoids. More importantly, we uncover an anomalous coupling between particles' translation and rotation that is strictly prohibited in Brownian diffusion. The coupling reveals a counterintuitive anisotropic particle diffusion, where an ellipsoid diffuses fastest along its minor axis in its body frame. Combining experiments with theoretical modeling, we show that such an anomalous diffusive behavior arises from the generic straining flow of swimming bacteria. Our work illustrates an unexpected feature of active fluids and deepens our understanding of transport processes in microbiological systems.
Diffusion of Ellipsoids in Bacterial Suspensions
NASA Astrophysics Data System (ADS)
Peng, Yi; Lai, Lipeng; Tai, Yi-Shu; Zhang, Kechun; Xu, Xinliang; Cheng, Xiang
2016-02-01
Active fluids such as swarming bacteria and motile colloids exhibit exotic properties different from conventional equilibrium materials. As a peculiar example, a spherical tracer immersed inside active fluids shows an enhanced translational diffusion, orders of magnitude stronger than its intrinsic Brownian motion. Here, rather than spherical tracers, we investigate the diffusion of isolated ellipsoids in a quasi-two-dimensional bacterial bath. Our study shows a nonlinear enhancement of both translational and rotational diffusions of ellipsoids. More importantly, we uncover an anomalous coupling between particles' translation and rotation that is strictly prohibited in Brownian diffusion. The coupling reveals a counterintuitive anisotropic particle diffusion, where an ellipsoid diffuses fastest along its minor axis in its body frame. Combining experiments with theoretical modeling, we show that such an anomalous diffusive behavior arises from the generic straining flow of swimming bacteria. Our work illustrates an unexpected feature of active fluids and deepens our understanding of transport processes in microbiological systems.
Scaling of chaos in strongly nonlinear lattices
Mulansky, Mario
2014-06-15
Although it is now understood that chaos in complex classical systems is the foundation of thermodynamic behavior, the detailed relations between the microscopic properties of the chaotic dynamics and the macroscopic thermodynamic observations still remain mostly in the dark. In this work, we numerically analyze the probability of chaos in strongly nonlinear Hamiltonian systems and find different scaling properties depending on the nonlinear structure of the model. We argue that these different scaling laws of chaos have definite consequences for the macroscopic diffusive behavior, as chaos is the microscopic mechanism of diffusion. This is compared with previous results on chaotic diffusion [M. Mulansky and A. Pikovsky, New J. Phys. 15, 053015 (2013)], and a relation between microscopic chaos and macroscopic diffusion is established.
Minimizing radiation damage in nonlinear optical crystals
Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.
1998-09-08
Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal. 5 figs.
Minimizing radiation damage in nonlinear optical crystals
Cooke, D. Wayne; Bennett, Bryan L.; Cockroft, Nigel J.
1998-01-01
Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal.
Geometrically nonlinear analysis of layered composite plates and shells
NASA Technical Reports Server (NTRS)
Chao, W. C.; Reddy, J. N.
1983-01-01
A degenerated three dimensional finite element, based on the incremental total Lagrangian formulation of a three dimensional layered anisotropic medium was developed. Its use in the geometrically nonlinear, static and dynamic, analysis of layered composite plates and shells is demonstrated. A two dimenisonal finite element based on the Sanders shell theory with the von Karman (nonlinear) strains was developed. It is shown that the deflections obtained by the 2D shell element deviate from those obtained by the more accurate 3D element for deep shells. The 3D degenerated element can be used to model general shells that are not necessarily doubly curved. The 3D degenerated element is computationally more demanding than the 2D shell theory element for a given problem. It is found that the 3D element is an efficient element for the analysis of layered composite plates and shells undergoing large displacements and transient motion.
Nonlinear dynamics enabled systems design and control
NASA Astrophysics Data System (ADS)
Lacarbonara, Walter
2012-08-01
There is a growing interest towards design of high-performance structures and devices by seeking ways to exploit advantageously different nonlinearities at different scales rather than constraining operations to avoid nonlinear phenomena. Tools of robust nonlinear modeling and analysis are shown to be turned into design tools for achieving high levels of vibration control authority and synthesis of engineered systems and materials. A brief overview of methods and results on active resonance cancellation and passive nonlinear hysteretic vibration absorbers is illustrated. Recent results on the diffused hysteresis exhibited at the nano-microscale in nanocomposites due to the powerful nonlinear stick-slip mechanism exhibited by carbon nanotubes dispersed in a hosting matrix are discussed. The optimization of the main microstructural parameters is shown to lead to unprecedented levels of damping capacity in next-generation nanostructured materials tailored for wide-band vibrational energy dissipation.
Relativistic description of pair production of doubly heavy baryons in e{sup +}e{sup −} annihilation
Martynenko, A. P.; Trunin, A. M.
2015-05-15
Relativistic corrections in the pair production of S-wave doubly heavy diquarks in electron-positron annihilation were calculated on the basis of perturbative QCD and the quark model. The relativistic corrections to the wave functions for quark bound states were taken into account with the aid of the Breit potential in QCD. Relativistic effects change substantially the nonrelativistic cross sections for pair diquark production. The yield of pairs of (ccq) doubly heavy baryons at B factories was estimated.
Doubly Fed Induction Generator Wind Turbines with Fuzzy Controller: A Survey
Sathiyanarayanan, J. S.; Senthil Kumar, A.
2014-01-01
Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG) wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine. PMID:25028677
Sensitivity of methods for calculating energy expenditure by use of doubly labeled water
Seale, J.; Miles, C.; Bodwell, C.E.
1989-02-01
Attempts to estimate human energy expenditure by use of doubly labeled water have produced three methods currently used for calculating carbon dioxide production from isotope disappearance data: (1) the two-point method, (2) the regression method, and (3) the integration method. An ideal data set was used to determine the error produced in the calculated energy expenditure for each method when specific variables were perturbed. The analysis indicates that some of the calculation methods are more susceptible to perturbations in certain variables than others. Results from an experiment on one adult human subject are used to illustrate the potential for error in actual data. Samples of second void urine, 24-h urine, and breath collected every other day for 21 days are used to calculate the average daily energy expenditure by three calculation methods. The difference between calculated energy expenditure and metabolizable energy on a weight-maintenance diet is used to estimate the error associated with the doubly labeled water method.
Nuclear structure in the neutron-rich doubly magic sup 78 Ni region
Hill, J.C.; Wohn, F.K.; Winger, J.A.; Warburton, E.K.; Gill, R.L.; Schuhmann, R.B.; Brookhaven National Lab., Upton, NY; Clark Univ., Worcester, MA )
1989-01-01
The magic numbers Z=28 and N=50 imply that very neutron-rich {sup 78}Ni, which has not yet been observed, is doubly magic. The {sup 78}Ni region was investigated by studying the N=50 isotones and neutron-rich Zn isotopes. Results on the level structure of {sup 83}As, {sup 74}Zn, and {sup 76}Zn populated in the decays of {sup 83}Ge, {sup 74}Cu, and {sup 76}Cu are presented. The parent nuclides were produced and mass separated using the TRISTAN facility on-line to the High-Flux Beam Reactor at Brookhaven. The systematics of the N=50 isotones and even-A Zn isotopes are discussed and compared with shell-model calculations involving active nucleons outside of a {sup 78}Ni and {sup 66}Ni core, respectively. The extent to which the {sup 78}Ni region can be considered doubly magic is assessed. 43 refs., 7 figs.
Doubly fed induction generator wind turbines with fuzzy controller: a survey.
Sathiyanarayanan, J S; Kumar, A Senthil
2014-01-01
Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG) wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine. PMID:25028677
Doubly degenerate entanglement spectrum and entanglement plateau in the S=1 bond-alternating chain
NASA Astrophysics Data System (ADS)
Deng, Xiao-Yan; Dou, Jun-Ya; Liu, Guang-Hua
2015-12-01
Quantum entanglement, entanglement spectrum, magnetization, and ground-state energy of the S=1 bond-alternating antiferromagnetic Heisenberg chain under magnetic field are investigated by the infinite time-evolving block decimation (iTEBD) method. Bipartite entanglement and entanglement spectrum are found to be capable of describing all the quantum phase transitions (QPTs). A rich ground-state phase diagram, which comprises of five different phases, i.e., a singlet-dimer phase, a Haldane phase, a Tomonaga-Luttinger liquid (TLL) phase, a 1/2 plateau phase, and a saturated ferromagnetic phase, is determined. It is interesting that, with the appearance of magnetization plateaus, entanglement plateaus are observed simultaneously. In the Haldane phase, doubly degenerate entanglement spectra on both even and odd bonds are observed. However, in the 1/2 plateau phase, only the entanglement spectra on the even bonds are found to be doubly degenerated.
Synthesis of γ-Phosphate-Labeled and Doubly Labeled Adenosine Triphosphate Analogs.
Hacker, Stephan M; Welter, Moritz; Marx, Andreas
2015-03-09
This unit describes the synthesis of γ-phosphate-labeled and doubly labeled adenosine triphosphate (ATP) analogs and their characterization using the phosphodiesterase I from Crotalus adamanteus (snake venom phosphodiesterase; SVPD). In the key step of the synthesis, ATP or an ATP analog, bearing a linker containing a trifluoroacetamide group attached to the nucleoside, are modified with an azide-containing linker at the terminal phosphate using an alkylation reaction. Subsequently, different labels are introduced to the linkers by transformation of one functional group to an amine and coupling to an N-hydroxysuccinimide ester. Specifically, the Staudinger reaction of the azide is employed as a straightforward means to obtain an amine in the presence of various labels. Furthermore, the fluorescence characteristics of a fluorogenic, doubly labeled ATP analog are investigated following enzymatic cleavage by SVPD.
Doubly fed induction generator wind turbines with fuzzy controller: a survey.
Sathiyanarayanan, J S; Kumar, A Senthil
2014-01-01
Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG) wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine.
A doubly averaging method for third body perturbations in planet equator coordinates
NASA Technical Reports Server (NTRS)
Hwok, Johnny H.
1992-01-01
The first order doubly averaged potential due to third-body gravity is derived in any arbitrary coordinates. The equations of motion are nonsingular at zero eccentricity. The derivation uses a recursive method which allows easy expansion to higher order terms. Instead of using analytical quadrature to obtain the doubly averaged potential, the method presented in this paper simply eliminates the mean anomaly of the perturbed and perturbing bodies by inspection of the recursive formulation. The derivatives of the orbital elements can be numerically integrated rapidly. When a planet equator coordinate system is used, they can be added directly to the derivatives due to gravity harmonics without any coordinate transformation. The method is applied to various high altitude missions. The results are compared with a high precision numerical integration method and are found to provide excellent agreement.
Zhang, Zhiguo; Zhang, Wei; Li, Junlong; Liu, Qingfeng; Liu, Tongxin; Zhang, Guisheng
2014-11-21
An alternative route has been developed for the construction of multisubstituted pyrrole derivatives from readily available, doubly activated cyclopropanes and anilines using an iron-mediated oxidation domino reaction (i.e., sequential ring-opening, cyclization, and dehydrogenation reactions). This reaction uses readily available reactants and is tolerant of a broad range of substrates, with the desired products being formed in good to excellent yields. PMID:25330125
Mechanisms of doubly-vergent vs. single-sided orogens: insights from numerical modelling
NASA Astrophysics Data System (ADS)
Vogt, K.; Matenco, L. C.; Gerya, T.; Cloetingh, S.
2014-12-01
Zones of continent collision form mountain ranges with high topographies and complex geometries. Compressional stresses during ongoing convergence result in crustal thickening and localized deformation, where crustal material is transported and redistributed within the orogen. We use numerical high-resolution thermo-mechanical models to investigate the physical processes of continent collision zones and its implications on rock exhumation. We demonstrate that compression of two continental blocks, separated by a rheologically weak suture zone can result in (i) doubly-vergent (Fig. A) or (ii) single-sided orogens (Fig. B), with distinct geometries, deformation and exhumation patterns. The transition between these different modes of collision is strongly controlled by the rheology of the continental lithosphere and therefore its temperature distribution. Doubly-vergent orogens form at relatively high thermal gradients, while single-sided orogens are typical for lower ones. Doubly-vergent orogens (Fig. A) are formed in response to the gradual accretion of crustal material to the upper plate along retro-shears. In these models continental subduction results in upper plate deformation and nested exhumation against retro-shears. Typical examples include the collision recorded by the Swiss Alps and the Pyrenees. In contrast, single-sided orogens are characterized by large-scale lower plate deformation and are accompanied by the subduction of lower crustal material (Fig. B). Modeling infers that shortening and associated exhumation will gradually propagate towards the foreland. In this situation, no significant retro-shear formation is observed, which is in agreement with recent physical modelling studies on deformation of the continental lithosphere [Willingshofer et al., 2013]. Natural examples of such single sided orogens are common in the Mediterranean (Carpathians, Dinarides, Apennines, Betics) or the SE Asia subduction zones. We conclude that deformation and
A mathematical model for the doubly-fed wound rotor generator, part 2
NASA Technical Reports Server (NTRS)
Brady, F. J.
1984-01-01
A mathematical analysis of a doubly-fed wound rotor generator is presented. The constraints of constant stator voltage and frequency to the circuit equations were applied and expressions for the currents and voltages in the machine obtained. The derived variables are redefined as direct and quadrature components. In addition, the apparent (complex) power for both the rotor and the stator are derived in terms of these redefined components.
A mathematical model for the doubly-fed wound rotor generator. II
NASA Technical Reports Server (NTRS)
Brady, F. J.
1986-01-01
A mathematical analysis of a doubly-fed wound rotor generator is presented. The constraints of constant stator voltage and frequency to the circuit equations were applied and expressions for the currents and voltages in the machine obtained. The derived variables are redefined as direct and quadrature components. In addition, the apparent (complex) power for both the rotor and the stator are derived in terms of these redefined components.
NASA Astrophysics Data System (ADS)
Ravichandran, K.; Muruganantham, G.; Sakthivel, B.
2009-11-01
Doubly doped (simultaneous doping of antimony and fluorine) tin oxide films (SnO 2:Sb:F) have been fabricated by employing an inexpensive and simplified spray technique using perfume atomizer from aqueous solution of SnCl 2 precursor. The structural studies revealed that the films are highly crystalline in nature with preferential orientation along the (2 0 0) plane. It is found that the size of the crystallites of the doubly doped tin oxide films is larger (69 nm) than that (27 nm) of their undoped counterparts. The dislocation density of the doubly doped film is lesser (2.08×10 14 lines/m 2) when compared with that of the undoped film (13.2×10 14 lines/m 2), indicating the higher degree of crystallinity of the doubly doped films. The SEM images depict that the films are homogeneous and uniform. The optical transmittance in the visible range and the optical band gap of the doubly doped films are 71% and 3.56 eV respectively. The sheet resistance (4.13 Ω/□) attained for the doubly doped film in this study is lower than the values reported for spray deposited fluorine or antimony doped tin oxide films prepared from aqueous solution of SnCl 2 precursor (without using methanol or ethanol).
Sathiyanarayanan, Rajesh E-mail: rajesh.sathiyanarayanan@gmail.com; Pandey, R. K.; Murali, K. V. R. M.
2015-01-21
Using first-principles simulations, we have computed incorporation energies and diffusion barriers of ammonia, the nitrogen molecule and atomic nitrogen in monoclinic hafnia (m-HfO{sub 2}). Our calculations show that ammonia is likely to dissociate into an NH{sub 2} molecular unit, whereas the nitrogen molecule remains as a molecule either in the interstitial space or at an oxygen lattice site. The lowest energy pathway for the diffusion of atomic nitrogen interstitials consists of the hopping of the nitrogen interstitial between neighboring three-coordinated lattice oxygen atoms that share a single Hf atom, and the barrier for such hops is determined by a switching mechanism. The substitutional nitrogen atom shows a preference for diffusion through the doubly positive oxygen vacancy-mediated mechanism. Furthermore, we have investigated the impact of nitrogen atoms on the diffusion barriers of oxygen and hydrogen interstitials in m-HfO{sub 2}. Our results show that nitrogen incorporation has a significant impact on the barriers for oxygen and hydrogen diffusion: nitrogen atoms attract oxygen and hydrogen interstitials diffusing in the vicinity, thereby slowing down (reducing) their diffusion (diffusion length)
Evaluation of a doubly-swept blade tip for rotorcraft noise reduction
NASA Technical Reports Server (NTRS)
Wake, Brian E.; Egolf, T. Alan
1992-01-01
A computational study was performed for a doubly-swept rotor blade tip to determine its benefit for high-speed impulsive (HSI) and blade-vortex interaction (BVI) noise. This design consists of aft and forward sweep. For the HSI-noise computations, unsteady Euler calculations were performed for several variations to a rotor blade geometry. A doubly-swept planform was predicted to increase the delocalizing Mach number to 0.94 (representative of a 200+ kt helicopter). For the BVI-noise problem, it had been hypothesized that the doubly-swept blade tip, by producing a leading-edge vortex, would reduce the tip-vortex effect on BVI noise. A procedure was used in which the tip vortex velocity profile computed by a Navier-Stokes solver was used to compute the inflow associated with BVI. This inflow was used by a Euler solver to compute the unsteady pressures for an acoustic analysis. The results of this study were inconclusive due to the difficulty in accurately predicting the viscous tip vortex downstream of the blade. Also, for the condition studied, no leading-edge vortex formed at the tip.
Use of the doubly labeled water technique in humans during heavy sustained exercise
Westerterp, K.R.; Saris, W.H.; van Es, M.; ten Hoor, F.
1986-12-01
We measured energy expenditure with the doubly labeled water technique during heavy sustained exercise in the Tour de France, a bicycle race lasting more than 3 wk. Four subjects were observed for consecutive intervals of 7, 8, and 7 days. Each interval started with an oral isotope dose to reach an excess isotope level of 200 ppm 18O and 130 ppm 2H. The biological half-lives of the isotopes were between 2.25 and 3.80 days. Energy expenditure was compared with simultaneous measurements of energy intake, and body mass and body composition did not change significantly. The doubly labeled water technique gave higher values for energy expenditure than the food record technique. The discrepancy showed a systematic increment from the first to the third interval, being 12.9 +/- 7.9, 21.4 +/- 9.8, and 35.3 +/- 4.4% of the energy expenditure calculated from dietary intake, respectively. Possible explanations for the discrepancy are discussed. The subjects reached an average daily metabolic rate of 3.4-3.9 or 4.3-5.3 times basal metabolic rate based on the food record technique and the doubly labeled water technique, respectively. Thus, when measured with the same technique, the energetic ceiling for performance in humans is comparable with that of animals like birds.
A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - II. Verifications
Choi, Sooyoung; Kong, Chidong; Lee, Deokjung; Williams, Mark L.
2015-03-09
A new methodology has been developed recently to treat resonance self-shielding in systems for which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. The theoretical development adopts equivalence theory in both micro- and macro-level heterogeneities to provide approximate analytical expressions for the shielded cross sections, which may be interpolated from a table of resonance integrals or Bondarenko factors using a modified background cross section as the interpolation parameter. This paper describes the first implementation of the theoretical equations in a reactor analysis code. In order to reduce discrepancies caused bymore » use of the rational approximation for collision probabilities in the original derivation, a new formulation for a doubly heterogeneous Bell factor is developed in this paper to improve the accuracy of doubly heterogeneous expressions. This methodology is applied to a wide range of pin cell and assembly test problems with varying geometry parameters, material compositions, and temperatures, and the results are compared with continuous-energy Monte Carlo simulations to establish the accuracy and range of applicability of the new approach. It is shown that the new doubly heterogeneous self-shielding method including the Bell factor correction gives good agreement with reference Monte Carlo results.« less
Metastable dissociation of doubly charged CO/sub 2/ cluster ions
Leiter, K.; Kreisle, D.; Echt, O.; Maerk, T.D.
1987-05-07
Multiply charged CO/sub 2/ cluster ions are produced by adiabatic nozzle expansion and subsequent ionization by electron impact. They are analyzed in a double focussing sector field mass spectrometer (reversed geometry). (CO/sub 2/)/sub n//sup 2 +/ cluster ions are only detected above an electron energy of about 30 eV and with sizes n greater than or equal to 45 in the direct mass spectrum. Metastable decay reactions of these ions occurring in the first field free region are investigated by decoupling the analyzer fields. It is shown that (CO/sub 2/)/sub n//sub 2//sup +/ with sizes of n greater than or equal to 44 lose one neutral monomer or, roughly ten times less probable, two neutral monomers in these dissociation reactions. The total effective dissociation rates for these dissociation processes are very large, e.g. approx.2 x 10/sup 4/ s/sup -1/ for (CO/sub 2/)/sub 47//sup 2 +/. Conversely, no singly charged fragment ions were observed to be produced by Coulomb explosion from doubly charged clusters in the first field free region. Moreover, besides doubly charged stoichiometric ions the existence of doubly charged fragment cluster ions with n greater than or equal to 44 in observed in the mass spectra.
Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei
NASA Astrophysics Data System (ADS)
Leoni, S.
2016-05-01
The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets), with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic "hybrid" model is introduced: it is based on the coupling between core excitations (both collective and non-collective) of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.
Swaney, Danielle L; McAlister, Graeme C; Wirtala, Matthew; Schwartz, Jae C; Syka, John E P; Coon, Joshua J
2007-01-15
Electron-transfer dissociation (ETD) delivers the unique attributes of electron capture dissociation to mass spectrometers that utilize radio frequency trapping-type devices (e.g., quadrupole ion traps). The method has generated significant interest because of its compatibility with chromatography and its ability to: (1) preserve traditionally labile post-translational modifications (PTMs) and (2) randomly cleave the backbone bonds of highly charged peptide and protein precursor ions. ETD, however, has shown limited applicability to doubly protonated peptide precursors, [M + 2H]2+, the charge and type of peptide most frequently encountered in "bottom-up" proteomics. Here we describe a supplemental collisional activation (CAD) method that targets the nondissociated (intact) electron-transfer (ET) product species ([M + 2H]+*) to improve ETD efficiency for doubly protonated peptides (ETcaD). A systematic study of supplementary activation conditions revealed that low-energy CAD of the ET product population leads to the near-exclusive generation of c- and z-type fragment ions with relatively high efficiency (77 +/- 8%). Compared to those formed directly via ETD, the fragment ions were found to comprise increased relative amounts of the odd-electron c-type ions (c+*) and the even-electron z-type ions (z+). A large-scale analysis of 755 doubly charged tryptic peptides was conducted to compare the method (ETcaD) to ion trap CAD and ETD. ETcaD produced a median sequence coverage of 89%-a significant improvement over ETD (63%) and ion trap CAD (77%).
A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - II. Verifications
Choi, Sooyoung; Kong, Chidong; Lee, Deokjung; Williams, Mark L.
2015-03-09
A new methodology has been developed recently to treat resonance self-shielding in systems for which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. The theoretical development adopts equivalence theory in both micro- and macro-level heterogeneities to provide approximate analytical expressions for the shielded cross sections, which may be interpolated from a table of resonance integrals or Bondarenko factors using a modified background cross section as the interpolation parameter. This paper describes the first implementation of the theoretical equations in a reactor analysis code. In order to reduce discrepancies caused by use of the rational approximation for collision probabilities in the original derivation, a new formulation for a doubly heterogeneous Bell factor is developed in this paper to improve the accuracy of doubly heterogeneous expressions. This methodology is applied to a wide range of pin cell and assembly test problems with varying geometry parameters, material compositions, and temperatures, and the results are compared with continuous-energy Monte Carlo simulations to establish the accuracy and range of applicability of the new approach. It is shown that the new doubly heterogeneous self-shielding method including the Bell factor correction gives good agreement with reference Monte Carlo results.
Doubly excited states of ammonia by scattered electron-ion coincidence measurements
NASA Astrophysics Data System (ADS)
Yamamoto, Karin; Sakai, Yasuhiro
2012-03-01
To obtain information on the optically forbidden doubly excited states of ammonia (NH3), we performed scattered electron-ion coincidence measurements. First, we observed scattered electrons using electron energy-loss spectroscopy and determined the generalized oscillator strength distribution (GOSD) under 200 eV incident electron energy at a scattering angle of 8°. Ionic GOSDs were also determined by combination with the coincidence signal, which was observed by the time-of-flight mass spectrometer at each energy-loss value, for each ion. The total and partial ionic GOSDs were compared with the experimental results of both photon and fast electron impact. Moreover, the neutral GOSD determined by subtracting the total ionic GOSD from the total was compared with previous results. In addition to the optically forbidden doubly excited states, which were identified by Kato et al (2003 J. Phys. B: At. Mol. Opt. Phys. 36 3541) and Ishikawa et al (2008 J. Phys. B: At. Mol. Opt. Phys. 41 195204), we found a new optically forbidden doubly excited state at around 35 eV.
Evaluation of a doubly-swept blade tip for rotorcraft noise reduction
NASA Astrophysics Data System (ADS)
Wake, Brian E.; Egolf, T. Alan
1992-10-01
A computational study was performed for a doubly-swept rotor blade tip to determine its benefit for high-speed impulsive (HSI) and blade-vortex interaction (BVI) noise. This design consists of aft and forward sweep. For the HSI-noise computations, unsteady Euler calculations were performed for several variations to a rotor blade geometry. A doubly-swept planform was predicted to increase the delocalizing Mach number to 0.94 (representative of a 200+ kt helicopter). For the BVI-noise problem, it had been hypothesized that the doubly-swept blade tip, by producing a leading-edge vortex, would reduce the tip-vortex effect on BVI noise. A procedure was used in which the tip vortex velocity profile computed by a Navier-Stokes solver was used to compute the inflow associated with BVI. This inflow was used by a Euler solver to compute the unsteady pressures for an acoustic analysis. The results of this study were inconclusive due to the difficulty in accurately predicting the viscous tip vortex downstream of the blade. Also, for the condition studied, no leading-edge vortex formed at the tip.
NASA Technical Reports Server (NTRS)
1976-01-01
The development of two new shell finite elements for applications to large deflection problems is considered. The elements in question are doubly curved and of triangular and quadrilateral planform. They are restricted to small strains of elastic materials, and can accommodate large rotations. The elements described, which are based on relatively simple linear elements, make use of a new displacement function approach specifically designed for strongly nonlinear problems. The displacement function development for nonlinear applications is based on certain beam element formulations, and the strain-displacement equations are of a shallow shell type. Additional terms were included in these equations in an attempt to avoid the large errors characteristic of shallow shell elements in certain types of problems. An incremental nonlinear solution procedure specifically adopted to the element formulation was developed. The solution procedure is of combined incremental and total Lagrangian type, and uses a new updating scheme. A computer program was written to evaluate the developed formulations. This program can accommodate small element groups in arbitrary arrangements. Two simple programs were successfully solved. The results indicate that this new type of element has definite promise and should be a fruitful area for further research.
Nonlinear parallel momentum transport in strong electrostatic turbulence
NASA Astrophysics Data System (ADS)
Wang, Lu; Wen, Tiliang; Diamond, P. H.
2015-05-01
Most existing theoretical studies of momentum transport focus on calculating the Reynolds stress based on quasilinear theory, without considering the nonlinear momentum flux- ⟨ v ˜ r n ˜ u ˜ ∥ ⟩ . However, a recent experiment on TORPEX found that the nonlinear toroidal momentum flux induced by blobs makes a significant contribution as compared to the Reynolds stress [Labit et al., Phys. Plasmas 18, 032308 (2011)]. In this work, the nonlinear parallel momentum flux in strong electrostatic turbulence is calculated by using a three dimensional Hasegawa-Mima equation, which is relevant for tokamak edge turbulence. It is shown that the nonlinear diffusivity is smaller than the quasilinear diffusivity from Reynolds stress. However, the leading order nonlinear residual stress can be comparable to the quasilinear residual stress, and so may be important to intrinsic rotation in tokamak edge plasmas. A key difference from the quasilinear residual stress is that parallel fluctuation spectrum asymmetry is not required for nonlinear residual stress.
ERIC Educational Resources Information Center
Foy, Barry G.
1977-01-01
Two demonstrations are described. Materials and instructions for demonstrating movement of molecules into cytoplasm using agar blocks, phenolphthalein, and sodium hydroxide are given. A simple method for demonstrating that the rate of diffusion of a gas is inversely proportional to its molecular weight is also presented. (AJ)
NASA Astrophysics Data System (ADS)
Haba, Z.
2009-02-01
We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.
ERIC Educational Resources Information Center
Dou, Remy; Hogan, DaNel; Kossover, Mark; Spuck, Timothy; Young, Sarah
2013-01-01
Diffusion has often been taught in science courses as one of the primary ways by which molecules travel, particularly within organisms. For years, classroom teachers have used the same common demonstrations to illustrate this concept (e.g., placing drops of food coloring in a beaker of water). Most of the time, the main contributor to the motion…
Haba, Z
2009-02-01
We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.
Diffusion, Viscosity and Crystal Growth in Microgravity
NASA Technical Reports Server (NTRS)
Myerson, Allan S.
1996-01-01
The diffusivity of TriGlycine Sulfate (TGS), Potassium Dihydrogen Phosphate (KDP), Ammonium Dihydrogen Phosphate (ADF) and other compounds of interest to microgravity crystal growth, in supersaturated solutions as a function of solution concentration, 'age' and 'history was studied experimentally. The factors that affect the growth of crystals from water solutions in microgravity have been examined. Three non-linear optical materials have been studied, potassium dihydrogen phosphate (KDP), ammonium dihydrogen phosphate (ADP) and triglycine sulfate (TGC). The diffusion coefficient and viscosity of supersaturated water solutions were measured. Also theoretical model of diffusivity and viscosity in a metastable state, model of crystal growth from solution including non-linear time dependent diffusivity and viscosity effect and computer simulation of the crystal growth process which allows simulation of the microgravity crystal growth were developed.
New Nonlinear Multigrid Analysis
NASA Technical Reports Server (NTRS)
Xie, Dexuan
1996-01-01
The nonlinear multigrid is an efficient algorithm for solving the system of nonlinear equations arising from the numerical discretization of nonlinear elliptic boundary problems. In this paper, we present a new nonlinear multigrid analysis as an extension of the linear multigrid theory presented by Bramble. In particular, we prove the convergence of the nonlinear V-cycle method for a class of mildly nonlinear second order elliptic boundary value problems which do not have full elliptic regularity.
Diffusion Simulation and Lifetime Calculation at RHIC
Abreu,N.P.; Fischer, W.; Luo, Y.; Robert-Demolaize, G.
2009-01-02
The beam lifetime is an important parameter for any storage ring. For protons in RHIC it is dominated by the non-linear nature of the head-on collisions that causes the particles to diffuse outside the stable area in phase space. In this report we show results from diffusion simulation and lifetime calculation for the 2006 and 2008 polarized proton runs in RHIC.
Anomalous diffusion in silo drainage.
Arévalo, R; Garcimartín, A; Maza, D
2007-06-01
The silo discharge process is studied by molecular dynamics simulations. The development of the velocity profile and the probability density function for the displacements in the horizontal and vertical axis are obtained. The PDFs obtained at the beginning of the discharge reveal non-Gaussian statistics and superdiffusive behaviors. When the stationary flow is developed, the PDFs at shorter temporal scales are non-Gaussian too. For big orifices a well-defined transition between ballistic and diffusive regime is observed. In the case of a small outlet orifice, no well-defined transition is observed. We use a nonlinear diffusion equation introduced in the framework of non-extensive thermodynamics in order to describe the movements of the grains. The solution of this equation gives a well-defined relationship (gamma = 2/(3 - q)) between the anomalous diffusion exponent gamma and the entropic parameter q introduced by the non-extensive formalism to fit the PDF of the fluctuations.
Diffusion of finite-size particles in confined geometries.
Bruna, Maria; Chapman, S Jonathan
2014-04-01
The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle's dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion that depends on both the excluded-volume and the narrow confinement. By including both these effects, the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined.
[Nonlinear magnetohydrodynamics
Not Available
1994-01-01
Resistive MHD equilibrium, even for small resistivity, differs greatly from ideal equilibrium, as do the dynamical consequences of its instabilities. The requirement, imposed by Faraday`s law, that time independent magnetic fields imply curl-free electric fields, greatly restricts the electric fields allowed inside a finite-resistivity plasma. If there is no flow and the implications of the Ohm`s law are taken into account (and they need not be, for ideal equilibria), the electric field must equal the resistivity times the current density. The vanishing of the divergence of the current density then provides a partial differential equation which, together with boundary conditions, uniquely determines the scalar potential, the electric field, and the current density, for any given resistivity profile. The situation parallels closely that of driven shear flows in hydrodynamics, in that while dissipative steady states are somewhat more complex than ideal ones, there are vastly fewer of them to consider. Seen in this light, the vast majority of ideal MHD equilibria are just irrelevant, incapable of being set up in the first place. The steady state whose stability thresholds and nonlinear behavior needs to be investigated ceases to be an arbitrary ad hoc exercise dependent upon the whim of the investigator, but is determined by boundary conditions and choice of resistivity profile.
Photorefractive surface nonlinearly chirped waveguide arrays
NASA Astrophysics Data System (ADS)
Qi, Pengfei; Feng, Tianrun; Wang, Sainan; Han, Rong; Hu, Zhijian; Zhang, Tianhao; Tian, Jianguo; Xu, Jingjun
2016-05-01
We report an alternate type of nonlinear waveguides, photorefractive surface nonlinearly chirped waveguide arrays, which can be directly induced by photorefractive surface waves in virtue of diffusion and drift nonlinearities. The amplitude of such nonlinearly chirped waveguide arrays has an apodized envelope owing to the diffusion nonlinearity. The refractive-index change of the apodized tails converges to a nonzero value which can be handily adjusted by an external electric field. Moreover, the chirp parameters such as amplitude, sign (positive or negative), and initial position can be conveniently adjusted by an external electric field, background illumination, incident beam, etc. Then the guided-wave properties of this type of waveguide arrays are analyzed by using the transfer matrix method. Owing to the flexible tail and the nonlinear chirp, the dispersion curves of the index-guided modes can be tailored by an external electric field and the dispersion curves of ordinary and extraordinary Bragg guided modes couple, intertwine, and anticross with each other. Meanwhile, there is a clear "competition" in the coupling hybrid mode near anticrossing.
Anderson, Robert C.
1976-06-22
1. A method for joining beryllium to beryllium by diffusion bonding, comprising the steps of coating at least one surface portion of at least two beryllium pieces with nickel, positioning a coated surface portion in a contiguous relationship with an other surface portion, subjecting the contiguously disposed surface portions to an environment having an atmosphere at a pressure lower than ambient pressure, applying a force upon the beryllium pieces for causing the contiguous surface portions to abut against each other, heating the contiguous surface portions to a maximum temperature less than the melting temperature of the beryllium, substantially uniformly decreasing the applied force while increasing the temperature after attaining a temperature substantially above room temperature, and maintaining a portion of the applied force at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions.
Rawson, P. D.; Secor, C. L.; Hilbish, T. J.
1996-01-01
Blue mussels in the Mytilus edulis species complex have a doubly uniparental mode of mtDNA inheritance with separate maternal and paternal mtDNA lineages. Female mussels inherit their mtDNA solely from their mother, while males inherit mtDNA from both parents. In the male gonad the paternal mtDNA is preferentially replicated so that only paternal mtDNA is transmitted from fathers to sons. Hybridization is common among differentiated blue mussel taxa; whenever it involves M. trossulus, doubly uniparental mtDNA inheritance is disrupted. We have found high frequencies of males without and females with paternal mtDNA among hybrid mussels produced by interspecific matings between M. galloprovincialis and M. trossulus. In contrast, hybridization between M. galloprovincialis and M. edulis does not affect doubly uniparental inheritance, indicating a difference in the divergence of the mechanisms regulating mtDNA inheritance among the three blue mussel taxa. Our data indicate a high frequency of disrupted mtDNA transmission in F(1) hybrids and suggest that two separate mechanisms, one regulating the transmission of paternal mtDNA to males and another inhibiting the establishment of paternal mtDNA in females, act to regulate doubly uniparental inheritance. We propose a model for the regulation of doubly uniparental inheritance that is consistent with these observations. PMID:8878689
Experimental verification of a bridge-shaped, nonlinear vibration energy harvester
Gafforelli, Giacomo Corigliano, Alberto; Xu, Ruize; Kim, Sang-Gook
2014-11-17
This paper reports a comprehensive modeling and experimental characterization of a bridge shaped nonlinear energy harvester. A doubly clamped beam at large deflection requires stretching strain in addition to the bending strain to be geometrically compatible, which stiffens the beam as the beam deflects and transforms the dynamics to a nonlinear regime. The Duffing mode non-linear resonance widens the frequency bandwidth significantly at higher frequencies than the linear resonant frequency. The modeling includes a nonlinear measure of strain coupled with piezoelectric constitutive equations which end up in nonlinear coupling terms in the equations of motion. The main result supports that the power generation is bounded by the mechanical damping for both linear and nonlinear harvesters. Modeling also shows the power generation is over a wider bandwidth in the nonlinear case. A prototype is manufactured and tested to measure the power generation at different load resistances and acceleration amplitudes. The prototype shows a nonlinear behavior with well-matched experimental data to the modeling.
A multigrid Newton-Krylov method for flux-limited radiation diffusion
Rider, W.J.; Knoll, D.A.; Olson, G.L.
1998-09-01
The authors focus on the integration of radiation diffusion including flux-limited diffusion coefficients. The nonlinear integration is accomplished with a Newton-Krylov method preconditioned with a multigrid Picard linearization of the governing equations. They investigate the efficiency of the linear and nonlinear iterative techniques.
NASA Astrophysics Data System (ADS)
Ren, Jianhua; Tian, Yuan; Hossain, Ekram; Connolly, Michael D.
2016-04-01
Peptoids are peptide-mimicking oligomers consisting of N-alkylated glycine units. The fragmentation patterns for six singly and doubly protonated model peptoids were studied via collision-induced dissociation tandem mass spectrometry. The experiments were carried out on a triple quadrupole mass spectrometer with an electrospray ionization source. Both singly and doubly protonated peptoids were found to fragment mainly at the backbone amide bonds to produce peptoid B-type N-terminal fragment ions and Y-type C-terminal fragment ions. However, the relative abundances of B- versus Y-ions were significantly different. The singly protonated peptoids fragmented by producing highly abundant Y-ions and lesser abundant B-ions. The Y-ion formation mechanism was studied through calculating the energetics of truncated peptoid fragment ions using density functional theory and by controlled experiments. The results indicated that Y-ions were likely formed by transferring a proton from the C-H bond of the N-terminal fragments to the secondary amine of the C-terminal fragments. This proton transfer is energetically favored, and is in accord with the observation of abundant Y-ions. The calculations also indicated that doubly protonated peptoids would fragment at an amide bond close to the N-terminus to yield a high abundance of low-mass B-ions and high-mass Y-ions. The results of this study provide further understanding of the mechanisms of peptoid fragmentation and, therefore, are a valuable guide for de novo sequencing of peptoid libraries synthesized via combinatorial chemistry.
Doubly ionic hydrogen bond interactions within the choline chloride-urea deep eutectic solvent.
Ashworth, Claire R; Matthews, Richard P; Welton, Tom; Hunt, Patricia A
2016-07-21
Deep eutectic solvents (DESs) are exemplars of systems with the ability to form neutral, ionic and doubly ionic H-bonds. Herein, the pairwise interactions of the constituent components of the choline chloride-urea DES are examined. Evidence is found for a tripodal CHCl doubly ionic H-bond motif. Moreover it is found that the covalency of doubly ionic H-bonds can be greater than, or comparable with, neutral and ionic examples. In contrast to many traditional solvents, an "alphabet soup" of many different types of H-bond (OHO[double bond, length as m-dash]C, NHO[double bond, length as m-dash]C, OHCl, NHCl, OHNH, CHCl, CHO[double bond, length as m-dash]C, NHOH and NHNH) can form. These H-bonds exhibit substantial flexibility in terms of number and strength. It is anticipated that H-bonding will have a significant impact on the entropy of the system and thus could play an important role in the formation of the eutectic. The 2 : 1 urea : choline-chloride eutectic point of this DES is often associated with the formation of a [Cl(urea)2](-) complexed anion. However, urea is found to form a H-bonded urea[choline](+) complexed cation that is energetically competitive with [Cl(urea)2](-). The negative charge on [Cl(urea)2](-) is found to remain localised on the chloride, moreover, the urea[choline](+) complexed cation forms the strongest H-bond studied here. Thus, there is potential to consider a urea[choline](+)·urea[Cl](-) interaction. PMID:27328990
Doubly ionic hydrogen bond interactions within the choline chloride-urea deep eutectic solvent.
Ashworth, Claire R; Matthews, Richard P; Welton, Tom; Hunt, Patricia A
2016-07-21
Deep eutectic solvents (DESs) are exemplars of systems with the ability to form neutral, ionic and doubly ionic H-bonds. Herein, the pairwise interactions of the constituent components of the choline chloride-urea DES are examined. Evidence is found for a tripodal CHCl doubly ionic H-bond motif. Moreover it is found that the covalency of doubly ionic H-bonds can be greater than, or comparable with, neutral and ionic examples. In contrast to many traditional solvents, an "alphabet soup" of many different types of H-bond (OHO[double bond, length as m-dash]C, NHO[double bond, length as m-dash]C, OHCl, NHCl, OHNH, CHCl, CHO[double bond, length as m-dash]C, NHOH and NHNH) can form. These H-bonds exhibit substantial flexibility in terms of number and strength. It is anticipated that H-bonding will have a significant impact on the entropy of the system and thus could play an important role in the formation of the eutectic. The 2 : 1 urea : choline-chloride eutectic point of this DES is often associated with the formation of a [Cl(urea)2](-) complexed anion. However, urea is found to form a H-bonded urea[choline](+) complexed cation that is energetically competitive with [Cl(urea)2](-). The negative charge on [Cl(urea)2](-) is found to remain localised on the chloride, moreover, the urea[choline](+) complexed cation forms the strongest H-bond studied here. Thus, there is potential to consider a urea[choline](+)·urea[Cl](-) interaction.
Mass Spectrometric Observation of Doubly Charged Alkaline-Earth Argon Ions.
Hattendorf, Bodo; Gusmini, Bianca; Dorta, Ladina; Houk, Robert S; Günther, Detlef
2016-09-01
Doubly charged diatomic ions MAr(2+) where M=Mg, Ca, Sr or Ba have been observed by mass spectrometry with an inductively coupled plasma ion source. Abundance ratios are quite high, 0.1 % for MgAr(2+) , 0.4 % for CaAr(2+) , 0.2 % for SrAr(2+) and 0.1 % for BaAr(2+) relative to the corresponding doubly charged atomic ions M(2+) . It is assumed that these molecular ions are formed through reactions of the doubly charged metal ions with neutral argon atoms within the ion source. Bond dissociation energies (D0 ) were calculated and agree well with previously published values. The abundance ratios MAr(+) /M(+) and MAr(2+) /M(2+) generally follow the predicted bond dissociation energies with the exception of MgAr(2+) . Mg(2+) should form the strongest bond with Ar [D0 (MgAr(2+) )=124 to 130 kJ mol(-1) ] but its relative abundance is similar to that of the weakest bound BaAr(2+) (D0 =34 to 42 kJ mol(-1) ). The relative abundances of the various MAr(2+) ions are higher than those expected from an argon plasma at T=6000 K, indicating that collisions during ion extraction reduce the abundance of the MAr(2+) ions relative to the composition in the source. The corresponding singly charged MAr(+) ions are also observed but occur at about three orders of magnitude lower intensity than MAr(2+) . PMID:27252087
Nonlinear Chemical Dynamics and Synchronization
NASA Astrophysics Data System (ADS)
Li, Ning
Alan Turing's work on morphogenesis, more than half a century ago, continues to motivate and inspire theoretical and experimental biologists even today. That said, there are very few experimental systems for which Turing's theory is applicable. In this thesis we present an experimental reaction-diffusion system ideally suited for testing Turing's ideas in synthetic "cells" consisting of microfluidically produced surfactant-stabilized emulsions in which droplets containing the Belousov-Zhabotinsky (BZ) oscillatory chemical reactants are dispersed in oil. The BZ reaction has become the prototype of nonlinear dynamics in chemistry and a preferred system for exploring the behavior of coupled nonlinear oscillators. Our system consists of a surfactant stabilized monodisperse emulsion of drops of aqueous BZ solution dispersed in a continuous phase of oil. In contrast to biology, here the chemistry is understood, rate constants are measured and interdrop coupling is purely diffusive. We explore a large set of parameters through control of rate constants, drop size, spacing, and spatial arrangement of the drops in lines and rings in one-dimension (1D) and hexagonal arrays in two-dimensions (2D). The Turing model is regarded as a metaphor for morphogenesis in biology but not for prediction. Here, we develop a quantitative and falsifiable reaction-diffusion model that we experimentally test with synthetic cells. We quantitatively establish the extent to which the Turing model in 1D describes both stationary pattern formation and temporal synchronization of chemical oscillators via reaction-diffusion and in 2D demonstrate that chemical morphogenesis drives physical differentiation in synthetic cells.
Levenson, L.
1963-09-01
A high-vacuum diffusion pump is described, featuring a novel housing geometry for enhancing pumping speed. An upright, cylindrical lower housing portion is surmounted by a concentric, upright, cylindrical upper housing portion of substantially larger diameter; an uppermost nozzle, disposed concentrically within the upper portion, is adapted to eject downwardly a conical sheet of liquid outwardly to impinge upon the uppermost extremity of the interior wall of the lower portion. Preferably this nozzle is mounted upon a pedestal rising coaxially from within the lower portion and projecting up into said upper portion. (AEC)
Vantournhout, Klaas; Jachowicz, Natalie; Ryckebusch, Jan
2011-09-15
We present a method that offers perspectives to perform fully antisymmetrized simulations for inhomogeneous bulk fermion matter. The technique bears resemblance to classical periodic boundary conditions, using localized single-particle states. Such localized states are an ideal tool to discuss phenomena where spatial localization plays an important role. The antisymmetrization is obtained introducing a doubly periodic structure in the many-body fermion wave functions. This results in circulant matrices for the evaluation of expectation values, leading to a computationally tractable formalism to study fully antisymmetrized bulk fermion matter. We show that the proposed technique is able to reproduce essential fermion features in an elegant and computationally advantageous manner.
NASA Astrophysics Data System (ADS)
Venkateshwarlu, D.; Shanmukhrao, S.; Pandya, Swati; Chandra, L. S. Sharath; Vishwakarma, P. N.; Jain, Deepti; Gangrade, Mohan; Ganesan, V.
2011-07-01
Skutterudites is known to have fascinating ground states depending upon the void filling. Heat capacity of partially filled Pr0.8Pt4Ge12 and doubly filled Pr0.8Nd0.2Pt4Ge12 skutterudites has been investigated. Superconducting gaps have been quantified through heat capacity in the presence of magnetic fields. C/T versus T2 plot of Pr0.8Nd0.2Pt4Ge12 shows an upturn at low temperatures and this tendency increases with magnetic field, suggesting the possibility of a field induced NFL like states due to magnetic correlations co-existing with superconductivity.
Zhang, Ying; Xu, Xin; Goddard, William A.
2009-01-01
We develop and validate a density functional, XYG3, based on the adiabatic connection formalism and the Görling–Levy coupling-constant perturbation expansion to the second order (PT2). XYG3 is a doubly hybrid functional, containing 3 mixing parameters. It has a nonlocal orbital-dependent component in the exchange term (exact exchange) plus information about the unoccupied Kohn–Sham orbitals in the correlation part (PT2 double excitation). XYG3 is remarkably accurate for thermochemistry, reaction barrier heights, and nonbond interactions of main group molecules. In addition, the accuracy remains nearly constant with system size. PMID:19276116
Classification of doubly wound nucleotide binding topologies using automated loop searches.
Swindells, M. B.
1993-01-01
A classification is presented of doubly wound alpha/beta nucleotide binding topologies, whose binding sites are located in the cleft formed by a topological switch point. In particular, the switch point loop nearest the N-terminus is used to identify specific structural classes of binding protein. This yields seven structurally distinct loop conformations, which are subsequently used as motifs for scanning the Protein Data Bank. The searches, which are effective at identifying functional relationships within a large database of structures, reveal a remarkable and previously unnoticed similarity between the coenzyme binding sites of flavodoxin and tryptophan synthetase, even though there is no sequence or topological similarity between them. PMID:8298462
Ultrafast spectroscopy of super high frequency mechanical modes of doubly clamped beams
NASA Astrophysics Data System (ADS)
Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Grebing, Jochen; Erbe, Artur; Mounier, Denis; Gusev, Vitalyi; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S.
2013-12-01
We use ultrafast pump-probe spectroscopy to study the mechanical vibrations in the time domain of doubly clamped silicon nitride beams. Beams with two different clamping conditions are investigated. Finite element method calculations are performed to analyse the mode spectra of both structures. By calculating the strain integral on the surface of the resonators, we are able to reproduce the effect of the detection mechanism and identify all the measured modes. We show that our spectroscopy technique combined with our modelling tools allow the investigation of several different modes in the super high frequency range (3-30 GHz) and above, bringing more information about the vibration modes of nanomechanical resonators.
Doubly stochastic Poisson process models for precipitation at fine time-scales
NASA Astrophysics Data System (ADS)
Ramesh, Nadarajah I.; Onof, Christian; Xie, Dichao
2012-09-01
This paper considers a class of stochastic point process models, based on doubly stochastic Poisson processes, in the modelling of rainfall. We examine the application of this class of models, a neglected alternative to the widely-known Poisson cluster models, in the analysis of fine time-scale rainfall intensity. These models are mainly used to analyse tipping-bucket raingauge data from a single site but an extension to multiple sites is illustrated which reveals the potential of this class of models to study the temporal and spatial variability of precipitation at fine time-scales.
Power enhancement of burst-mode UV pulses using a doubly-resonant optical cavity
Rahkman, Abdurahim; Notcutt, Mark; Liu, Yun
2015-11-24
We report a doubly-resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (IR, 1064 nm) and its frequency tripled ultraviolet (UV, 355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber optic frequency shifter. The DREC technique opens a new paradigm in the applications of optical cavities to power enhancement of burst-mode lasers with arbitrary macropulse width and repetition rate.
NASA Astrophysics Data System (ADS)
Zhang, Jianzhong; Wang, Minxi; Cheng, Ming
2012-04-01
Iron losses in doubly salient permanent magnet (DSPM) machine are difficult to predict, as the flux waveforms are complex and dc bias existed. This paper measures iron losses at no load for different rotor speeds and these measured loss data are used to calibrate the iron loss model of the DSPM machine. Then the iron losses at rated load are predicted under three phase rectangular currents exerting on the armature windings. The result shows that small increment of iron losses is in the rotor at rated load which do benefit to the rotor thermal dissipation design.
One-neutron removal measurement reveals 24O as a new doubly magic nucleus.
Kanungo, R; Nociforo, C; Prochazka, A; Aumann, T; Boutin, D; Cortina-Gil, D; Davids, B; Diakaki, M; Farinon, F; Geissel, H; Gernhäuser, R; Gerl, J; Janik, R; Jonson, B; Kindler, B; Knöbel, R; Krücken, R; Lantz, M; Lenske, H; Litvinov, Y; Lommel, B; Mahata, K; Maierbeck, P; Musumarra, A; Nilsson, T; Otsuka, T; Perro, C; Scheidenberger, C; Sitar, B; Strmen, P; Sun, B; Szarka, I; Tanihata, I; Utsuno, Y; Weick, H; Winkler, M
2009-04-17
The first measurement of the momentum distribution for one-neutron removal from (24)O at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s_{1/2} neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that (24)O is a new doubly magic nucleus.
Additions to the spectrum and energy levels and critical compilation of doubly ionized boron, B III
NASA Astrophysics Data System (ADS)
Kramida, A. E.; Ryabtsev, A. N.; Ekberg, J. O.; Kink, I.; Mannervik, S.; Martinson, I.
2008-08-01
We have undertaken the study of the Li-like spectrum of doubly ionized boron, B III. The spectroscopic data have been obtained with beam-foil spectroscopy and high-resolution spark spectroscopy. The experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. About 50 new transitions have been observed, and most of the previously known lines have been measured with improved accuracy. We have also critically evaluated all previous and recent data for this spectrum. Complete data on wavelengths and energy levels based on this analysis are tabulated.
Skab, Ihor; Vasylkiv, Yuriy; Krupych, Oleh; Savaryn, Viktoriya; Vlokh, Rostyslav
2012-04-10
We show that a system of glass disks compressed along their diameters enables one to induce a doubly charged vortex beam in the emergent light when the incident light is circularly polarized. Using such a disk system, one can control the efficiency of conversion of the spin angular momentum to the orbital angular momentum by a loading force. The consideration presented here can be extended for the case of crystalline materials with high optical damage thresholds in order to induce high-power vortex beams.
The doubly Cabibbo-suppressed decay D+ → K+ π - π +
NASA Astrophysics Data System (ADS)
Aitala, E. M.; Amato, S.; Anjos, J. C.; Appel, J. A.; Ashery, D.; Banerjee, S.; Bediaga, I.; Blaylock, G.; Bracker, S. B.; Burchat, P. R.; Burnstein, R. A.; Carter, T.; Carvalho, H. S.; Copty, N. K.; Cremaldi, L. M.; Darling, C.; Denisenko, K.; Fernandez, A.; Gagnon, P.; Gounder, K.; Halling, A. M.; Herrera, G.; Hurvits, G.; James, C.; Kasper, P. A.; Kwan, S.; Langs, D. C.; Leslie, J.; Lundberg, B.; May Tal-Beck, S.; Meadows, B.; de Mello Neto, J. R. T.; Milburn, R. H.; de Miranda, J. M.; Napier, A.; Nguyen, A.; d'Oliveira, A. B.; O'Shaughnessy, K.; Peng, K. C.; Perera, L. P.; Purohit, M. V.; Quinn, B.; Radeztsky, S.; Rafatian, A.; Reay, N. W.; Reidy, J. J.; dos Reis, A. C.; Rubin, H. A.; Santha, A. K. S.; Santoro, A. F. S.; Schwartz, A. J.; Sheaff, M.; Sidwell, R. A.; Slaughter, A. J.; Sokoloff, M. D.; Stanton, N. R.; Stenson, K.; Summers, D. J.; Takach, S.; Thorne, K.; Tripathi, A. K.; Watanabe, S.; Weiss-Babai, R.; Wiener, J.; Witchey, N.; Wolin, E.; Yi, D.; Yoshida, S.; Zaliznyak, R.; Zhang, C.; Fermilab E791 Collaboration
1997-02-01
We report the observation of the doubly Cabibbo-suppressed decay D+ → K + π - π + in data from Fermilab charm hadroproduction experiment E791. With a signal of 59 ± 13 events we measured the ratio of the branching fraction for this mode to that of the Cabibbo-favored decay D+ → K- π + π + to be B(D + → K+ π - π +) / B( D + → K- π + π +) = (7.7 ± 1.7 ± 0.8) × 10 -3. A Dalitz plot analysis was performed to search for resonant structures.
A NASTRAN implementation of the doubly asymptotic approximation for underwater shock response
NASA Technical Reports Server (NTRS)
Everstine, G. C.
1976-01-01
A detailed description is given of how the decoupling approximation known as the doubly asymptotic approximation is implemented with NASTRAN to solve shock problems for submerged structures. The general approach involves locating the nonsymmetric terms (which couple structural and fluid variables) on the right hand side of the equations. This approach results in coefficient matrices of acceptable bandwidth but degrades numerical stability, requiring a smaller time step size than would otherwise be used. It is also shown how the structure's added (virtual) mass matrix, is calculated with NASTRAN.
In-plane rotation of the doubly coupled photonic crystal nanobeam cavities
NASA Astrophysics Data System (ADS)
Lin, Tong; Tian, Feng; Zhang, Wei; Zou, Yongchao; Chau, Fook Siong; Deng, Jie; Zhou, Guangya
2016-05-01
In this letter, a nano-electro-mechanical-systems (NEMS) mechanism is proposed to drive the in-plane rotation of the doubly coupled photonic crystal (PhC) nanobeam cavities. The corresponding interactions between optical resonances and rotations are investigated. This is the first in-plane rotational tuning of the PhC cavities, which benefits from the flexible design of NEMS actuators. In experiments, more than 18 linewidths of the third order TE even mode corresponding to 0.037 mrad of the shrinking angle between the two nanobeam cavities are demonstrated; this study provides one more mechanical degree of freedom for the practical optomechanical interactions.
NASA Technical Reports Server (NTRS)
Smillie, D. G.; Pickering, J. C.; Blackwell-Whitehead, R. J.; Smith, Peter L.; Nave, G.
2006-01-01
We report new measurements of doubly ionized iron group element spectra, important in the analysis of B-type (hot) stars whose spectra they dominate. These measurements include Co III and Cr III taken with the Imperial College VUV Fourier transform (FT) spectrometer and measurements of Co III taken with the normal incidence vacuum spectrograph at NIST, below 135 nm. We report new Fe III grating spectra measurements to complement our FT spectra. Work towards transition wavelengths, energy levels and branching ratios (which, combined with lifetimes, produce oscillator strengths) for these ions is underway.
Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei
NASA Astrophysics Data System (ADS)
Simenel, C.; Buete, J.; Vo-Phuoc, K.
2016-09-01
Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying vibrational modes for each of the nuclei were determined. Energies were found to be close to experimental results. However, transition amplitudes, quantified by the deformation parameter β3, are underestimated by TDHF. A comparison with single-particle excitations on the Hartree-Fock ground-state shows that the collective octupole vibrations have their energy lowered due to attractive RPA residual interaction.
One-neutron removal measurement reveals 24O as a new doubly magic nucleus.
Kanungo, R; Nociforo, C; Prochazka, A; Aumann, T; Boutin, D; Cortina-Gil, D; Davids, B; Diakaki, M; Farinon, F; Geissel, H; Gernhäuser, R; Gerl, J; Janik, R; Jonson, B; Kindler, B; Knöbel, R; Krücken, R; Lantz, M; Lenske, H; Litvinov, Y; Lommel, B; Mahata, K; Maierbeck, P; Musumarra, A; Nilsson, T; Otsuka, T; Perro, C; Scheidenberger, C; Sitar, B; Strmen, P; Sun, B; Szarka, I; Tanihata, I; Utsuno, Y; Weick, H; Winkler, M
2009-04-17
The first measurement of the momentum distribution for one-neutron removal from (24)O at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s_{1/2} neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that (24)O is a new doubly magic nucleus. PMID:19518623
Search for doubly charged Higgs bosons with lepton-flavor-violating decays involving tau leptons.
Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Giagu, S; Giakoumopolou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S
2008-09-19
We search for pair production of doubly charged Higgs particles (H+/- +/-) followed by decays into electron-tau (etau) and muon-tau (mutau) pairs using data (350 pb(-1) collected from [over]pp collisions at sqrt[s]=1.96 TeV by the CDF II experiment. We search separately for cases where three or four final-state leptons are detected, and combine results for exclusive decays to left-handed etau (mutau) pairs. We set an H+/- +/- lower mass limit of 114(112) GeV/c(2) at the 95% confidence level.
A rapid method for solving Laplace equation in a doubly connected region
NASA Astrophysics Data System (ADS)
Cai, R.; Zhu, Y.; Jiang, H.
1986-08-01
A power series expansion method (PSEM) is defined for modeling cascade flows by solving the Laplace equation inside of a doubly-connected region with well-defined inner and outer boundary conditions. The model is useful for analyzing both direct and inverse heat conduction problems, given accurate temperature and heat flux distributions along the boundaries. Analytical techniques are developed for applying the model for expansions along and normal to the boundary directions, in both cases obtaining results that are useful for engineering purposes without iterations or matrix calculation. Extensions of the model to three-dimensional calculations and to solving the Poisson equation and other partial differential equations are discussed.
X-ray optics and applications of doubly curved crystals in a symmetrical Bragg geometry
NASA Astrophysics Data System (ADS)
Seshadri, Srivatsan
This thesis primarily deals with the theoretical and experimental investigation of x-ray diffraction properties of doubly curved crystals in a symmetrical Bragg geometry. Theoretical expressions derived were applied to study the size and shape of the diffracting regions and the corresponding intensity profiles across the diffracting regions when the curved crystals are in the aligned or misaligned position with respect to a point source. Two geometries were studied: the Johann point focusing geometry and the Wittry geometry. Expressions were also derived to account for the broadening of the intensity profiles due to penetration of x-rays into the curved crystal, the finite source size and the natural linewidth of the characteristic x-ray fine and were applied to the above mentioned geometries to study these effects. Johann point focusing diffractors of mica were fabricated by photopolymerization method. This is the first time such a novel method is adopted to fabricate doubly curved diffractors. The diffraction and focusing properties of the diffractors were obtained by the use of microfocus x- ray source. These diffractors, were used to focus CuKα x-rays and the important parameters namely: intensity of the focused beam, sizes of the diffracting region and focus, the rocking curve width of mica, effective and actual diffraction efficiencies of the diffractor and the extinction parameter and extinction factor were determined. The application of doubly curved diffractors in the field of monochromatic microprobe x-ray fluorescence analysis (MMXRF) is also discussed. Theoretical expressions have been derived for intensity-concentration relationships to account for the convergence angles when a doubly curved diffractor is used for XRF analysis and applied to study the effects of convergence angles on the fluorescence intensities in NiFe and CrFe alloys. Crystal anisotropic elastic theory was also applied to study the effects of the crystal's anisotropy on the
Purely-long-range krypton molecules in singly and doubly excited binding potentials
Smith, Z. S.; Harmon, A.; Banister, J.; Norman, R.; Hoogeboom-Pot, K.; Walhout, M.
2010-01-15
Diatomic potentials for krypton are computed and also probed experimentally. For a probe-laser wavelength near 811 nm, several strong dipole-dipole interactions produce purely-long-range potential wells in the singly excited manifold of (s+p) potentials and in the doubly excited manifold of (p+p) and (s+d) potentials. Evidence of resonant photoassociation into bound states of these potential wells is observed in the emission of ions and ultraviolet photons from a magneto-optically trapped krypton cloud.
Power enhancement of burst-mode ultraviolet pulses using a doubly resonant optical cavity.
Rakhman, Abdurahim; Notcutt, Mark; Liu, Yun
2015-12-01
We report a doubly resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed, and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (1064 nm) and its frequency-tripled ultraviolet (355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber-optic frequency shifter. The DREC technique enables novel applications of optical cavities to power enhancement of burst-mode lasers with arbitrary macropulse width and repetition rate. PMID:26625051
Analysis of Coupled Reaction-Diffusion Equations for RNA Interactions
Hohn, Maryann E.; Li, Bo; Yang, Weihua
2015-01-01
We consider a system of coupled reaction-diffusion equations that models the interaction between multiple types of chemical species, particularly the interaction between one messenger RNA and different types of non-coding microRNAs in biological cells. We construct various modeling systems with different levels of complexity for the reaction, nonlinear diffusion, and coupled reaction and diffusion of the RNA interactions, respectively, with the most complex one being the full coupled reaction-diffusion equations. The simplest system consists of ordinary differential equations (ODE) modeling the chemical reaction. We present a derivation of this system using the chemical master equation and the mean-field approximation, and prove the existence, uniqueness, and linear stability of equilibrium solution of the ODE system. Next, we consider a single, nonlinear diffusion equation for one species that results from the slow diffusion of the others. Using variational techniques, we prove the existence and uniqueness of solution to a boundary-value problem of this nonlinear diffusion equation. Finally, we consider the full system of reaction-diffusion equations, both steady-state and time-dependent. We use the monotone method to construct iteratively upper and lower solutions and show that their respective limits are solutions to the reaction-diffusion system. For the time-dependent system of reaction-diffusion equations, we obtain the existence and uniqueness of global solutions. We also obtain some asymptotic properties of such solutions. PMID:25601722
Nonlinear waves in capillary electrophoresis
Ghosal, Sandip; Chen, Zhen
2011-01-01
Electrophoretic separation of a mixture of chemical species is a fundamental technique of great usefulness in biology, health care and forensics. In capillary electrophoresis the sample migrates in a microcapillary in the presence of a background electrolyte. When the ionic concentration of the sample is sufficiently high, the signal is known to exhibit features reminiscent of nonlinear waves including sharp concentration ‘shocks’. In this paper we consider a simplified model consisting of a single sample ion and a background electrolyte consisting of a single co-ion and a counterion in the absence of any processes that might change the ionization states of the constituents. If the ionic diffusivities are assumed to be the same for all constituents the concentration of sample ion is shown to obey a one dimensional advection diffusion equation with a concentration dependent advection velocity. If the analyte concentration is sufficiently low in a suitable non-dimensional sense, Burgers’ equation is recovered, and thus, the time dependent problem is exactly solvable with arbitrary initial conditions. In the case of small diffusivity either a leading edge or trailing edge shock is formed depending on the electrophoretic mobility of the sample ion relative to the background ions. Analytical formulas are presented for the shape, width and migration velocity of the sample peak and it is shown that axial dispersion at long times may be characterized by an effective diffusivity that is exactly calculated. These results are consistent with known observations from physical and numerical simulation experiments. PMID:20238181
NASA Astrophysics Data System (ADS)
Xu, Kui; Xu, Youyun; Zhang, Dongmei
2011-07-01
This paper analyzes the effect of the insufficient synchronization (carrier frequency offset, timing offset) on hexagonal multicarrier transmission (HMT) systems for doubly dispersive channel. Exact SINR and demodulated symbol expressions for HMT systems in the presence of insufficient synchronization transmission conditions over doubly dispersive channel with exponential delay power profile and U-shape Doppler power spectrum and uniform delay power profile and uniform Doppler power spectrum are derived, respectively. Theoretical analysis shows that similar degradations on symbol amplitude and phase caused by insufficient synchronization are incurred as in traditional cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) transmission. HMT systems outperform traditional OFDM systems with respect to signal to interference-plus-noise-ratio (SINR) against inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by insufficient synchronization and doubly dispersive(DD) channel. The BER performance of the HMT systems using Monte Carlo simulation match with the conclusion given by the proposed exact SINR expression.
Chirped Peregrine solitons in a class of cubic-quintic nonlinear Schrödinger equations
NASA Astrophysics Data System (ADS)
Chen, Shihua; Baronio, Fabio; Soto-Crespo, Jose M.; Liu, Yi; Grelu, Philippe
2016-06-01
We shed light on the fundamental form of the Peregrine soliton as well as on its frequency chirping property by virtue of a pertinent cubic-quintic nonlinear Schrödinger equation. An exact generic Peregrine soliton solution is obtained via a simple gauge transformation, which unifies the recently-most-studied fundamental rogue-wave species. We discover that this type of Peregrine soliton, viable for both the focusing and defocusing Kerr nonlinearities, could exhibit an extra doubly localized chirp while keeping the characteristic intensity features of the original Peregrine soliton, hence the term chirped Peregrine soliton. The existence of chirped Peregrine solitons in a self-defocusing nonlinear medium may be attributed to the presence of self-steepening effect when the latter is not balanced out by the third-order dispersion. We numerically confirm the robustness of such chirped Peregrine solitons in spite of the onset of modulation instability.
Exact solutions for logistic reaction-diffusion equations in biology
NASA Astrophysics Data System (ADS)
Broadbridge, P.; Bradshaw-Hajek, B. H.
2016-08-01
Reaction-diffusion equations with a nonlinear source have been widely used to model various systems, with particular application to biology. Here, we provide a solution technique for these types of equations in N-dimensions. The nonclassical symmetry method leads to a single relationship between the nonlinear diffusion coefficient and the nonlinear reaction term; the subsequent solutions for the Kirchhoff variable are exponential in time (either growth or decay) and satisfy the linear Helmholtz equation in space. Example solutions are given in two dimensions for particular parameter sets for both quadratic and cubic reaction terms.
NASA Astrophysics Data System (ADS)
Lauterborn, Werner; Kurz, Thomas; Akhatov, Iskander
At high sound intensities or long propagation distances at
Numerical evaluation of lateral diffusion inside diffusive gradients in thin films samplers.
Santner, Jakob; Kreuzeder, Andreas; Schnepf, Andrea; Wenzel, Walter W
2015-05-19
Using numerical simulation of diffusion inside diffusive gradients in thin films (DGT) samplers, we show that the effect of lateral diffusion inside the sampler on the solute flux into the sampler is a nonlinear function of the diffusion layer thickness and the physical sampling window size. In contrast, earlier work concluded that this effect was constant irrespective of parameters of the sampler geometry. The flux increase caused by lateral diffusion inside the sampler was determined to be ∼8.8% for standard samplers, which is considerably lower than the previous estimate of ∼20%. Lateral diffusion is also propagated to the diffusive boundary layer (DBL), where it leads to a slightly stronger decrease in the mass uptake than suggested by the common 1D diffusion model that is applied for evaluating DGT results. We introduce a simple correction procedure for lateral diffusion and demonstrate how the effect of lateral diffusion on diffusion in the DBL can be accounted for. These corrections often result in better estimates of the DBL thickness (δ) and the DGT-measured concentration than earlier approaches and will contribute to more accurate concentration measurements in solute monitoring in waters.
Numerical Evaluation of Lateral Diffusion Inside Diffusive Gradients in Thin Films Samplers
2015-01-01
Using numerical simulation of diffusion inside diffusive gradients in thin films (DGT) samplers, we show that the effect of lateral diffusion inside the sampler on the solute flux into the sampler is a nonlinear function of the diffusion layer thickness and the physical sampling window size. In contrast, earlier work concluded that this effect was constant irrespective of parameters of the sampler geometry. The flux increase caused by lateral diffusion inside the sampler was determined to be ∼8.8% for standard samplers, which is considerably lower than the previous estimate of ∼20%. Lateral diffusion is also propagated to the diffusive boundary layer (DBL), where it leads to a slightly stronger decrease in the mass uptake than suggested by the common 1D diffusion model that is applied for evaluating DGT results. We introduce a simple correction procedure for lateral diffusion and demonstrate how the effect of lateral diffusion on diffusion in the DBL can be accounted for. These corrections often result in better estimates of the DBL thickness (δ) and the DGT-measured concentration than earlier approaches and will contribute to more accurate concentration measurements in solute monitoring in waters. PMID:25877251
Energy expenditure in space flight (doubly labelled water method) (8-IML-1)
NASA Technical Reports Server (NTRS)
Parsons, Howard G.
1992-01-01
The objective of the Energy Expenditure in Space Flight (ESS) experiment is to demonstrate and evaluate the doubly labeled water method of measuring the energy expended by crew members during approximately 7 days in microgravity. The doubly labeled water technique determines carbon dioxide production which is then used to calculate energy expenditure. The method relies on the equilibrium between oxygen in respiratory carbon dioxide and oxygen in body water. Because of this equilibrium, the kinetic of water turnover and respiration are interdependent. Under normal conditions, man contains small but significant amounts of deuterium and oxygen 18. Deuterium is eliminated from the body as water while oxygen 18 is eliminated as water and carbon dioxide. The difference in the turnover rates in the two isotopes is proportional to the carbon dioxide production. Deliberately enriching the total body water with both of these isotopes allows the isotope turnovers to be accurately measured in urine, plasma, or saliva samples. The samples are taken to the laboratory for analysis using an ion-ratio spectrometer.
Bai, Xiaofei; Tsiatis, Anastasios A; O'Brien, Sean M
2013-12-01
Observational studies are frequently conducted to compare the effects of two treatments on survival. For such studies we must be concerned about confounding; that is, there are covariates that affect both the treatment assignment and the survival distribution. With confounding the usual treatment-specific Kaplan-Meier estimator might be a biased estimator of the underlying treatment-specific survival distribution. This article has two aims. In the first aim we use semiparametric theory to derive a doubly robust estimator of the treatment-specific survival distribution in cases where it is believed that all the potential confounders are captured. In cases where not all potential confounders have been captured one may conduct a substudy using a stratified sampling scheme to capture additional covariates that may account for confounding. The second aim is to derive a doubly-robust estimator for the treatment-specific survival distributions and its variance estimator with such a stratified sampling scheme. Simulation studies are conducted to show consistency and double robustness. These estimators are then applied to the data from the ASCERT study that motivated this research. PMID:24117096
Bai, Xiaofei; Tsiatis, Anastasios A.; O'Brien, Sean M.
2013-01-01
Summary Observational studies are frequently conducted to compare the effects of two treatments on survival. For such studies we must be concerned about confounding; that is, there are covariates that affect both the treatment assignment and the survival distribution. With confounding the usual treatment-specific Kaplan-Meier estimator might be a biased estimator of the underlying treatment-specific survival distribution. This paper has two aims. In the first aim we use semiparametric theory to derive a doubly robust estimator of the treatment-specific survival distribution in cases where it is believed that all the potential confounders are captured. In cases where not all potential confounders have been captured one may conduct a substudy using a stratified sampling scheme to capture additional covariates that may account for confounding. The second aim is to derive a doubly-robust estimator for the treatment-specific survival distributions and its variance estimator with such a stratified sampling scheme. Simulation studies are conducted to show consistency and double robustness. These estimators are then applied to the data from the ASCERT study that motivated this research. PMID:24117096
A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory
Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung
2015-03-04
A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to account for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.
A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory
Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung
2015-03-04
A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to accountmore » for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.« less
Conversions of bound muons: Lepton flavor violation from doubly charged scalars
NASA Astrophysics Data System (ADS)
Geib, Tanja; Merle, Alexander
2016-03-01
We present the first detailed computation of the conversion of a bound muon into an electron mediated by a doubly charged S U (2 ) singlet scalar. Although such particles are not too exotic, up to now their contribution to μ -e conversion is unknown. We close this gap by presenting a detailed calculation, which will allow the reader not only to fully comprehend the discussion but also to generalize our results to similar cases if needed. We furthermore compare the predictions, for both the general case and an example model featuring a neutrino mass at two-loop level, to current experimental data and future sensitivities. We show that, depending on the explicit values of the couplings as well as on the actual future limits on the branching ratio, μ -e conversion may potentially yield a lower limit on the doubly charged singlet scalar mass, which is stronger than what could be obtained by colliders. Our results considerably strengthen the case for low-energy lepton flavor violation searches being a very valuable addition to collider experiments.
Sensitivity of methods for calculating energy expenditure by use of doubly labeled water.
Seale, J; Miles, C; Bodwell, C E
1989-02-01
Attempts to estimate human energy expenditure by use of doubly labeled water have produced three methods currently used for calculating carbon dioxide production from isotope disappearance data: 1) the two-point method, 2) the regression method, and 3) the integration method. An ideal data set was used to determine the error produced in the calculated energy expenditure for each method when specific variables were perturbed. The analysis indicates that some of the calculation methods are more susceptible to perturbations in certain variables than others. Results from an experiment on one adult human subject are used to illustrate the potential for error in actual data. Samples of second void urine, 24-h urine, and breath collected every other day for 21 days are used to calculate the average daily energy expenditure by three calculation methods. The difference between calculated energy expenditure and metabolizable energy on a weight-maintenance diet is used to estimate the error associated with the doubly labeled water method. PMID:2496076
Partial cross sections of doubly excited helium below the ionization threshold I{sub 7}
Jiang, Y.H.; Puettner, R.; Poiguine, M.; Kaindl, G.; Hentges, R.; Viefhaus, J.; Becker, U.; Rost, J.M.
2004-04-01
Partial photoionization cross sections (PCSs), {sigma}{sub n}, leading to final ionic states of helium, He{sup +}(n), were measured at BESSY II in the region of doubly excited helium up to the ionization threshold I{sub 7} of He{sup +}. The experiments were performed with a time-of-flight (TOF) electron spectrometer and high photon resolution, {delta}E congruent with 6 meV. The results of these measurements are a most critical assessment of the decay dynamics of double-excitation resonances and agree well with those of recent eigenchannel R-matrix calculations. They also confirm the propensity rules set up for the autoionization of doubly excitated states. The mirroring behavior in the PCSs predicted recently by Liu and Starace is only partially observed. By discussing the formulas given by these authors in a more general context, the specific behavior of the PCSs of helium with respect to mirroring can be understood. The mirroring compensation properties between the 'fractional partial cross sections' {gamma}{sub P}={sigma}{sub P}/{sigma}{sub T} and {gamma}{sub Q}={sigma}{sub Q}/{sigma}{sub T}, with {sigma}{sub T}={sigma}{sub P}+{sigma}{sub Q}, are introduced and discussed.
Lensless coded-aperture imaging with separable Doubly-Toeplitz masks
NASA Astrophysics Data System (ADS)
DeWeert, Michael J.; Farm, Brian P.
2015-02-01
In certain imaging applications, conventional lens technology is constrained by the lack of materials which can effectively focus the radiation within a reasonable weight and volume. One solution is to use coded apertures-opaque plates perforated with multiple pinhole-like openings. If the openings are arranged in an appropriate pattern, then the images can be decoded and a clear image computed. Recently, computational imaging and the search for a means of producing programmable software-defined optics have revived interest in coded apertures. The former state-of-the-art masks, modified uniformly redundant arrays (MURAs), are effective for compact objects against uniform backgrounds, but have substantial drawbacks for extended scenes: (1) MURAs present an inherently ill-posed inversion problem that is unmanageable for large images, and (2) they are susceptible to diffraction: a diffracted MURA is no longer a MURA. We present a new class of coded apertures, separable Doubly-Toeplitz masks, which are efficiently decodable even for very large images-orders of magnitude faster than MURAs, and which remain decodable when diffracted. We implemented the masks using programmable spatial-light-modulators. Imaging experiments confirmed the effectiveness of separable Doubly-Toeplitz masks-images collected in natural light of extended outdoor scenes are rendered clearly.
NASA Technical Reports Server (NTRS)
Horvitz, M. A.; Schoeller, D. A.
2001-01-01
The doubly labeled water method for measuring total energy expenditure is subject to error from natural variations in the background 2H and 18O in body water. There is disagreement as to whether the variations in background abundances of the two stable isotopes covary and what relative doses of 2H and 18O minimize the impact of variation on the precision of the method. We have performed two studies to investigate the amount and covariance of the background variations. These were a study of urine collected weekly from eight subjects who remained in the Madison, WI locale for 6 wk and frequent urine samples from 14 subjects during round-trip travel to a locale > or = 500 miles from Madison, WI. Background variation in excess of analytical error was detected in six of the eight nontravelers, and covariance was demonstrated in four subjects. Background variation was detected in all 14 travelers, and covariance was demonstrated in 11 subjects. The median slopes of the regression lines of delta2H vs. delta18O were 6 and 7, respectively. Modeling indicated that 2H and 18O doses yielding a 6:1 ratio of final enrichments should minimize this error introduced to the doubly labeled water method.
Abundance and Impact of Doubly Charged Polyatomic Argon Interferences in ICPMS Spectra.
Hattendorf, Bodo; Gusmini, Bianca; Dorta, Ladina; Houk, Robert S; Günther, Detlef
2016-07-19
Doubly charged molecular ions of alkaline earth metals and argon could be identified as spectral interferences in an inductively coupled plasma mass spectrometer. These molecular ions were found to occur at abundances reaching about 10(-4) relative to the alkaline earth atomic ion abundances. They can thus substantially affect ultratrace analyses and, when present at similar concentration as the analyte elements, also isotope ratio measurements. For the case of Cu and Zn isotope ratio analyses, the same mass concentration of Sr was found to alter the measured (63)Cu/(65)Cu and (64)Zn/(66)Zn isotope ratios by -0.036‰ to -0.95‰ due to SrAr(2+), appearing at m/Q 63 and 64. BaAr(2+) can affect Sr isotope analyses, MgAr(2+) may impair S isotope ratio measurements, while CaAr(2+) may cause interference to Ca(+) isotopes. The abundances of the doubly charged molecular ions were higher than those of the corresponding singly charged species, which is in accordance with their generally higher bond dissociation energies. The relative abundances were found to depend significantly on the inductively coupled plasma (ICP) operating conditions and generally increase with increasing carrier gas flow rates or lower gas temperature of the ICP. They also increase by about an order of magnitude when a desolvated aerosol is introduced to the ICP. PMID:27306032
NASA Astrophysics Data System (ADS)
Liigand, Piia; Kaupmees, Karl; Kruve, Anneli
2016-07-01
The ability of polyprotic acids to give doubly charged ions in negative mode electrospray was studied and related to physicochemical properties of the acids via linear discriminant analysis (LDA). It was discovered that the compound has to be strongly acidic (low p K a1 and p K a2) and to have high hydrophobicity (log P ow) to become multiply charged. Ability to give multiply charged ions in ESI/MS cannot be directly predicted from the solution phase acidities. Therefore, for the first time, a quantitative model to predict the charge state of the analyte in ESI/MS is proposed and validated for small anions. Also, a model to predict ionization efficiencies of these analytes was developed. Results indicate that acidity of the analyte, its octanol-water partition coefficient, and charge delocalization are important factors that influence ionization efficiencies as well as charge states of the analytes. The pH of the solvent was also found to be an important factor influencing the ionization efficiency of doubly charged ions.
NASA Astrophysics Data System (ADS)
CUNNINGHAM, P. R.; WHITE, R. G.; AGLIETTI, G. S.
2000-02-01
Sandwich panels have a very high stiffness to weight ratio, which makes them particularly useful in the aerospace industry where carbon fibre reinforced plastics and lightweight honeycomb cores are being used in the construction of floor panels, fairings and intake barrel panels. In the latter case, the geometry of the panels can be considered doubly curved. This paper presents an introduction to an ongoing study investigating the dynamic response prediction of acoustically excited composite sandwich panels which have double curvature. The final objective is to assess and hopefully produce an up to date set of acoustic fatigue design guidelines for this type of structure. The free vibration of doubly curved composite honeycomb sandwich panels is investigated here, both experimentally and theoretically, the latter using a commerically available finite element package. The design and manufacture of three test panels is covered before presenting experimental results for the natural frequencies of vibration with freely supported boundary conditions. Once validated against the experimental results, the theoretical investigation is extended to study the effects of changing radii of curvature, orthotropic properties of the core, and ply orientation on the natural frequencies of vibration of rectangular panels with various boundary conditions. The results from the parameter studies show curve veering, particularly when studying the effect of changing radii and ply orientation, however, it is not clear whether this phenomenon is due to the approximation method used or occurs in the physical system.
NASA Technical Reports Server (NTRS)
Smith, Peter L.; Pickering, Juliet C.; Thorne, A. P.
2002-01-01
Currently available laboratory spectroscopic data of doubly ionized iron-group element were obtained about 50 years ago using spectrographs of modest dispersion, photographic plates, and eye estimates of intensities. The accuracy of the older wavelength data is about 10 mAngstroms at best, whereas wavelengths are now needed to an accuracy of 1 part in 10(exp 6) to 10(exp 7) (0.2 to 2 mAngstroms at 2000 Angstroms). The Fourier transform (FT) spectroscopy group at Imperial College, London, and collaborators at the Harvard College Observatory have used a unique VUV FT spectrometer in a program focussed on improving knowledge of spectra of many neutral and singly and doubly ionized, astrophysically important, iron group elements. Spectra of Fe II and Fe III have been recorded at UV and VUV wavelengths with signal-to-noise ratios of several hundred for the stronger lines. Wavelengths and energy levels for Fe III are an order of magnitude more accurate than previous work; analysis is close to completion. f-values for Fe II have been published.
Photoionization study of doubly-excited helium at ultra-high resolution
Kaindl, G.; Schulz, K.; Domke, M.
1997-04-01
Ever since the pioneering work of Madden & Codling and Cooper, Fano & Prats on doubly-excited helium in the early sixties, this system may be considered as prototypical for the study of electron-electron correlations. More detailed insight into these states could be reached only much later, when improved theoretical calculations of the optically-excited {sup 1}P{sup 0} double-excitation states became available and sufficiently high energy resolution ({delta}E=4.0 meV) was achieved. This allowed a systematic investigation of the double-excitation resonances of He up to excitation energies close to the double-ionization threshold, I{sub infinity}=79.003 eV, which stimulated renewed theoretical interest into these correlated electron states. The authors report here on striking progress in energy resolution in this grazing-incidence photon-energy range of grating monochromators and its application to hitherto unobservable states of doubly-excited He. By monitoring an extremely narrow double-excitation resonance of He, with a theoretical lifetime width of less than or equal to 5 {mu}eV, a resolution of {delta}E=1.0 meV (FWHM) at 64.1 eV could be achieved. This ultra-high spectral resolution, combined with high photon flux, allowed the investigation of new Rydberg resonances below the N=3 ionization threshold, I{sub 3}, as well as a detailed comparison with ab-initio calculations.
Abundance and Impact of Doubly Charged Polyatomic Argon Interferences in ICPMS Spectra.
Hattendorf, Bodo; Gusmini, Bianca; Dorta, Ladina; Houk, Robert S; Günther, Detlef
2016-07-19
Doubly charged molecular ions of alkaline earth metals and argon could be identified as spectral interferences in an inductively coupled plasma mass spectrometer. These molecular ions were found to occur at abundances reaching about 10(-4) relative to the alkaline earth atomic ion abundances. They can thus substantially affect ultratrace analyses and, when present at similar concentration as the analyte elements, also isotope ratio measurements. For the case of Cu and Zn isotope ratio analyses, the same mass concentration of Sr was found to alter the measured (63)Cu/(65)Cu and (64)Zn/(66)Zn isotope ratios by -0.036‰ to -0.95‰ due to SrAr(2+), appearing at m/Q 63 and 64. BaAr(2+) can affect Sr isotope analyses, MgAr(2+) may impair S isotope ratio measurements, while CaAr(2+) may cause interference to Ca(+) isotopes. The abundances of the doubly charged molecular ions were higher than those of the corresponding singly charged species, which is in accordance with their generally higher bond dissociation energies. The relative abundances were found to depend significantly on the inductively coupled plasma (ICP) operating conditions and generally increase with increasing carrier gas flow rates or lower gas temperature of the ICP. They also increase by about an order of magnitude when a desolvated aerosol is introduced to the ICP.
Spectroscopy of doubly and triply-charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2013-11-01
We present the ground and excited state spectra of doubly and triply-charmed baryons by using lattice QCD with dynamical clover fermions. A large set of baryonic operators that respect the symmetries of the lattice and are obtained after subduction from their continuum analogues are utilized. Using novel computational techniques correlation functions of these operators are generated and the variational method is exploited to extract excited states. The lattice spectra that we obtain have baryonic states with well-defined total spins up to 7/2 and the low lying states remarkably resemble the expectations of quantum numbers from SU(6) Ⓧ O(3) symmetry. Various energy splittings between the extracted states, including splittings due to hyperfine as well as spin-orbit coupling, are considered and those are also compared against similar energy splittings at other quark masses. Using those splittings for doubly-charmed baryons, and taking input of experimental Bc meson mass, we predict the mass splittings of B*c-Bc to be about 80 ± 8 MeV and mΩccb=8050±10 MeV.
Nonlinear Hysteretic Torsional Waves
NASA Astrophysics Data System (ADS)
Cabaret, J.; Béquin, P.; Theocharis, G.; Andreev, V.; Gusev, V. E.; Tournat, V.
2015-07-01
We theoretically study and experimentally report the propagation of nonlinear hysteretic torsional pulses in a vertical granular chain made of cm-scale, self-hanged magnetic beads. As predicted by contact mechanics, the torsional coupling between two beads is found to be nonlinear hysteretic. This results in a nonlinear pulse distortion essentially different from the distortion predicted by classical nonlinearities and in a complex dynamic response depending on the history of the wave particle angular velocity. Both are consistent with the predictions of purely hysteretic nonlinear elasticity and the Preisach-Mayergoyz hysteresis model, providing the opportunity to study the phenomenon of nonlinear dynamic hysteresis in the absence of other types of material nonlinearities. The proposed configuration reveals a plethora of interesting phenomena including giant amplitude-dependent attenuation, short-term memory, as well as dispersive properties. Thus, it could find interesting applications in nonlinear wave control devices such as strong amplitude-dependent filters.
Tomlin, R.
1990-01-27
A nonlinear oscillator design was imported from Cornell modified, and built for the purpose of simulating the chaotic states of a forced pendulum. Similar circuits have been investigated in the recent nonlinear explosion.
Wang, Chi-Jen
2013-01-01
In this thesis, we analyze both the spatiotemporal behavior of: (A) non-linear “reaction” models utilizing (discrete) reaction-diffusion equations; and (B) spatial transport problems on surfaces and in nanopores utilizing the relevant (continuum) diffusion or Fokker-Planck equations. Thus, there are some common themes in these studies, as they all involve partial differential equations or their discrete analogues which incorporate a description of diffusion-type processes. However, there are also some qualitative differences, as shall be discussed below.
NASA Astrophysics Data System (ADS)
Renganathan, Sindhuja; White, Ralph E.
A semianalytical methodology based on the integral transform technique is proposed to solve the diffusion equation with concentration dependent diffusion coefficient in a spherical intercalation electrode particle. The method makes use of an integral transform pair to transform the nonlinear partial differential equation into a set of ordinary differential equations, which is solved with less computational efforts. A general solution procedure is presented and two illustrative examples are used to demonstrate the usefulness of this method for modeling of diffusion process in lithium ion battery electrode. The solutions obtained using the method presented in this study are compared to the numerical solutions.
A Huygens principle for diffusion and anomalous diffusion in spatially extended systems
Gottwald, Georg A.; Melbourne, Ian
2013-01-01
We present a universal view on diffusive behavior in chaotic spatially extended systems for anisotropic and isotropic media. For anisotropic systems, strong chaos leads to diffusive behavior (Brownian motion with drift) and weak chaos leads to superdiffusive behavior (Lévy processes with drift). For isotropic systems, the drift term vanishes and strong chaos again leads to Brownian motion. We establish the existence of a nonlinear Huygens principle for weakly chaotic systems in isotropic media whereby the dynamics behaves diffusively in even space dimension and exhibits superdiffusive behavior in odd space dimensions. PMID:23653481
Mach, H.; Fogelberg, B.; Jacobsson, L.; Lindroth, A.; Sanchez-Vega, M.; Taylor, R. B. E.; Blomqvist, J.; Isakov, V. I.; Mezilev, K. A.
1998-12-21
A brief description of the OSIRIS fission product mass separator and an outline of the current program of research in the domain of nuclear structure at the doubly magic {sup 132}Sn region are given. The most recent results on the study of the single particle states in {sup 133}Sb are briefly summarized.
Champion, Christophe; Quinto, Michele A.; Bug, Marion U.; Baek, Woon Y.; Weck, Philippe F.
2014-07-29
Electron-induced ionization of the commonly used surrogate of the DNA sugar-phosphate backbone, namely, the tetrahydrofuran molecule, is here theoretically described within the 1st Born approximation by means of quantum-mechanical approach. Comparisons between theory and recent experiments are reported in terms of doubly and singly differential cross sections.
Champion, Christophe; Quinto, Michele A.; Bug, Marion U.; Baek, Woon Y.; Weck, Philippe F.
2014-07-29
Electron-induced ionization of the commonly used surrogate of the DNA sugar-phosphate backbone, namely, the tetrahydrofuran molecule, is here theoretically described within the 1^{st} Born approximation by means of quantum-mechanical approach. Comparisons between theory and recent experiments are reported in terms of doubly and singly differential cross sections.
NASA Astrophysics Data System (ADS)
Champion, Christophe; Quinto, Michele A.; Bug, Marion U.; Baek, Woon Y.; Weck, Philippe F.
2014-07-01
Electron-induced ionization of the tetrahydrofuran molecule, the commonly used surrogate of the DNA sugar-phosphate backbone, is theoretically described in this study within the 1st Born approximation. Comparisons between theory and recent experiments are reported in terms of doubly and singly differential cross sections.
A Newborn Asteroid Family of Likely Rotational Origin Harboring a Doubly-Synchronous Binary
NASA Astrophysics Data System (ADS)
Drahus, Michal; Waniak, Waclaw
2016-10-01
From the total number of about twenty active asteroids identified to date, one of the most intriguing is P/2012 F5. The 2-km sized object has a short rotation period of 3.24 hr – the shortest known among main-belt active asteroids and comets – and is trailed by several fragments recently separated from the main nucleus (Drahus et al. 2015, ApJL 802, L8). Our extensive observations with Hubble in late 2015 and early 2016 have revealed that the fragments are real and stable "baby asteroids", still cocooned in their birth dust trail. Consequently, P/2012 F5 is the first known asteroid family forming in the present-day epoch. Given the rapid spin of the main nucleus, the system is also the best candidate for the first "rotational" asteroid family originating from rotational fission (as opposed to the long-known "collisional" families), extending the recently identified class of asteroid pairs (Pravec et al. 2010, Nature 466, 1085). Furthermore, the HST data allowed us to measure a light curve of the brightest fragment of P/2012 F5, several magnitudes fainter than the main nucleus. The light curve has all the characteristics of a close binary with significantly elongated, roughly equal sized components, having equal rotation and orbital periods of about 9 hr. The existence of a doubly-synchronous binary in an ultra-young asteroid family is seemingly inconsistent with the established "slow" binary formation path, in which YORP torques first lead to rotational fission and then tides lead to synchronization (Jacobson & Scheeres 2011, Icarus 214, 161). Instead, we believe that the object fissioned while orbiting the main nucleus and drawing its angular momentum, and was subsequently ejected from the system as a finished doubly-synchronous binary. This scenario is consistent with computer simulations in that the timescales for secondary fission and ejection from the system are indeed very short (Jacobson & Scheeres 2011, Icarus 214, 161). But the empirical evidence that
Spectroscopic study and astronomical detection of doubly 13C-substituted ethyl cyanide
NASA Astrophysics Data System (ADS)
Margulès, L.; Belloche, A.; Müller, H. S. P.; Motiyenko, R. A.; Guillemin, J.-C.; Garrod, R. T.; Menten, K. M.
2016-05-01
Context. We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly 13C-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly 13C-substituted isotopomers should also be detectable. Aims: We want to determine the spectroscopic parameters of all three doubly 13C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. Methods: We investigated the laboratory rotational spectra of the three species between 150 GHz and 990 GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the 12C and singly 13C-substituted isotopologues assuming local thermodynamic equilibrium. Results: We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three doubly 13C-substituted isotopomers. The quantum numbers reach J ≈ 115 and Ka ≈ 35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations beyond 1000 GHz for strong to moderately weak transitions of either isotopomer. All three species are unambiguously detected in our ALMA data. The 12C/13C column density ratio of the isotopomers with one 13C atom to those with two 13C atoms is about 25. Conclusions: Ethyl cyanide is the second molecule after methyl cyanide for which isotopologues containing two 13C atoms have been securely detected in the interstellar medium. The model of our ethyl cyanide data suggests that we should be able to detect vibrational satellites of the main species up to at least ν19 = 1 at ~1130 K and up to ν13 + ν21 = 2 at ~600 K for the isotopologues with one 13C atom in
Manifestation of the Kondo effect in nonlinear optical absorption
NASA Astrophysics Data System (ADS)
Shahbazyan, T. V.; Perakis, I. E.; Raikh, M. E.
2000-03-01
We study the nonlinear optical absorption due to transitions from a deep impurity to states above a Fermi sea. Previous calculations(See, e.g., S. Mukamel, Principles of Nonlinear Optical Spectroscopy), (Oxford University Press, 1995). of \\chi^(3) included contributions from virtual processes involving doubly occupied impurity state. This indicates the necessity of incorporating the Hubbard repulsion of electrons at the impurity in calculation of nonlinear optical properties. Detailed calculations are performed for pump-probe spectrum. We demonstrate that Hubbard-repulsion-induced suppression of two-electron states leads to the divergency in \\chi^(3) near the absorption threshold. The origin of this divergency lies in the Kondo-physics;(See, e.g., A. C. Hewson, The Kondo Problem to Heavy Fermions), (Cambridge University Press, 1993). a monochromatic optical field induces the coupling between the impurity and conduction band states that is similar to the hybridization terms in the Anderson model.^3 Remarkably, for light-induced Kondo-absorption, the Kondo temperature can be tuned by the intensity and frequency of the pump field.
Excitation of {sup 1}S and {sup 3}S Metastable Helium Atoms to Doubly Excited States
Alagia, M.; Coreno, M.; Farrokhpour, H.; Omidyan, R.; Tabrizchi, M.; Franceschi, P.; Mihelic, A.; Zitnik, M.; Moise, A.; Prince, K. C.; Richter, R.; Soederstroem, J.; Stranges, S.
2009-04-17
We present spectra of triplet and singlet metastable helium atoms resonantly photoexcited to doubly excited states. The first members of three dipole-allowed {sup 1,3}P{sup o} series have been observed and their relative photoionization cross sections determined, both in the triplet (from 1s2s {sup 3}S{sup e}) and singlet (from 1s2s {sup 1}S{sup e}) manifolds. The intensity ratios are drastically different with respect to transitions from the ground state. When radiation damping is included the results for the singlets are in agreement with theory, while for triplets spin-orbit interaction must also be taken into account.
High spin states and isomeric decays in doubly-odd 208Fr
NASA Astrophysics Data System (ADS)
Kanjilal, D.; Bhattacharya, S.; Goswami, A.; Kshetri, R.; Raut, R.; Saha, S.; Bhowmik, R. K.; Gehlot, J.; Muralithar, S.; Singh, R. P.; Jnaneswari, G.; Mukherjee, G.; Mukherjee, B.
2010-10-01
Neutron deficient isotopes of francium ( Z=87, N˜121-123) as excited nuclei were produced in the fusion-evaporation reaction: 197Au( 16O, xn) 213 - xFr at 100 MeV. The γ rays from the residues were observed through the high sensitivity Germanium Clover detector array INGA. The decay of the high spin states and the isomeric states of the doubly-odd 208Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half-lives of the E=194(2) keV isomeric transition, known from earlier observations, was measured to be T=233(18) ns. A second isomeric transition at E=383(2) keV and T=33(7) ns was also found. The measured half-lives were compared with the corresponding single particle estimates, based on the level scheme obtained from the experiment.
An inductively coupled, doubly tuned resonator for in vivo nuclear magnetic resonance spectroscopy
NASA Astrophysics Data System (ADS)
McNichols, Roger J.; Wright, Steven M.; Wasser, Jeremy S.; Coté, Gerard L.
1999-08-01
We present a coil designed for in vivo 31P and 1H nuclear magnetic resonance spectroscopy which consists of a doubly tuned resonator inductively coupled to separate 1H and 31P feed coils. The advantages of the resonator include the ability to 1H shim over the same volume from which 31P spectra are extracted by using a single sample coil, elimination of coupling problems between separate 1H and 31P coils, ease of design and tuning over conventional double-tuned coils, and reduced match/tune sensitivity to coil loading, which is important in in vivo applications. We have used this coil to collect phosphorus spectra from the in situ heart of the western painted turtle (Chrysemys picta bellii) at 2 T. The total heart volume was less than 1 mL and acquisition time was just under 10 min.
Diode-pumped doubly resonant all-intracavity continuous-wave ultraviolet laser at 336 nm
NASA Astrophysics Data System (ADS)
Lü, Y. F.; Sun, G. C.; Fu, X. H.; Liu, Z. T.; Chen, J. F.
2010-08-01
We report for the first time a coherent ultraviolet radiation at 336 nm by intracavity sum-frequency generation of a 912 nm Nd:GdVO4 laser and a 532 nm frequency doubling Nd:YVO4 laser. The ultraviolet laser is obtained by using a doubly resonator, type-I critical phase matching CsLiB6O10 (CLBO) crystal sum-frequency mixing. With a total diode pump power of 31.8 W (13.1 W pump power for 912 nm Nd:GdVO4 laser and 18.7 W pump power for 532 nm Nd:YVO4 frequency doubling laser), TEM00 mode ultraviolet laser at 336 nm of 93 mW is obtained. The power stability is better than 3.4% and laser beam quality M2 factors are 1.52 and 1.27 in both horizontal and vertical dimensions respectively.
Search for doubly charged Higgs bosons with lepton-flavour-violating decays involving tau leptons
Aaltonen, T.
2007-12-01
The authors search for pair production of doubly charged Higgs particles (H{sup {+-}{+-}}) followed by decays into electron-tau (e{tau}) and muon-tau ({mu}{tau}) pairs using a data set corresponding to an integrated luminosity of 350 pb{sup -1} collected from {bar p}p collisions at {radical}s = 1.96 TeV by the CDF II experiment. They search separately for cases where three or four final-state leptons are detected, and then combine the results into limits for each exclusive flavor decay mode of the H{sup {+-}{+-}}. Assuming 100% branching ratios of the H{sup {+-}{+-}} to left-handed e{tau} ({mu}{tau}) pairs, they set an H{sup {+-}{+-}} lower mass limit of 114 (112) GeV/c{sup 2} at the 95% confidence level (C.L.).
Doubly Magic Nucleus {sub 108}{sup 270}Hs{sub 162}
Dvorak, J.; Kruecken, R.; Nebel, F.; Novackova, Z.; Tuerler, A.; Wierczinski, B.; Yakushev, A.; Bruechle, W.; Jaeger, E.; Schaedel, M.; Schausten, B.; Schimpf, E.; Chelnokov, M.; Gorshkov, V.; Kuznetsov, A.; Yeremin, A.; Dressler, R.; Duellmann, Ch. E.; Eberhardt, K.; Thoerle, P.
2006-12-15
Theoretical calculations predict {sup 270}Hs (Z=108, N=162) to be a doubly magic deformed nucleus, decaying mainly by {alpha}-particle emission. In this work, based on a rapid chemical isolation of Hs isotopes produced in the {sup 26}Mg+{sup 248}Cm reaction, we observed 15 genetically linked nuclear decay chains. Four chains were attributed to the new nuclide {sup 270}Hs, which decays by {alpha}-particle emission with Q{sub {alpha}}=9.02{+-}0.03 MeV to {sup 266}Sg which undergoes spontaneous fission with a half-life of 444{sub -148}{sup +444} ms. A production cross section of about 3 pb was measured for {sup 270}Hs. Thus, {sup 270}Hs is the first nucleus for which experimental nuclear decay properties have become available for comparison with theoretical predictions of the N=162 shell stability.
Excited-state spectroscopy of singly, doubly and triply-charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2014-07-01
We present the ground and excited state spectra of singly, doubly and triply-charmed baryons by using dynamical lattice QCD. A large set of baryonic operators that respect the symmetries of the lattice and are obtained after subduction from their continuum analogues are utilized. These operators transform as irreducible representations of SU(3)F symmetry for flavour, SU(4) symmetry for Dirac spins of quarks and O(3) symmetry for orbital angular momenta. Using novel computational techniques correlation functions of these operators are generated and the variational method is exploited to extract excited states. The lattice spectra that we obtain have baryonic states with well-defined total spins up to 7/2 and the low lying states remarkably resemble the expectations of quantum numbers from SU(6)ⓍO(3) symmetry.
One-Neutron Removal Measurement Reveals {sup 24}O as a New Doubly Magic Nucleus
Kanungo, R.; Perro, C.; Nociforo, C.; Aumann, T.; Geissel, H.; Gerl, J.; Kindler, B.; Litvinov, Y.; Lommel, B.; Mahata, K.; Scheidenberger, C.; Sun, B.; Weick, H.; Winkler, M.; Prochazka, A.; Farinon, F.; Knoebel, R.; Boutin, D.; Lenske, H.; Cortina-Gil, D.
2009-04-17
The first measurement of the momentum distribution for one-neutron removal from {sup 24}O at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99{+-}4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63{+-}7 mb. The results are well explained with a nearly pure 2s{sub 1/2} neutron spectroscopic factor of 1.74{+-}0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that {sup 24}O is a new doubly magic nucleus.
Nonparametric Inference of Doubly Stochastic Poisson Process Data via the Kernel Method.
Zhang, Tingting; Kou, S C
2010-01-01
Doubly stochastic Poisson processes, also known as the Cox processes, frequently occur in various scientific fields. In this article, motivated primarily by analyzing Cox process data in biophysics, we propose a nonparametric kernel-based inference method. We conduct a detailed study, including an asymptotic analysis, of the proposed method, and provide guidelines for its practical use, introducing a fast and stable regression method for bandwidth selection. We apply our method to real photon arrival data from recent single-molecule biophysical experiments, investigating proteins' conformational dynamics. Our result shows that conformational fluctuation is widely present in protein systems, and that the fluctuation covers a broad range of time scales, highlighting the dynamic and complex nature of proteins' structure.
Pennycuick, C.J.; Shaffner, F.C.; Fuller, M.R.; Obrecht, H.H.; Sternberg, L.
1990-01-01
Radiotracking transmitters were fitted to White-tailed Tropicbirds nesting at Culebra, Puerto Rico. Foragers were located by light aircraft out to 89 km SSW of the nesting colony, over a deep-water foraging area south of Vieques Island, Puerto Rico and west of St Croix, U. S. Virgin Islands. Two birds were followed out to 176 km NNW from the colony, over the Puerto Rico Trench, but these did not subsequently return. Foragers carrying radio transmitters performed similarly to those without, in terms of duration of absence from the colony, and mass of food brought for the chick. However, measuremetns of energy consumption by the doubly labelled water method indicated that birds with transmitters consumed significantly more energy than those without.
NASTRAN implementation of an isoparametric doubly-curved quadrilateral shell element
NASA Technical Reports Server (NTRS)
Potvin, A. B.; Leick, R. D.
1978-01-01
A quadrilateral shell element, CQUAD4, was added to level 15.5 and subsequently to level 16.0 of NASTRAN. The element exhibited doubly curved surfaces and used biquadratic interpolation functions. Reduced integration techniques were used to improve the performance of the element in thin shell problems. The creation of several new bulk data items is discussed, along with a special module, GPNORM, to process SHLNORM bulk data cards. In addition to the theoretical basis for the element stiffness matrix, consistent mass and load matrices are presented. Several potential sources of degenerate behavior of the element were investigated. Guidelines for proper use of the element were suggested. Performance of the element on several widely published classical examples was demonstrated. The results showed a significant improvement over presently available NASTRAN shell elements for even the coarsest meshes. Potential applications to two classes of practical problems are discussed.
Tsiatis, Anastasios A; Davidian, Marie; Cao, Weihua
2011-06-01
A routine challenge is that of making inference on parameters in a statistical model of interest from longitudinal data subject to dropout, which are a special case of the more general setting of monotonely coarsened data. Considerable recent attention has focused on doubly robust (DR) estimators, which in this context involve positing models for both the missingness (more generally, coarsening) mechanism and aspects of the distribution of the full data, that have the appealing property of yielding consistent inferences if only one of these models is correctly specified. DR estimators have been criticized for potentially disastrous performance when both of these models are even only mildly misspecified. We propose a DR estimator applicable in general monotone coarsening problems that achieves comparable or improved performance relative to existing DR methods, which we demonstrate via simulation studies and by application to data from an AIDS clinical trial. PMID:20731640
Fabrication and characterization of GaN nanowire doubly clamped resonators
Maliakkal, Carina B. Mathew, John P.; Hatui, Nirupam; Rahman, A. Azizur; Deshmukh, Mandar M.; Bhattacharya, Arnab
2015-09-21
Gallium nitride (GaN) nanowires (NWs) have been intensely researched as building blocks for nanoscale electronic and photonic device applications; however, the mechanical properties of GaN nanostructures have not been explored in detail. The rigidity, thermal stability, and piezoelectric properties of GaN make it an interesting candidate for nano-electromechanical systems. We have fabricated doubly clamped GaN NW electromechanical resonators on sapphire using electron beam lithography and estimated the Young's modulus of GaN from resonance frequency measurements. For wires of triangular cross section with side ∼90 nm, we obtained values for the Young's modulus to be about 218 and 691 GPa, which are of the same order of magnitude as the values reported for bulk GaN. We also discuss the role of residual strain in the nanowire on the resonant frequency and the orientation dependence of the Young's modulus in wurtzite crystals.
Electrodynamics of a generalized charged particle in doubly special relativity framework
Pramanik, Souvik; Ghosh, Subir; Pal, Probir
2014-07-15
In the present paper, dynamics of generalized charged particles are studied in the presence of external electromagnetic interactions. This particular extension of the free relativistic particle model lives in Non-Commutative κ-Minkowski space–time, compatible with Doubly Special Relativity, that is motivated to describe Quantum Gravity effects. Furthermore we have also considered the electromagnetic field to be dynamical and have derived the modified forms of Lienard–Wiechert like potentials for these extended charged particle models. In all the above cases we exploit the new and extended form of κ-Minkowski algebra where electromagnetic effects are incorporated in the lowest order, in the Dirac framework of Hamiltonian constraint analysis.
Zhou, Xiaoming; Badreddine Assouar, M. Oudich, Mourad
2014-11-21
We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of λ/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic metamaterials for ultrasonic focused imaging.
The unusual system of doubly uniparental inheritance of mtDNA: isn't one enough?
Breton, Sophie; Beaupré, Hélène Doucet; Stewart, Donald T; Hoeh, Walter R; Blier, Pierre U
2007-09-01
Mitochondria possess their own genetic material (mitochondrial DNA or mtDNA), whose gene products are involved in mitochondrial respiration and oxidative phosphorylation, transcription, and translation. In animals, mitochondrial DNA is typically transmitted to offspring by the mother alone. The discovery of 'doubly uniparental inheritance' (DUI) of mtDNA in some bivalves has challenged the paradigm of strict maternal inheritance (SMI). In this review, we survey recent advances in our understanding of DUI, which is a peculiar system of cytoplasmic DNA inheritance that involves distinct maternal and paternal routes of mtDNA transmission, a novel extension of a mitochondrial gene (cox2), recombination, and periodic 'role-reversals' of the normally male and female-transmitted mitochondrial genomes. DUI provides a unique opportunity for studying nuclear-cytoplasmic genome interactions and the evolutionary significance of different modes of mitochondrial inheritance.
Ni Dongdong; Ren Zhongzhou
2011-01-15
An extension of the generalized density-dependent cluster model (GDDCM) is presented to study {alpha}-cluster structure above doubly closed shells. In all cases, the microscopic {alpha}-core potential is numerically constructed in the double-folding model with CDM3Y6 nucleon-nucleon interactions plus proton-proton Coulomb interactions. The properties of intraband E2 transitions and {alpha} decays are calculated by the exact solution of the Schroedinger equation with appropriate boundary conditions. It is found that the enhanced B(E2) transition strengths are well reproduced without any effective charge and the calculations of {alpha}-decay properties show good agreement with the available experimental data. This indicates that the GDDCM has universal applicability and equal validity regardless of whether the {alpha}-cluster states are in light or heavy nuclei.
Grid-connected in-stream hydroelectric generation based on the doubly fed induction machine
NASA Astrophysics Data System (ADS)
Lenberg, Timothy J.
Within the United States, there is a growing demand for new environmentally friendly power generation. This has led to a surge in wind turbine development. Unfortunately, wind is not a stable prime mover, but water is. Why not apply the advances made for wind to in-stream hydroelectric generation? One important advancement is the creation of the Doubly Fed Induction Machine (DFIM). This thesis covers the application of a gearless DFIM topology for hydrokinetic generation. After providing background, this thesis presents many of the options available for the mechanical portion of the design. A mechanical turbine is then specified. Next, a method is presented for designing a DFIM including the actual design for this application. In Chapter 4, a simulation model of the system is presented, complete with a control system that maximizes power generation based on water speed. This section then goes on to present simulation results demonstrating proper operation.
Revised and extended level scheme of the doubly-odd nucleus {sup 188}Ir
Jungclaus, A.; Modamio, V.; Egido, J. L.; Fernandez, M. A.; Schwengner, R.; Algora, A.; Bazzacco, D.; Lenzi, S.; Marginean, N.; Ur, C. A.; Escrig, D.; Fraile, L. M.; Martinez, T.; Napoli, D. R.
2008-02-15
High-spin states in the doubly odd Z=77 nucleus {sup 188}Ir were studied using the reaction {sup 186}W({sup 7}Li, 5n) at 59 MeV and the GASP spectrometer for {gamma}-ray detection. The level structures recently suggested to be built on the known 4.1(3) ms isomeric state of this nucleus have been considerably revised and extended and an isomer with a lifetime of 17.7(2) ns has been identified within the main decay sequence. In addition two rotational bands built on low spin states below the ms isomer have been observed for the first time. The basic features of the excitation scheme of {sup 188}Ir are discussed within the Hartree-Fock-Bogoliubov theory within the Lipkin-Nogami approach with the finite-range density-dependent Gogny force.
Power enhancement of burst-mode UV pulses using a doubly-resonant optical cavity
Rahkman, Abdurahim; Notcutt, Mark; Liu, Yun
2015-11-24
We report a doubly-resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (IR, 1064 nm) and its frequency tripled ultraviolet (UV, 355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber optic frequency shifter. The DREC technique opens a new paradigm in the applications of optical cavities to power enhancement of burst-mode lasers with arbitrarymore » macropulse width and repetition rate.« less
Ultrafast spectroscopy of super high frequency mechanical modes of doubly clamped beams
Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S.; Grebing, Jochen; Erbe, Artur; Mounier, Denis; Gusev, Vitalyi
2013-12-02
We use ultrafast pump-probe spectroscopy to study the mechanical vibrations in the time domain of doubly clamped silicon nitride beams. Beams with two different clamping conditions are investigated. Finite element method calculations are performed to analyse the mode spectra of both structures. By calculating the strain integral on the surface of the resonators, we are able to reproduce the effect of the detection mechanism and identify all the measured modes. We show that our spectroscopy technique combined with our modelling tools allow the investigation of several different modes in the super high frequency range (3-30 GHz) and above, bringing more information about the vibration modes of nanomechanical resonators.
Doubly periodic instability pattern in a smectic-A liquid crystal
NASA Astrophysics Data System (ADS)
Manyuhina, O. V.; Tordini, G.; Bras, W.; Maan, J. C.; Christianen, P. C. M.
2013-05-01
We report the observation of a doubly periodic surface defect pattern in the liquid crystal 8CB, formed during the nematic-smectic-A phase transition. The pattern results from the antagonistic alignment of the 8CB molecules, which is homeotropic at the surface and planar in the bulk of the sample cell. Within the continuum Landau-de Gennes theory of smectic liquid crystals, we find that the long period (≈10 μm) of the pattern is given by the balance between the surface anchoring and the elastic energy of curvature wall defects. The short period (≈1 μm) we attribute to a saddle-splay distortion, leading to a nonzero Gaussian curvature and causing the curvature walls to break up.
Doubly periodic instability pattern in a smectic-A liquid crystal.
Manyuhina, O V; Tordini, G; Bras, W; Maan, J C; Christianen, P C M
2013-05-01
We report the observation of a doubly periodic surface defect pattern in the liquid crystal 8CB, formed during the nematic-smectic-A phase transition. The pattern results from the antagonistic alignment of the 8CB molecules, which is homeotropic at the surface and planar in the bulk of the sample cell. Within the continuum Landau-de Gennes theory of smectic liquid crystals, we find that the long period (≈10 μm) of the pattern is given by the balance between the surface anchoring and the elastic energy of curvature wall defects. The short period (≈1 μm) we attribute to a saddle-splay distortion, leading to a nonzero Gaussian curvature and causing the curvature walls to break up. PMID:23767471
'Doubly Magic' Conditions in Magic-Wavelength Trapping of Ultracold Alkali-Metal Atoms
Derevianko, Andrei
2010-07-16
In experiments with trapped atoms, atomic energy levels are shifted by the trapping optical and magnetic fields. Regardless of this strong perturbation, precision spectroscopy may be still carried out using specially crafted, 'magic' trapping fields. Finding these conditions for particularly valuable microwave transitions in alkali-metal atoms has so far remained an open challenge. Here I demonstrate that the microwave transitions in alkali-metal atoms may be indeed made impervious to both trapping laser intensity and fluctuations of magnetic fields. I consider driving multiphoton transitions between the clock levels and show that these 'doubly magic' conditions are realized at special values of trapping laser wavelengths and fixed values of relatively weak magnetic fields. This finding has implications for precision measurements and quantum information processing with qubits stored in hyperfine manifolds.
NASA Astrophysics Data System (ADS)
Hyodo, Tetsuo; Liu, Yan-Rui; Oka, Makoto; Sudoh, Kazutaka; Yasui, Shigehiro
2013-04-01
Structure and production of doubly charmed tetraquarks Tcc (cc ubardbar) are studied from the viewpoint of color configurations. Based on the diquark correlation, the tetraquark Tcc with I (JP) = 0 (1+) is considered to be stable against strong decay. We discuss that the mixing probability of color antitriplet and sextet cc components in Tcc is suppressed by 1 / mc2, so the two configurations are separately realized in the heavy quark limit. Utilizing the nonrelativistic QCD framework, we evaluate the production cross sections of Tcc in electron-positron collisions. The momentum dependence of the cross section of color antitriplet is found to be different from that of sextet, which can be used to discriminate the color structure of the Tcc states in experimental measurements.
Jia Xiangfu; Sun Shiyan
2011-03-15
A dynamically screened three-Coulomb-wave model (DS3C) is applied to study the single ionization of sodium by electron impact. Triply differential cross sections (TDCS) are calculated in doubly symmetric geometry at excess energies of 6, 10, 15, 20, 30, 40, 50, and 60 eV. Comparisons are made among DS3C and the latest experimental data and such theoretical predictions as the three-Coulomb-wave function approach, the distorted-wave Born approximation, and the nonperturbative convergent close-coupling method. The angular distribution and relative magnitude of the present TDCS are found to qualitatively reproduce the reported experimental data. It is shown that dynamically screened effects are important in the geometries studied here.
Atomic mass measurements of short-lived nuclides around the doubly-magic 208Pb
NASA Astrophysics Data System (ADS)
Weber, C.; Audi, G.; Beck, D.; Blaum, K.; Bollen, G.; Herfurth, F.; Kellerbauer, A.; Kluge, H.-J.; Lunney, D.; Schwarz, S.
2008-04-01
Accurate atomic mass measurements of neutron-deficient and neutron-rich nuclides around the doubly-magic 208Pb and of neutron-rich cesium isotopes were performed with the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The masses of 145,147Cs, 181,183Tl, 186Tl m, 187Tl m, 196Tl m, 205Tl, 197Pb m, 208Pb, 190-197Bi, 209,215,216Bi, 203,205,229Fr, and 214,229,230Ra were determined. The obtained relative mass uncertainty in the range of 2×10 to 2×10 is not only required for safe identification of isomeric states but also allows mapping the detailed structure of the mass surface. A mass adjustment procedure was carried out and the results included into the Atomic Mass Evaluation. The resulting separation energies are discussed and the mass spectrometric and laser spectroscopic data are examined for possible correlations.
Fabrication and characterization of GaN nanowire doubly clamped resonators
NASA Astrophysics Data System (ADS)
Maliakkal, Carina B.; Mathew, John P.; Hatui, Nirupam; Rahman, A. Azizur; Deshmukh, Mandar M.; Bhattacharya, Arnab
2015-09-01
Gallium nitride (GaN) nanowires (NWs) have been intensely researched as building blocks for nanoscale electronic and photonic device applications; however, the mechanical properties of GaN nanostructures have not been explored in detail. The rigidity, thermal stability, and piezoelectric properties of GaN make it an interesting candidate for nano-electromechanical systems. We have fabricated doubly clamped GaN NW electromechanical resonators on sapphire using electron beam lithography and estimated the Young's modulus of GaN from resonance frequency measurements. For wires of triangular cross section with side ˜90 nm, we obtained values for the Young's modulus to be about 218 and 691 GPa, which are of the same order of magnitude as the values reported for bulk GaN. We also discuss the role of residual strain in the nanowire on the resonant frequency and the orientation dependence of the Young's modulus in wurtzite crystals.
A Study for Doubly-Charged Higgs Boson at the Tevatron
Baroiant, Sasha
2006-01-01
We search for the pair production of doubly charged Higgs particles followed by the lepton-flavor violating decay of each Higgs into electron-and-tau and muonand- tau pairs using 350 pb^{-1} of data collected by the CDF II experiment at the Fermilab Tevatron. Separate searches investigate cases where three or four finalstate leptons are detected, and the limits for each exclusive decay mode reflect the combined results of both searches. Assuming the H$±±\\atop{L}$ decays exclusively into likesign electron-and-tau pairs, we set a lower limit on its mass of 114 GeV/c^{2} at the 95 % confidence level. In the case of exclusive muon-and-tau decays, we set a lower mass limit of 112 GeV/c^{2} also at the 95% confidence level.
Long-range spoof surface plasmons on the doubly corrugated metal surfaces
NASA Astrophysics Data System (ADS)
Liu, Yong-Qiang; Kong, Ling-Bao; Liu, Pu-Kun
2016-07-01
In this paper, symmetric spoof surface plasmon (SSP) mode on the doubly corrugated metal surfaces is indentified as long-range spoof surface plasmon (LRSSP) because of its extreme low propagation loss and symmetric dominant field profile so as short-range SSP (SRSSP) for anti-symmetric mode. Based on theoretical calculation and numerical simulation of finite integration method, symmetric and anti-symmetric SSP modes with various gap sizes between these two identical corrugated metal surfaces are investigated in terahertz (THz) regime and good agreement is realized. Besides, the low loss superiority of LRSSP diminishes along with the increased gap size. This work opens up new avenues to utilize this long-range surface mode in far-infrared, THz or lower frequency band and can find many potential applications such as low-loss waveguide, filters and novel electronic sources.
Sympathetic cooling of laser-produced doubly charged ions in a few-ion crystal
Kwapien, T.; Eichmann, U.; Sandner, W.
2007-06-15
We present experimental results in which single Ca{sup +} ions in a chain of laser cooled Ca{sup +} ions are further ionized by means of an intense short pulse laser. The ions are trapped in a linear Paul trap, which is instantaneously loaded by ions from a laser-produced ablation plasma. Due to sympathetic cooling the doubly charged ions are held in place. We study and characterize linear few-ion crystals with mixed charges by applying a radio frequency field, which excites the center of mass (c.m.) and breathing modes of different configurations. From the position shift of laser cooled ions initiated through the higher charge state we can deduce the charge of the nonfluorescing ion. This information might be used as an intensity probe for high intensity lasers.
Search for doubly-charged Higgs bosons through the diboson decay channel at the ILC
NASA Astrophysics Data System (ADS)
Cao, Jun; Liu, Yao-Bei
2016-09-01
The doubly-charged Higgs bosons (H5±±) are the typical particles predicted in the Georgi-Machacek (GM) model and their decay modes depend on the magnitude of the triplet vacuum expectation value (VEV) vΔ. In this paper, we focus on the study of their pair production process at the International Linear Collider (ILC): e+e‑→ H 5++H 5‑‑→ W+W+W‑W‑→ ℓ‑ℓ‑jjjjE/ Tmiss, with the subsequent decay of two like-sign W bosons through a pair of like-sign dileptons and the remaining two in their hadronic decays. The 5σ confidence level discovery reach at the ILC is also studied with two collision energies of 1.0 TeV and 1.5 TeV.
NASA Astrophysics Data System (ADS)
Yin, X. W.; Gu, X. J.; Cui, H. F.; Shen, R. Y.
2007-10-01
Acoustic radiation from a point-driven, infinite fluid-loaded, laminated composite plate which is reinforced by doubly periodic parallel stiffeners is investigated theoretically. The stiffeners interact with the plate only through normal forces. Fourier transform is used for solving the responses of the plate, and the stationary phase approximate is then employed to find an expression for the far field pressure. Acoustic radiation from a stiffened uniform plate composed of multiple isotropic layers is calculated with the present stiffened, laminated composite plate theory, and with the stiffened uniform isotropic plate theory that Mace has proposed. Comparison of the numerical results reveals the validity of our work. Characteristics of the acoustic radiation from a stiffened laminated composite plate are examined through examples and some physical interpretations of significant features are also offered.
Modular invariant partition functions for the doubly extended N = 4 superconformal algebras
NASA Astrophysics Data System (ADS)
Ooguri, Hirosi; Petersen, Jens Lyng; Taormina, Anne
1992-01-01
Non-trivial modular properties of characters of the doubly extended N = 4 superconformal algebras Aγ, Ãγ are derived from two different points of view. First, we use realizations on Wolf spaces, in particular when one of the levels of the two commuting affine SU(2) subalgebras takes the value 2. We emphasize how these realizations involve rational torus theories, and how some specific combinations of massless characters transform under the modular group as affine SU(2) characters. Second, we show how these combinations, and generalizations thereof, emerge from a study of the explicit form of the characters when angular variables are partly restricted, but the levels are not. The two results are then combined to give stringent constraints on the modular invariant Ãγ partition functions and they give rise to a partial classification of the latter, closely related to that of affine SU(2).
Nonlinear thermocurrent beam instability of a weakly ionized plasma
Hatami, M. M.; Niknam, A. R.; Shokri, B.; Rukhadze, A. A.
2008-02-15
The boundaries of the thermocurrent instability in the linear theory and its maximum development increment are determined. It is shown that the group velocity in this instability depends on the wave vector giving rise to the modulational instability. Then the theory of the thermocurrent instability is considered in the nonlinear regime. In the nonlinear regime, the one-dimensional theory of the thermocurrent instability shows that the instability is caused by negative diffusion in a dense quasineutral plasma under the condition of nonresonant Cerenkov radiation. In this case, plasma diffuses from the rarefied region to the dense region until density falls down so that the quasineutrality condition would be violated and thus diffusion again would become positive. In conclusion, a longitudinal periodic nonlinear structure with a specific parameter is formed in the plasma.
National Institute of Standards and Technology Data Gateway
NIST Diffusion Data Center (Web, free access) The NIST Diffusion Data Center is a collection of over 14,100 international papers, theses, and government reports on diffusion published before 1980.
Parallel flow diffusion battery
Yeh, H.C.; Cheng, Y.S.
1984-01-01
A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.
Parallel flow diffusion battery
Yeh, Hsu-Chi; Cheng, Yung-Sung
1984-08-07
A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.
Cosmological baryon diffusion and nucleosynthesis
NASA Astrophysics Data System (ADS)
Applegate, James H.; Hogan, Craig J.; Scherrer, Robert J.
1987-02-01
The diffusion rate of baryons through the big-bang plasma is calculated. Fluctuations in baryon density in the early Universe lead to inhomogeneities in the neutron-proton ratio, due to the differential diffusion of these particles through the radiation plasma. For certain types of nonlinear fluctuations, some nucleosynthesis would occur in very neutron-rich regions. Nuclear products of homogeneous neutron-enriched regions are evaluated numerically using a standard reaction network and these results are used to estimate final abundances in an inhomogeneous universe. Net deuterium and lithium abundances tend to increase and the net helium abundance tends to decrease compared to an unperturbed standard model. It is suggested that pronounced nonlinear baryon-density fluctuations produced in QCD- or electroweak-epoch phase transitions could alter abundances sufficiently to make a closed baryonic universe consistent with current observations of these elements. In such a model the abundance of heavier elements (C,N,O, etc.) increases significantly and approaches observable levels. Abundances can be used to place constraints on extreme scenarios for phase transitions at these epochs.
Radiative Rates for Forbidden Transitions in Doubly-Ionized Fe-Peak Elements
NASA Astrophysics Data System (ADS)
Fivet, Vanessa; Quinet, P.; Bautista, M.
2012-05-01
Accurate and reliable atomic data for lowly-ionized Fe-peak species (Sc, Ti, V, Cr, Mn, Fe, Co, Ni and Cu) are of paramount importance for the analysis of the high resolution astrophysical spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources like Herbig-Haro objects in the Orion Nebula [1] and stars like Eta Carinae [2]. However, forbidden transitions between low-lying metastable levels of doubly-ionized iron-peak ions have been very little investigated so far and radiative rates for those lines remain sparse or inexistent. We are carrying out a systematic study of the electronic structure of doubly-ionized iron-peak elements. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities are computed using the pseudo-relativistic Hartree-Fock (HFR) code of Cowan [3] and the central Thomas-Fermi-Dirac potential approximation implemented in AUTOSTRUCTURE [4]. This multi-platform approach allows for consistency checks and intercomparison and has proven very successful in the study of the complex Fe-peak species where many different effects contribute [5]. References [1] A. Mesa-Delgado et al., MNRAS 395 (2009) 855 [2] S. Johansson et al., A&A 361 (2000) 977 [3] R.D. Cowan, The Theory of Atomic Structure and Spectra, Berkeley: Univ. California Press (1981) [4] N.R. Badnell, J. Phys. B: At. Mol. Opt. Phys. 30 (1997) 1 [5] M. Bautista et al., ApJ 718 (2010) L189
Energy expenditure by doubly labeled water: validation in humans and proposed calculation
Schoeller, D.A.; Ravussin, E.; Schutz, Y.; Acheson, K.J.; Baertschi, P.; Jequier, E.
1986-05-01
To further validate the doubly labeled water method for measurement of CO/sub 2/ production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received /sup 2/H/sub 2/(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial /sup 2/H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO/sub 2/ production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for /sup 2/H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.
Spoof surface plasmon modes on doubly corrugated metal surfaces at terahertz frequencies
NASA Astrophysics Data System (ADS)
Liu, Yong-Qiang; Kong, Ling-Bao; Du, Chao-Hai; Liu, Pu-Kun
2016-06-01
Spoof surface plasmons (SSPs) have many potential applications such as imaging and sensing, communications, innovative leaky wave antenna and many other passive devices in the microwave and terahertz (THz) spectrum. The extraordinary properties of SSPs (e.g. extremely strong near field, enhanced beam–wave interaction) make them especially attractive for developing novel THz electronic sources. SSP modes on doubly corrugated metal surfaces are investigated and analyzed both theoretically and numerically in this paper. The analytical SSP dispersion expressions of symmetric and anti-symmetric modes are obtained with a simplified modal field expansion method; the results are also verified by the finite integration method. Additionally, the propagation losses are also considered for real copper surfaces with a limited constant conductivity in a THz regime. It is shown that the asymptotical frequency of the symmetric mode at the Brillouin boundary decreases along with the decreased gap size between these two corrugated metal surfaces while the asymptotical frequency increases for the anti-symmetric mode. The anti-symmetric mode demonstrates larger propagation losses than the symmetric mode. Further, the losses for both symmetric and anti-symmetric modes decrease when this gap size enlarges. By decreasing groove depth, the asymptotical frequency increases for both the symmetric and the anti-symmetric mode, but the variation of propagation losses is more complicated. Propagation losses increase along with the increased period. Our studies on the dispersion characteristics and propagation losses of SSP modes on this doubly corrugated metallic structure with various parameters is instructive for numerous applications such as waveguides, circuitry systems with high integration, filters and powerful electronic sources in the THz regime.
Diffusing Diffusivity: A Model for Anomalous, yet Brownian, Diffusion
NASA Astrophysics Data System (ADS)
Chubynsky, Mykyta V.; Slater, Gary W.
2014-08-01
Wang et al. [Proc. Natl. Acad. Sci. U.S.A. 106, 15160 (2009)] have found that in several systems the linear time dependence of the mean-square displacement (MSD) of diffusing colloidal particles, typical of normal diffusion, is accompanied by a non-Gaussian displacement distribution G(x ,t), with roughly exponential tails at short times, a situation they termed "anomalous yet Brownian" diffusion. The diversity of systems in which this is observed calls for a generic model. We present such a model where there is diffusivity memory but no direction memory in the particle trajectory, and we show that it leads to both a linear MSD and a non-Gaussian G(x ,t) at short times. In our model, the diffusivity is undergoing a (perhaps biased) random walk, hence the expression "diffusing diffusivity". G(x ,t) is predicted to be exactly exponential at short times if the distribution of diffusivities is itself exponential, but an exponential remains a good fit for a variety of diffusivity distributions. Moreover, our generic model can be modified to produce subdiffusion.
A Relation for Nanodroplet Diffusion on Smooth Surfaces
Li, Chu; Huang, Jizu; Li, Zhigang
2016-01-01
In this work, we study the diffusion of nanodroplets on smooth surfaces through molecular dynamics (MD) simulations and theoretical analyses. Molecular dynamics simulations show that nanodroplet surface diffusion is different from that of single molecules and solid particles. The dependence of nanodroplet diffusion coefficient on temperature undergoes a transition from linear to nonlinear as the surface wettability is weakened due to the coupling of temperature and surface energy. We also develop a simple relation for the diffusion coefficient by using the contact angle and contact radius of the droplet. It works well for a wide range of surface wettabilities and different sized nanodroplets, as confirmed by MD simulations. PMID:27215471
NASA Astrophysics Data System (ADS)
Hausmann, B. J. M.; Bulu, I.; Venkataraman, V.; Deotare, P.; Lončar, M.
2014-05-01
Despite progress towards integrated diamond photonics, studies of optical nonlinearities in diamond have been limited to Raman scattering in bulk samples. Diamond nonlinear photonics, however, could enable efficient, in situ frequency conversion of single photons emitted by diamond's colour centres, as well as stable and high-power frequency microcombs operating at new wavelengths. Both of these applications depend crucially on efficient four-wave mixing processes enabled by diamond's third-order nonlinearity. Here, we have realized a diamond nonlinear photonics platform by demonstrating optical parametric oscillation via four-wave mixing using single-crystal ultrahigh-quality-factor (1 × 106) diamond ring resonators operating at telecom wavelengths. Threshold powers as low as 20 mW are measured, and up to 20 new wavelengths are generated from a single-frequency pump laser. We also report the first measurement of the nonlinear refractive index due to the third-order nonlinearity in diamond at telecom wavelengths.
Nonlinear rotordynamics analysis
NASA Technical Reports Server (NTRS)
Day, W. B.
1985-01-01
The special nonlinearities of the Jeffcott equations in rotordynamics are examined. The immediate application of this analysis is directed toward understanding the excessive vibrations recorded in the LOX pump of the SSME during hot firing ground testing. Deadband, side force and rubbing are three possible sources of inducing nonlinearity in the Jeffcott equations. The present analysis initially reduces these problems to the same mathematical description. A special frequency, named the nonlinear natural frequency is defined and used to develop the solutions of the nonlinear Jeffcott equations as asympotic expansions. This nonlinear natural frequency which is the ratio of the cross-stiffness and the damping, plays a major role in determining response frequencies. Numerical solutions are included for comparison with the analysis. Also, nonlinear frequency-response tables are made for a typical range of values.
Stationary nonlinear Airy beams
Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.
2011-08-15
We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.
Non-Linear Dynamics and Emergence in Laboratory Fusion Plasmas
Hnat, B.
2011-09-22
Turbulent behaviour of laboratory fusion plasma system is modelled using extended Hasegawa-Wakatani equations. The model is solved numerically using finite difference techniques. We discuss non-linear effects in such a system in the presence of the micro-instabilities, specifically a drift wave instability. We explore particle dynamics in different range of parameters and show that the transport changes from diffusive to non-diffusive when large directional flows are developed.
Nonlinear degradation-enhanced transport of morphogens performing subdiffusion.
Fedotov, Sergei; Falconer, Steven
2014-01-01
We study a morphogen gradient formation under nonlinear degradation and subdiffusive transport. In the long-time limit, we obtain the nonlinear effect of degradation-enhanced diffusion, resulting from the interaction of non-Markovian subdiffusive transport with a nonlinear reaction. We find the stationary profile of power-law type, which has implications for robustness, with the shape of the profile being controlled by the anomalous exponent. Far away from the source of morphogens, any changes in the rate of production are not felt.
Nonlinear evolution of the unmagnetized ion Rayleigh--Taylor instability
Hassam, A.B.; Huba, J.D. )
1990-09-01
The nonlinear evolution of the unmagnetized ion Rayleigh--Taylor instability is investigated. A nonlinear state corresponding to localized clumps of high-density plasma is obtained analytically. The characteristic scale size of the clumps is given by {Delta}{similar to}{ital D}({ital gL}{sub {ital n}}){sup {minus}1/2}, where {ital g} is the gravitational acceleration, {ital L}{sub {ital n}} is the density gradient scale length, and {ital D} is a diffusion coefficient associated with the short-scale dissipation processes in the system. It is shown numerically that this nonlinear state may be both accessible and stable.
Complex {PT}-symmetric extensions of the nonlinear ultra-short light pulse model
NASA Astrophysics Data System (ADS)
Yan, Zhenya
2012-11-01
The short pulse equation u_{xt}=u+\\frac{1}{2}(u^2u_x)_x is PT symmetric, which arises in nonlinear optics for the ultra-short pulse case. We present a family of new complex PT-symmetric extensions of the short pulse equation, i[(iu_x)^{\\sigma }]_t=au+bu^m+ic[u^n(iu_x)^{\\epsilon }]_x \\,\\, (\\sigma ,\\, \\epsilon ,\\,a,\\,b,\\,c,\\,m,\\,n \\in {R}), based on the complex PT-symmetric extension principle. Some properties of these equations with some chosen parameters are studied including the Hamiltonian structures and exact solutions such as solitary wave solutions, doubly periodic wave solutions and compacton solutions. Our results may be useful to understand complex PT-symmetric nonlinear physical models. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.
Organic nonlinear optical materials
NASA Technical Reports Server (NTRS)
Umegaki, S.
1987-01-01
Recently, it became clear that organic compounds with delocalized pi electrons show a great nonlinear optical response. Especially, secondary nonlinear optical constants of more than 2 digits were often seen in the molecular level compared to the existing inorganic crystals such as LiNbO3. The crystallization was continuously tried. Organic nonlinear optical crystals have a new future as materials for use in the applied physics such as photomodulation, optical frequency transformation, opto-bistabilization, and phase conjugation optics. Organic nonlinear optical materials, e.g., urea, O2NC6H4NH2, I, II, are reviewed with 50 references.
Nonlinear optics at interfaces
Chen, C.K.
1980-12-01
Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory.
Nonlinear Dynamics of Single Bunch Instability
Stupakov, G.V.; Breizman, B.N.; Pekker, M.S.; /Texas U.
2011-09-09
A nonlinear equation is derived that governs the evolution of the amplitude of unstable oscillations with account of quantum diffusion effects due to the synchrotron radiation. Numerical solutions to this equation predict a variety of possible scenarios of nonlinear evolution of the instability some of which are in good qualitative agreement with experimental observations. Microwave single bunch instability in circular accelerators has been observed in many machines. The instability usually arises when the number of particles in the bunch exceeds some critical value, Nc, which varies depending on the parameters of the accelerating regime. Recent observations on the SLC damping rings at SLAC with a new low-impedance vacuum chamber revealed new interesting features of the instability. In some cases, after initial exponential growth, the instability eventually saturated at a level that remained constant through the accumulation cycle. In other regimes, relaxation-type oscillations were measured in nonlinear phase of the instability. In many cases, the instability was characterized by a frequency close to the second harmonic of the synchrotron oscillations. Several attempts have been made to address the nonlinear stage of the instability based on either computer simulations or some specific assumptions regarding the structure of the unstable mode. An attempt of a more general consideration of the problem is carried out in this paper. We adopt an approach recently developed in plasma physics for analysis of nonlinear behavior of weakly unstable modes in dynamic systems. Assuming that the growth rate of the instability is much smaller than its frequency, we find a time dependent solution to Vlasov equation and derive an equation for the complex amplitude of the oscillations valid in the nonlinear regime. Numerical solutions to this equation predict a variety of possible scenarios of nonlinear evolution of the instability some of which are in good qualitative agreement
Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Aoki, M; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Borissov, G; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Carvalho, W; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K; Chan, K M; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Kajfasz, E; Kalinin, A M; Kalk, J M; Kappler, S; Karmanov, D; Kasper, P A; Katsanos, I; Kau, D; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Korablev, V M; Kozelov, A V; Kraus, J; Krop, D; Kuhl, T; Kumar, A; Kupco, A; Kurca, T; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lebrun, P; Lee, W M; Leflat, A; Lellouch, J; Leveque, J; Li, J; Li, L; Li, Q Z; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna, R; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nogima, H; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osman, N; Osta, J; Otec, R; Otero y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perfilov, M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Polozov, P; Pope, B G; Popov, A V; Potter, C; da Silva, W L Prado; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rich, P; Rieger, J; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Rominsky, M; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, E; Strauss, M; Ströhmer, R; Strom, D; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Tamburello, P; Tanasijczuk, A; Taylor, W; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Toole, T; Torchiani, I; Trefzger, T; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; van den Berg, P J; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Vokac, P; Von Toerne, E; Voutilainen, M; Wagner, R; Wahl, H D; Wang, L; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Welty-Rieger, L; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zatserklyaniy, A; Zeitnitz, C; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G
2008-08-15
We report the results of a search for pair production of doubly charged Higgs bosons via pp over-->H++H - - X-->mu+ mu+ mu- mu- X at sqrt s=1.96 TeV. We use a data set corresponding to an integrated luminosity of 1.1 fb(-1) collected from 2002 to 2006 by the D0 detector at the Fermilab Tevatron Collider. In the absence of an excess above the standard model background, lower mass limits of M(H L +/- +/-) >150 GeV/c2 and M(H R+/- +/-) >127 GeV/c2 at 95% C.L. are set, respectively, for left-handed and right-handed doubly charged Higgs bosons assuming a 100% branching ratio into muons. PMID:18764523
Odagiri, Takeshi; Kumagai, Yoshiaki; Nakano, Motoyoshi; Tanabe, Takehiko; Kitajima, Masashi; Kouchi, Noriyuki; Suzuki, Isao H.
2011-11-15
The cross sections for the formation of the metastable atomic hydrogen in the 2s state in photoexcitation of H{sub 2} and D{sub 2} were measured as a function of the incident photon energy in the range of the doubly excited states with their symmetries of the electronic states, {sup 1}{Sigma}{sub u}{sup +} or {sup 1}{Pi}{sub u}, being resolved. It has turned out from the comparison with the cross-section curves for other dissociation processes and the theoretical calculation [J. D. Bozek et al., J. Phys. B 39, 4871 (2006)] that the Q{sub 2}{sup 1}{Pi}{sub u}(1) doubly excited state of H{sub 2} dissociates into both H(2s) + H(2p) and H(2p) + H(2p). The dissociation dynamics of this state has been discussed in terms of the nonadiabatic transition during neutral dissociations.
Validation of a non-invasive blood-sampling technique for doubly-labelled water experiments.
Voigt, Christian C; Helversen, Otto Von; Michener, Robert H; Kunz, Thomas H
2003-04-01
Two techniques for bleeding small mammals have been used in doubly-labeled water (DLW) studies, including vena puncture and the use of starved nymphal stages of hematophagous reduviid bugs (Reduviidae, Hemiptera). In this study, we tested the validity of using reduviid bugs in doubly-labeled water experiments. We found that the isotope enrichment in initial blood samples collected with bugs was significantly lower compared to isotope enrichment in blood samples obtained using vena puncture. We therefore used the desiccation method for estimating total body water (TBW) in DLW experiments because TBW calculated using the isotope dilution method was overestimated when blood samples were collected using reduviid bugs. In our validation experiment with nectar-feeding bats (Glossophaga soricina), we compared estimates of daily energy expenditure (DEE) using DLW with those derived from the energy balance method. We considered Speakman's equation (controlling for 25% fractionated water loss) as the most appropriate for our study animal and calculated DEE accordingly. On average, DEE estimated with DLW was not significantly different from the mean value obtained with the energy balance method (mean deviation 1.2%). We conclude that although bug hemolymph or intestinal liquids most likely contaminate the samples, estimates of DEE are still valid because the DLW method does not depend on absolute isotope enrichments but on the rate of isotope decrease over time. However, dilution of blood with intestinal liquids or hemolymph from a bug may lead to larger variation in DEE estimates. We also tested how the relative error of DLW estimates changed with varying assumptions about fractionation. We used three additional equations for calculating DEE in DLW experiments. The basic equation for DLW experiments published by Lifson and McClintock (LM-6) assumes no fractionation, resulted in an overestimate of DEE by 10%. Nagy's equation (N-2) controls for changes in body mass but not for
The Rotational Spectrum of Singly and Doubly 13C-SUBSTITUTED Dimethylether
NASA Astrophysics Data System (ADS)
Koerber, Monika; Endres, Christian P.; Lewen, Frank; Giesen, Thomas F.; Schlemmer, Stephan; Pohl, Roland; Klein, Axel
2010-06-01
Dimethylether (DME) is a nearly prolate asymmetric top with two internal rotors (methyl groups) which undergo periodic large amplitude motions and show a complicated torsional splitting of each rotational energy level. Due to its complex spectrum and its high abundance in hot cores such as Orion KL or Sagittarius B2 at temperatures exceeding 100 K, DME is very prominent in astronomical line surveys and contributes to spectral line confusion of such sources. The interpretation of astronomical observations therefore depends on the knowledge of accurate rest frequencies and reliable intensities. Precise predictions for the ground state of DME's main isotopologue are now available up to 2.1 THz In contrast, very little is known about 13C-substituted DME. Only a few data are available on singly 13C-substituted DME, 12CH_3O13CH_3. However, no data are available on doubly 13C-substituted DME, (13CH_3)_2O, yet. While in (13CH_3)_2O the two internal rotating methyl groups are equivalent and the splitting of rotational energy levels into four substates is comparable to the main isotopologue, singly 13C-substituted DME has two non-equivalent internal rotors resulting in torsional splitting of rotational energy levels into five substates. The purpose of our new laboratory measurements is to extend the knowledge on the astrophysically relevant species 12CH_3O13CH_3. To analyze the complicated spectrum resulting from a 13C-enriched sample of DME, containing all different 13C-substituted species as well as the main isotopologue, also precise data on doubly 13C-substituted DME are inevitable. We performed measurements in the frequency region 35-120 GHz using an all solid state spectrometer. Rotational as well as torsional parameters have been obtained for (13CH_3)_2O as well as 12CH_3O13CH_3 by fitting the assigned transitions to an effective rotational Hamiltonian introduced by Peter Groner. C. Comito et al., Astrophys. J. Suppl. Ser. 156, 127-167 (2005) C. P. Endres et al
Diffusion Acceleration Schemes for Self-Adjoint Angular Flux Formulation with a Void Treatment
Yaqi Wang; Hongbin Zhang; Richard C. Martineau
2014-02-01
A Galerkin weak form for the monoenergetic neutron transport equation with a continuous finite element method and discrete ordinate method is developed based on self-adjoint angular flux formulation. This weak form is modified for treating void regions. A consistent diffusion scheme is developed with projection. Correction terms of the diffusion scheme are derived to reproduce the transport scalar flux. A source iteration that decouples the solution of all directions with both linear and nonlinear diffusion accelerations is developed and demonstrated. One-dimensional Fourier analysis is conducted to demonstrate the stability of the linear and nonlinear diffusion accelerations. Numerical results of these schemes are presented.
Kroemer, H.
1981-06-15
The dissipation processes by which electrons and holes lose energy after being trapped in quantum wells might, in a sufficiently heavily pumped quantum well laser, lead to the buildup of such a high phonon population that phonon-assisted laser action by doubly stimulated emission of photons and phonons acquires a higher gain than unassisted laser action. The resulting mode switching exhibits a pronounced hysteresis with pump rate, which should be a characteristic identifying feature of phonon-assisted laser action.
Lifetime measurements using the CLARA-PRISMA setup around the {sup 48}Ca doubly-magic nucleus
Valiente-Dobon, J. J.; Gadea, A.; Stefanini, A. M.; Corradi, L.; De Angelis, G.; Fioretto, E.; Grodner, E.; Mason, P.; Napoli, D. R.; Recchia, F.; Sahin, E.; Mengoni, D.; Farnea, E.; Bazzacco, D.; Montagnoli, G.; Ur, C. A.; Lenzi, S. M.; Lunardi, S.; Scarlassara, F.; Dewald, A.
2008-11-11
The lifetimes of the first excited states of nuclei around the doubly-magic nucleus {sup 48}Ca have been determined using a novel method that combines the Recoil Distance Doppler Shift (RDDS) method with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This novel method and some preliminary results on lifetimes are presented.
NASA Astrophysics Data System (ADS)
Petersen, Jens Lyng; Taormina, Anne
1991-05-01
The doubly extended N = 4 superconformal algebra, which contains all conventional extended superconformal algebras, is analyzed when one of the central extensions is set to 1. The modular transformations of the characters are derived, the relation between the characters and those of the N = 2 minimal is clarified, and in the process it is shown how rather simple extensions of the algebra based on rational torus theories, give rise to finite dimensional representations of the modular group.
Nonlinear Optics and Applications
NASA Technical Reports Server (NTRS)
Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)
2007-01-01
Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.
Nonlinearly realized extended supergravity
Izawa, K.-I.; Nakai, Y.; Takahashi, Ryo
2010-10-01
We provide a nonlinear realization of supergravity with an arbitrary number of supersymmetries by means of coset construction. The number of gravitino degrees of freedom counts the number of supersymmetries, which will possibly be probed in future experiments. We also consider Goldstino embedding in the construction to discuss the relation to nonlinear realizations with rigid supersymmetries.
Friction and nonlinear dynamics
NASA Astrophysics Data System (ADS)
Manini, N.; Braun, O. M.; Tosatti, E.; Guerra, R.; Vanossi, A.
2016-07-01
The nonlinear dynamics associated with sliding friction forms a broad interdisciplinary research field that involves complex dynamical processes and patterns covering a broad range of time and length scales. Progress in experimental techniques and computational resources has stimulated the development of more refined and accurate mathematical and numerical models, capable of capturing many of the essentially nonlinear phenomena involved in friction.
NASA Technical Reports Server (NTRS)
Sheen, Jyh-Jong; Bishop, Robert H.
1992-01-01
The feedback linearization technique is applied to the problem of spacecraft attitude control and momentum management with control moment gyros (CMGs). The feedback linearization consists of a coordinate transformation, which transforms the system to a companion form, and a nonlinear feedback control law to cancel the nonlinear dynamics resulting in a linear equivalent model. Pole placement techniques are then used to place the closed-loop poles. The coordinate transformation proposed here evolves from three output functions of relative degree four, three, and two, respectively. The nonlinear feedback control law is presented. Stability in a neighborhood of a controllable torque equilibrium attitude (TEA) is guaranteed and this fact is demonstrated by the simulation results. An investigation of the nonlinear control law shows that singularities exist in the state space outside the neighborhood of the controllable TEA. The nonlinear control law is simplified by a standard linearization technique and it is shown that the linearized nonlinear controller provides a natural way to select control gains for the multiple-input, multiple-output system. Simulation results using the linearized nonlinear controller show good performance relative to the nonlinear controller in the neighborhood of the TEA.
Lasers for nonlinear microscopy.
Wise, Frank
2013-03-01
Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.
NASA Astrophysics Data System (ADS)
Saha Ray, S.
2016-09-01
In this article, the Jacobi elliptic function method viz. the mixed dn-sn method has been presented for finding the travelling wave solutions of the Davey-Stewartson equations. As a result, some solitary wave solutions and doubly periodic solutions are obtained in terms of Jacobi elliptic functions. Moreover, solitary wave solutions are obtained as simple limits of doubly periodic functions. These solutions can be useful to explain some physical phenomena, viz. evolution of a three-dimensional wave packet on water of finite depth. The proposed Jacobi elliptic function method is efficient, powerful and can be used in order to establish newer exact solutions for other kinds of nonlinear fractional partial differential equations arising in mathematical physics.
Perpendicular diffusion of energetic particles in noisy reduced magnetohydrodynamic turbulence
Shalchi, A.; Hussein, M. E-mail: m_hussein@physics.umanitoba.ca
2014-10-10
A model for noisy reduced magnetohydrodynamic turbulence was recently proposed. This model was already used to study the random walk of magnetic field lines. In the current article we use the same model to investigate the diffusion of energetic particles across the mean magnetic field. To compute the perpendicular diffusion coefficient, two analytical theories are used, namely, the Non-Linear Guiding Center theory and the Unified Non-Linear Transport (UNLT) theory. It is shown that the two theories provide different results for the perpendicular diffusion coefficient. We also perform test-particle simulations for the aforementioned turbulence model. We show that only the UNLT theory describes perpendicular transport accurately, confirming that this is a powerful tool in diffusion theory.
NASA Astrophysics Data System (ADS)
Yang, Z. Q.; Ye, D. F.; Ding, Thomas; Pfeifer, Thomas; Fu, L. B.
2015-01-01
In the present paper, we investigate the time-resolved transient absorption spectroscopy of doubly excited states of helium atoms by solving the time-dependent two-electron Schrödinger equation numerically based on a one-dimensional model. The helium atoms are subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser pulse. A superposition of doubly excited states populated by the XUV pulse is identified, which interferes with the direct ionization pathway leading to Fano resonance profiles in the photoabsorption spectrum. In the presence of an IR laser, however, the Fano line profiles are strongly modified: A shifting, splitting, and broadening of the original absorption lines is observed when the XUV attosecond pulse and infrared few-cycle laser pulse overlap in time, which is in good agreement with recent experimental results. At certain time delays, we observe symmetric Lorentz, inverted Fano profiles, and even negative absorption cross sections indicating that the XUV light can be amplified during the interaction with atoms. We further prove that the above pictures are general for different doubly excited states by suitably varying the frequency of the IR field to coherently couple the corresponding states.
NASA Astrophysics Data System (ADS)
Liang, Wenkel; Isborn, Christine M.; Li, Xiaosong
2009-11-01
The calculation of doubly excited states is one of the major problems plaguing the modern day excited state workhorse methodology of linear response time dependent Hartree-Fock (TDHF) and density function theory (TDDFT). We have previously shown that the use of a resonantly tuned field within real-time TDHF and TDDFT is able to simultaneously excite both the α and β electrons to achieve the two-electron excited states of minimal basis H2 and HeH+ [C. M. Isborn and X. Li, J. Chem. Phys. 129, 204107 (2008)]. We now extend this method to many electron systems with the use of our Car-Parrinello density matrix search (CP-DMS) with a first-principles fictitious mass method for wave function optimization [X. Li, C. L. Moss, W. Liang, and Y. Feng, J. Chem. Phys. 130, 234115 (2009)]. Real-time TDHF/TDDFT is used during the application of the laser field perturbation, driving the electron density toward the doubly excited state. The CP-DMS method then converges the density to the nearest stationary state. We present these stationary state doubly excited state energies and properties at the HF and DFT levels for H2, HeH+, lithium hydride, ethylene, and butadiene.
Gibson, John K.; Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio; Haire, Richard G.
2008-12-08
The gas-phase reactivity of doubly-charged lanthanide cations, Ln2+ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), with alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) was studied by Fourier transform ion cyclotron resonance mass spectrometry. The reaction products consisted of different combinations of doubly-charged organometallic ions?adducts or species formed via metal-ion-induced hydrogen, dihydrogen, alkyl, or alkane eliminations from the hydrocarbons?and singly-charged ions that resulted from electron, hydride, or methide transfers from the hydrocarbons to the metal ions. The only lanthanide cations capable of activating the hydrocarbons to form doubly-charged organometallic ions were La2+, Ce2+, Gd2+, and Tb2+, which have ground-state or low-lying d1 electronic configurations. Lu2+, with an accessible d1 electronic configuration but a rather high electron affinity, reacted only through transfer channels. The remaining Ln2+ reacted via transfer channels or adduct formation. The different accessibilities of d1 electronic configurations and the range of electron affinities of the Ln2+ cations allowed for a detailed analysis of the trends for metal(2+) reactivity and the conditions for occurrence of bond activation, adduct formation, and electron, hydride, and methide transfers.
Koehler, Karsten; Braun, Hans; De Marees, Markus; Fusch, Gerhard; Fusch, Christoph; Mester, Joachim; Schaenzer, Wilhelm
2010-11-01
The assessment of nutrition and activity in athletes requires accurate and precise methods. The aim of this study was to validate a protocol for parallel assessment of diet and exercise against doubly labelled water, 24-h urea excretion, and respiratory gas exchange. The participants were 14 male triathletes under normal training conditions. Energy intake and doubly labelled water were weakly associated with each other (r = 0.69, standard error of estimate [SEE] = 304 kcal x day(-1)). Protein intake was strongly correlated with 24-h urea (r = 0.89) but showed considerable individual variation (SEE = 0.34 g kg(-1) x day(-1)). Total energy expenditure based on recorded activities was highly correlated with doubly labelled water (r = 0.95, SEE = 195 kcal x day(-1)) but was proportionally biased. During running and cycling, estimated exercise energy expenditure was highly correlated with gas exchange (running: r = 0.89, SEE = 1.6 kcal x min(-1); cycling: r = 0.95, SEE = 1.4 kcal x min(-1)). High exercise energy expenditure was slightly underestimated during running. For nutrition data, variations appear too large for precise measurements in individual athletes, which is a common problem of dietary assessment methods. Despite the high correlations of total energy expenditure and exercise energy expenditure with reference methods, a correction for systematic errors is necessary for the valid estimation of energetic requirements in individual athletes. PMID:20967672
NASA Technical Reports Server (NTRS)
Hunt, L. R.; Whitney, Paul
1987-01-01
A technique for identifying nonlinear systems was introduced, beginning with a single input-single output system. Assuming the system is initially at rest, the first kernel (first convolution integral in the continuous case or first convolution sum in the discrete case) was calculated. A controllable and observable linear realization was then obtained in a particular canonical form. The actual nonlinear system was probed with an appropriate input (or inputs) and the output (or outputs) determined. For the linear system, the input was computed that produces the same output. In the difference between the inputs to the nonlinear and linear systems, basic information was found about the nonlinear system. There is an interesting class of nonlinear systems for which this type of identification scheme should prove to be accurate.
NASA Astrophysics Data System (ADS)
Biktashev, V. N.; Tsyganov, M. A.
2016-08-01
Solitons, defined as nonlinear waves which can reflect from boundaries or transmit through each other, are found in conservative, fully integrable systems. Similar phenomena, dubbed quasi-solitons, have been observed also in dissipative, “excitable” systems, either at finely tuned parameters (near a bifurcation) or in systems with cross-diffusion. Here we demonstrate that quasi-solitons can be robustly observed in excitable systems with excitable kinetics and with self-diffusion only. This includes quasi-solitons of fixed shape (like KdV solitons) or envelope quasi-solitons (like NLS solitons). This can happen in systems with more than two components, and can be explained by effective cross-diffusion, which emerges via adiabatic elimination of a fast but diffusing component. We describe here a reduction procedure can be used for the search of complicated wave regimes in multi-component, stiff systems by studying simplified, soft systems.
Biktashev, V N; Tsyganov, M A
2016-01-01
Solitons, defined as nonlinear waves which can reflect from boundaries or transmit through each other, are found in conservative, fully integrable systems. Similar phenomena, dubbed quasi-solitons, have been observed also in dissipative, "excitable" systems, either at finely tuned parameters (near a bifurcation) or in systems with cross-diffusion. Here we demonstrate that quasi-solitons can be robustly observed in excitable systems with excitable kinetics and with self-diffusion only. This includes quasi-solitons of fixed shape (like KdV solitons) or envelope quasi-solitons (like NLS solitons). This can happen in systems with more than two components, and can be explained by effective cross-diffusion, which emerges via adiabatic elimination of a fast but diffusing component. We describe here a reduction procedure can be used for the search of complicated wave regimes in multi-component, stiff systems by studying simplified, soft systems. PMID:27491430
Biktashev, V. N.; Tsyganov, M. A.
2016-01-01
Solitons, defined as nonlinear waves which can reflect from boundaries or transmit through each other, are found in conservative, fully integrable systems. Similar phenomena, dubbed quasi-solitons, have been observed also in dissipative, “excitable” systems, either at finely tuned parameters (near a bifurcation) or in systems with cross-diffusion. Here we demonstrate that quasi-solitons can be robustly observed in excitable systems with excitable kinetics and with self-diffusion only. This includes quasi-solitons of fixed shape (like KdV solitons) or envelope quasi-solitons (like NLS solitons). This can happen in systems with more than two components, and can be explained by effective cross-diffusion, which emerges via adiabatic elimination of a fast but diffusing component. We describe here a reduction procedure can be used for the search of complicated wave regimes in multi-component, stiff systems by studying simplified, soft systems. PMID:27491430
H2O diffusion in Mount Changbai peralkaline rhyolitic melt
NASA Astrophysics Data System (ADS)
Zhang, Y.; Xu, Z.; Wang, H.; Behrens, H.
2008-05-01
For quantitative modeling of bubble growth and volcanic eruption dynamics, it is necessary to know H2O diffusivity in the melt. Mount Changbai Volcano at the border of China and North Korea has produced explosive peralkaline rhyolitic eruptions, including a 30-km3 eruption with an age of 1 ky (Horn and Schmincke, 2000). H2O diffusivity is expected to be greater in a peralkaline rhyolitic melt than a calc-alkaline rhyolitic melt. We have experimentally investigated H2O diffusion in Mount Changbai peralkaline rhyolite. Because phenocryst-free glass is not available from Mount Changbai eruption products, the starting materials (nominally dry and hydrous) are synthesized. The diffusion couple technique, with one half dry and the other half wet, is adopted. Three high- temperature experiments have been carried out at 500 MPa and one at 1500 MPa in a piston-cylinder apparatus. After the experiment, the sample is prepared into a doubly-polished section of about 0.2 mm thickness, which is analyzed by a Perkin-Elmer FTIR microscope. The data are fit following the procedures of Zhang and Behrens (2000) and Ni and Zhang (2008). Preliminary data show that H2O diffusivity in peralkaline rhyolitic melt is greater than that in calc-alkaline rhyolitic melt (Zhang and Behrens, 2000), as expected. The exact difference depends on temperature and pressure, and the ratio of diffusivity in the peralkaline rhyolitic melt to that in the calc-alkaline rhyolitic melt ranges from 1 to 3. More experiments will be conducted on this melt to provide the basic data for specific modeling of bubble growth and volcanic eruption dynamics in past and future Mount Changbai eruptions and other peralkaline rhyolitic eruptions. References: Horn S and Schmincke H U (2000) Bull. Volcanol., 61, 537. Ni H and Zhang Y (2008) Chem. Geol., doi: 10.1016/j.chemgeo.2008.01.011. Zhang Y and Behrens H (2000) Chem. Geol., 169, 243.
Restoration of rhythmicity in diffusively coupled dynamical networks
Zou, Wei; Senthilkumar, D. V.; Nagao, Raphael; Kiss, István Z.; Tang, Yang; Koseska, Aneta; Duan, Jinqiao; Kurths, Jürgen
2015-01-01
Oscillatory behaviour is essential for proper functioning of various physical and biological processes. However, diffusive coupling is capable of suppressing intrinsic oscillations due to the manifestation of the phenomena of amplitude and oscillation deaths. Here we present a scheme to revoke these quenching states in diffusively coupled dynamical networks, and demonstrate the approach in experiments with an oscillatory chemical reaction. By introducing a simple feedback factor in the diffusive coupling, we show that the stable (in)homogeneous steady states can be effectively destabilized to restore dynamic behaviours of coupled systems. Even a feeble deviation from the normal diffusive coupling drastically shrinks the death regions in the parameter space. The generality of our method is corroborated in diverse non-linear systems of diffusively coupled paradigmatic models with various death scenarios. Our study provides a general framework to strengthen the robustness of dynamic activity in diffusively coupled dynamical networks. PMID:26173555
Configurational diffusion of asphaltenes in fresh and aged catalysts extrudates
Guin, J.A.; Tarrer, A.R.
1992-01-01
Objective is to determine the relation between the size and shape of coal and petroleum micromolecules and their diffusion rates in catalyst pore structures. Diffusivity measurements will be performed with aged catalysts from coal liquefaction pilot plants. During this period, equilibrium adsorption experiments were carried out to determine the adsorption isotherm needed in the data analysis. The equilibrium isotherm for quinoline in cyclohexane with fresh Shell 324 (Ni-Mo/Al[sub 2]O[sub 3]) catalyst was found to be nonlinear and well represented by the Freundlich adsorption isotherm. The effective diffusivity was found to be less than the estimated pore diffusivity for nonrestrictive diffusion, indicating pore restriction for quinoline diffusion in cyclohexane with Shell 324 catalyst.
Restoration of rhythmicity in diffusively coupled dynamical networks.
Zou, Wei; Senthilkumar, D V; Nagao, Raphael; Kiss, István Z; Tang, Yang; Koseska, Aneta; Duan, Jinqiao; Kurths, Jürgen
2015-01-01
Oscillatory behaviour is essential for proper functioning of various physical and biological processes. However, diffusive coupling is capable of suppressing intrinsic oscillations due to the manifestation of the phenomena of amplitude and oscillation deaths. Here we present a scheme to revoke these quenching states in diffusively coupled dynamical networks, and demonstrate the approach in experiments with an oscillatory chemical reaction. By introducing a simple feedback factor in the diffusive coupling, we show that the stable (in)homogeneous steady states can be effectively destabilized to restore dynamic behaviours of coupled systems. Even a feeble deviation from the normal diffusive coupling drastically shrinks the death regions in the parameter space. The generality of our method is corroborated in diverse non-linear systems of diffusively coupled paradigmatic models with various death scenarios. Our study provides a general framework to strengthen the robustness of dynamic activity in diffusively coupled dynamical networks. PMID:26173555
Restoration of rhythmicity in diffusively coupled dynamical networks
NASA Astrophysics Data System (ADS)
Zou, Wei; Senthilkumar, D. V.; Nagao, Raphael; Kiss, István Z.; Tang, Yang; Koseska, Aneta; Duan, Jinqiao; Kurths, Jürgen
2015-07-01
Oscillatory behaviour is essential for proper functioning of various physical and biological processes. However, diffusive coupling is capable of suppressing intrinsic oscillations due to the manifestation of the phenomena of amplitude and oscillation deaths. Here we present a scheme to revoke these quenching states in diffusively coupled dynamical networks, and demonstrate the approach in experiments with an oscillatory chemical reaction. By introducing a simple feedback factor in the diffusive coupling, we show that the stable (in)homogeneous steady states can be effectively destabilized to restore dynamic behaviours of coupled systems. Even a feeble deviation from the normal diffusive coupling drastically shrinks the death regions in the parameter space. The generality of our method is corroborated in diverse non-linear systems of diffusively coupled paradigmatic models with various death scenarios. Our study provides a general framework to strengthen the robustness of dynamic activity in diffusively coupled dynamical networks.
A hybrid neurocomputing/numerical strategy for nonlinear structural analysis
NASA Technical Reports Server (NTRS)
Szewczyk, Z. Peter; Noor, Ahmed K.
1995-01-01
A hybrid neurocomputing/numerical strategy is presented for geometrically nonlinear analysis of structures. The strategy combines model-free data processing capabilities of computational neural networks with a Pade approximants-based perturbation technique to predict partial information about the nonlinear response of structures. In the hybrid strategy, multilayer feedforward neural networks are used to extend the validity of solutions by using training samples produced by Pade approximations to the Taylor series expansion of the response function. The range of validity of the training samples is taken to be the radius of convergence of Pade approximants and is estimated by setting a tolerance on the diverging approximants. The norm of residual vector of unbalanced forces in a given element is used as a measure to assess the quality of network predictions. To further increase the accuracy and the range of network predictions, additional training data are generated by either applying linear regression to weight matrices or expanding the training data by using predicted coefficients in a Taylor series. The effectiveness of the hybrid strategy is assessed by performing large-deflection analysis of a doubly-curved composite panel with a circular cutout, and postbuckling analyses of stiffened composite panels subjected to an in-plane edge shear load. In all the problems considered, the hybrid strategy is used to predict selective information about the structural response, namely the total strain energy and the maximum displacement components only.
DEVELOPMENT OF SPLIT-OPERATOR, PETROV-GALERKIN METHODS TO SIMULATE TRANSPORT AND DIFFUSION PROBLEMS
The rate at which contaminants in groundwater undergo sorption and desorption is routinely described using diffusion models. Such approaches, when incorporated into transport models, lead to large systems of coupled equations, often nonlinear. This has restricted applications of ...
Microfabricated diffusion source
Oborny, Michael C.; Frye-Mason, Gregory C.; Manginell, Ronald P.
2008-07-15
A microfabricated diffusion source to provide for a controlled diffusion rate of a vapor comprises a porous reservoir formed in a substrate that can be filled with a liquid, a headspace cavity for evaporation of the vapor therein, a diffusion channel to provide a controlled diffusion of the vapor, and an outlet to release the vapor into a gas stream. The microfabricated diffusion source can provide a calibration standard for a microanalytical system. The microanalytical system with an integral diffusion source can be fabricated with microelectromechanical systems technologies.
Computer simulation of the velocity diffusion of cosmic rays
NASA Technical Reports Server (NTRS)
Kaiser, T. B.; Birmingham, T. J.; Jones, F. C.
1977-01-01
Monte Carlo simulation experiments were performed in order to study the velocity diffusion of charged particles in a static turbulent magnetic field. By following orbits of particles moving in a large ensemble of random magnetic field realizations with suitable chosen statistical properties, a pitch-angle diffusion coefficient is derived. Results are presented for a variety of particle rigidities and rms random field strengths and compared with the predictions of standard quasi-linear theory and the nonlinear partially averaged field theory.
Galactic civilizations: Population dynamics and interstellar diffusion
NASA Technical Reports Server (NTRS)
Newman, W. I.; Sagan, C.
1978-01-01
The interstellar diffusion of galactic civilizations is reexamined by potential theory; both numerical and analytical solutions are derived for the nonlinear partial differential equations which specify a range of relevant models, drawn from blast wave physics, soil science, and, especially, population biology. An essential feature of these models is that, for all civilizations, population growth must be limited by the carrying capacity of the environment. Dispersal is fundamentally a diffusion process; a density-dependent diffusivity describes interstellar emigration. Two models are considered: the first describing zero population growth (ZPG), and the second which also includes local growth and saturation of a planetary population, and for which an asymptotic traveling wave solution is found.
Vector Diffusion Maps and the Connection Laplacian
Singer, A.; Wu, H.-T.
2013-01-01
We introduce vector diffusion maps (VDM), a new mathematical framework for organizing and analyzing massive high-dimensional data sets, images, and shapes. VDM is a mathematical and algorithmic generalization of diffusion maps and other nonlinear dimensionality reduction methods, such as LLE, ISOMAP, and Laplacian eigenmaps. While existing methods are either directly or indirectly related to the heat kernel for functions over the data, VDM is based on the heat kernel for vector fields. VDM provides tools for organizing complex data sets, embedding them in a low-dimensional space, and interpolating and regressing vector fields over the data. In particular, it equips the data with a metric, which we refer to as the vector diffusion distance. In the manifold learning setup, where the data set is distributed on a low-dimensional manifold ℳd embedded in ℝp, we prove the relation between VDM and the connection Laplacian operator for vector fields over the manifold. PMID:24415793
Piper, Matthew D.W.; Selman, Colin; Speakman, John R.; Partridge, Linda
2014-01-01
Energy expenditure is a key variable in the study of ageing, and the fruit fly Drosophila melanogaster is a model organism that has been used to make step changes in our understanding of the ageing process. Standard methods for measurement of energy expenditure involve placing individuals in metabolic chambers where their oxygen consumption and CO2 production can be quantified. These measurements require separating individuals from any social context, and may only poorly reflect the environment in which the animals normally live. The doubly-labeled water (DLW) method is an isotope-based technique for measuring energy expenditure which overcomes these problems. However, technical challenges mean that the smallest animals this method has been previously applied to weighed 50–200 mg. We overcame these technical challenges to measure energy demands in Drosophila weighing 0.78 mg. Mass-specific energy expenditure varied between 43 and 65 mW·g−1. These estimates are considerably higher than estimates using indirect calorimetry of Drosophila in small metabolic chambers (around 18 mW·g−1). The methodology we have established extends downwards by three orders of magnitude the size of animals that can be measured using DLW. This approach may be of considerable value in future ageing research attempting to understand the genetic and genomic basis of ageing. PMID:25269676
Near-degenerate stereomorphs of the doubly-chiral hcp-{213̅1} surface
NASA Astrophysics Data System (ADS)
Jenkins, S. J.
2010-09-01
The surfaces of hcp crystals can show a variety of structural features and classes of symmetry that differ markedly from those of simpler fcc or bcc crystals. The hcp-{213̅1} surface, for example, can occur in four distinct stereomorphs, interconverted by a combination of mirror operations (linking degenerate enantiomorphically related surfaces) and/or the removal of the outermost atomic layer (linking non-degenerate diamorphically related surfaces). The strict pattern of degeneracy amongst these stereomorphs is analogous to that found for molecules with two chiral centres, and hence it is possible to view this system as doubly-chiral. Simple nearest-neighbour bond-counting arguments, however, suggest that for {213̅1} even the diamorphically related cases should be near-degenerate, despite the fact that they differ in having either a notably short or notably long interlayer spacing between the outermost layers (ideal spacing ratio 1:5). In the present work, this counterintuitive result is confirmed at the level of density functional theory, both for the ideal and relaxed {213̅1} surfaces of Co, Ru and Re.
Total energy expenditure in burned children using the doubly labeled water technique
Goran, M.I.; Peters, E.J.; Herndon, D.N.; Wolfe, R.R. )
1990-10-01
Total energy expenditure (TEE) was measured in 15 burned children with the doubly labeled water technique. Application of the technique in burned children required evaluation of potential errors resulting from nutritional intake altering background enrichments during studies and from the high rate of water turnover relative to CO2 production. Five studies were discarded because of these potential problems. TEE was 1.33 +/- 0.27 times predicted basal energy expenditure (BEE), and in studies where resting energy expenditure (REE) was simultaneously measured, TEE was 1.18 +/- 0.17 times REE, which in turn was 1.16 +/- 0.10 times predicted BEE. TEE was significantly correlated with measured REE (r2 = 0.92) but not with predicted BEE. These studies substantiate the advantage of measuring REE to predict TEE in severely burned patients as opposed to relying on standardized equations. Therefore we recommend that optimal nutritional support will be achieved in convalescent burned children by multiplying REE by an activity factor of 1.2.
Piper, Matthew D W; Selman, Colin; Speakman, John R; Partridge, Linda
2014-09-20
Energy expenditure is a key variable in the study of ageing, and the fruit fly Drosophila melanogaster is a model organism that has been used to make step changes in our understanding of the ageing process. Standard methods for measurement of energy expenditure involve placing individuals in metabolic chambers where their oxygen consumption and CO2 production can be quantified. These measurements require separating individuals from any social context, and may only poorly reflect the environment in which the animals normally live. The doubly-labeled water (DLW) method is an isotope-based technique for measuring energy expenditure which overcomes these problems. However, technical challenges mean that the smallest animals this method has been previously applied to weighed 50-200 mg. We overcame these technical challenges to measure energy demands in Drosophila weighing 0.78 mg. Mass-specific energy expenditure varied between 43 and 65 mW·g(-1). These estimates are considerably higher than estimates using indirect calorimetry of Drosophila in small metabolic chambers (around 18 mW·g(-1)). The methodology we have established extends downwards by three orders of magnitude the size of animals that can be measured using DLW. This approach may be of considerable value in future ageing research attempting to understand the genetic and genomic basis of ageing.
Doubly charged Higgs bosons and three-lepton signatures in the Higgs triplet model
Akeroyd, A. G.; Chiang, C.-W.
2009-12-01
Doubly charged Higgs bosons, H{sup {+-}}{sup {+-}}, are being searched for in the Tevatron experiments. The most recent search by the D0 Collaboration seeks three muons ({mu}{sup {+-}}{mu}{sup {+-}}{mu}{sup {+-}}), which are assumed to originate from the pair-production process, qq{yields}H{sup ++}H{sup --}, followed by the decay H{sup {+-}}{sup {+-}}{yields}{mu}{sup {+-}}{mu}{sup {+-}}. In this three-lepton (3l) channel there are six distinct signatures for l=e or {mu}. In the context of the Higgs Triplet Model, we quantify the dependence of the event numbers for the 3l channels on the parameters of the neutrino mass matrix. It is also shown that the inclusion of the production mechanism qq{sup '}{yields}H{sup {+-}}{sup {+-}}H{sup {+-}}, followed by the decay H{sup {+-}}{yields}l{sup {+-}}{nu}, would significantly increase the discovery potential in these channels. We then provide perspectives on the production of these channels at the Tevatron and LHC.
Exploration of Doubly Thermal Phase Transition Process of PDEGA-b-PDMA-b-PVCL in Water.
Ye, Zhangxin; Li, Youcheng; An, Zesheng; Wu, Peiyi
2016-07-01
Understanding of phase transition mechanism of thermoresponsive polymers is the basis for the rational design of smart materials with predictable properties. Linear ABC triblock terpolymer poly(di(ethylene glycol)ethyl ether acrylate)-b-poly(N,N-dimethylacrylamide)-b-poly(N-vinylcaprolactam) (PDEGA-b-PDMA-b-PVCL) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The doubly thermal phase transition of PDEGA-b-PDMA-b-PVCL in aqueous solution was investigated by a combination of nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), turbidimetry, and dynamic light scattering (DLS). The terpolymer self-assembles into micelles with PDEGA being the core-forming block during the first lower critical solution temperature (LCST) transition corresponding to PDEGA, which is followed by a second LCST transition corresponding to PVCL, resulting in the formation of micellar aggregates. The PDMA middle segment plays an important role as an isolation zone to prevent cooperative dehydration of the PDEGA and PVCL segments, and therefore, two independent LCST transitions corresponding to PDEGA and PVCL were observed. Furthermore, FT-IR with perturbation correlation moving window (PCMW) and two-dimensional spectroscopy (2DCOS) was applied to elucidate the two-step phase transition mechanism of this terpolymer. It was observed that the CH, ester carbonyl, and ether groups of PDEGA change prior to the CH and amide carbonyl groups of PVCL, further supporting that the two phase transitions corresponding to PDEGA and PVCL indeed occur without mutual interferences. PMID:27299984
Van Raemdonck, Mario; Alcoba, Diego R; Poelmans, Ward; De Baerdemacker, Stijn; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Van Neck, Dimitri; Bultinck, Patrick
2015-09-14
A class of polynomial scaling methods that approximate Doubly Occupied Configuration Interaction (DOCI) wave functions and improve the description of dynamic correlation is introduced. The accuracy of the resulting wave functions is analysed by comparing energies and studying the overlap between the newly developed methods and full configuration interaction wave functions, showing that a low energy does not necessarily entail a good approximation of the exact wave function. Due to the dependence of DOCI wave functions on the single-particle basis chosen, several orbital optimisation algorithms are introduced. An energy-based algorithm using the simulated annealing method is used as a benchmark. As a computationally more affordable alternative, a seniority number minimising algorithm is developed and compared to the energy based one revealing that the seniority minimising orbital set performs well. Given a well-chosen orbital basis, it is shown that the newly developed DOCI based wave functions are especially suitable for the computationally efficient description of static correlation and to lesser extent dynamic correlation.
Energy expenditure and fluid production in hyperbaric He-O2 environments using doubly labeled water.
Seale, J L; Thorp, J W; Conway, J M; Rumpler, W V; Haberman, K J
1994-06-01
Energy expenditure (EE), carbon dioxide production (rCO2), water turnover (rH2O), and urine production (UP) were measured to determine nutrient requirements of U.S. Navy divers during saturation dives. Parameters were measured in a normal surface environment (n = 10) and in 0.56 MPa (n = 9) and 3.17 MPa (n = 11) helium-oxygen environments. Daily EE, rCO2, and rH2O were measured with the doubly labeled water method for 10-14 days in each environment. Daily UP was determined by 24-h urine collection for 5- to 10-day periods in each environment. Divers consumed a mixed diet composed of 30% calories from fat, 15% protein, and 55% carbohydrate. Both EE and rCO2 increased significantly relative to surface conditions at 0.56 MPa (13 +/- 4% and 11 +/- 4%) and 3.17 MPa (14 +/- 4% and 11 +/- 3%), but there was no difference between dives. Water turnover was not significantly affected by the hyperbaric environment. UP was significantly greater than surface conditions at 0.56 MPa (53 +/- 19%) but not at 3.17 MPa (38 +/- 18%). Increased EE is attributed to thermal stress caused by the helium-oxygen environment. Increased UP may have been caused by decreased evaporative water loss. PMID:7914783
NASA Astrophysics Data System (ADS)
Liu, Yuxiang; Barnett, Alex H.
2016-11-01
We present a high-order accurate boundary-based solver for three-dimensional (3D) frequency-domain scattering from a doubly-periodic grating of smooth axisymmetric sound-hard or transmission obstacles. We build the one-obstacle solution operator using separation into P azimuthal modes via the FFT, the method of fundamental solutions (with N proxy points lying on a curve), and dense direct least-squares solves; the effort is O (N3 P) with a small constant. Periodizing then combines fast multipole summation of nearest neighbors with an auxiliary global Helmholtz basis expansion to represent the distant contributions, and enforcing quasiperiodicity and radiation conditions on the unit cell walls. Eliminating the auxiliary coefficients, and preconditioning with the one-obstacle solution operator, leaves a well-conditioned square linear system that is solved iteratively. The solution time per incident wave is then O (NP) at fixed frequency. Our scheme avoids singular quadratures, periodic Green's functions, and lattice sums, and its convergence rate is unaffected by resonances within obstacles. We include numerical examples such as scattering from a grating of period 13 λ × 13 λ comprising highly-resonant sound-hard "cups" each needing NP = 64800 surface unknowns, to 10-digit accuracy, in half an hour on a desktop.
Production and properties of singly, doubly, and triply charged N/sub 2/ clusters
Scheier, P.; Stamatovic, A.; Maerk, T.D.
1988-04-01
Clusters of N/sub 2/ molecules formed in a supersonic nozzle expansion have been studied by electron impact ionization mass spectrometry. Mass resolved spectra (with n up to 190) show three homologous series, i.e., consisting of (N/sub 2/)/sup +//sub n/, (N/sub 2/)/sub n/N+, and ((N/sub 2/)/sub n/ N)/sup 2 +/ ions. The distribution of (N/sub 2/)/sup +//sub n/ ions shows distinct magic number effects. Moreover, there is evidence for the existence of (N/sub 2/)/sup 2 +//sub n/ and (N/sub 2/)/sup 3 +//sub n/ ions. The critical appearance sizes of observed multiply charged cluster ions are (N/sub 2/)/sup 2 +//sub 99/, (N/sub 2/)/sub 99/N/sup 2 +/, and (N/sub 2/)/sup 3 +//sub 215/. These results are compared with theoretical predictions. Moreover, a study of the electron energy dependence of singly and doubly charged N/sub 2/ cluster ions close to threshold (appearance energies) gives new insight into the ionization mechanism
New Exotic Meson and Baryon Resonances from Doubly Heavy Hadronic Molecules.
Karliner, Marek; Rosner, Jonathan L
2015-09-18
We predict several new exotic doubly heavy hadronic resonances, inferring from the observed exotic bottomoniumlike and charmoniumlike narrow states X(3872), Z_{b}(10610), Z_{b}(10650), Z_{c}(3900), and Z_{c}(4020/4025). We interpret the binding mechanism as mostly molecularlike isospin-exchange attraction between two heavy-light mesons in a relative S-wave state. We then generalize it to other systems containing two heavy hadrons which can couple through isospin exchange. The new predicted states include resonances in meson-meson, meson-baryon, baryon-baryon, and baryon-antibaryon channels. These include those giving rise to final states involving a heavy quark Q=c,b and antiquark Q[over ¯]^{'}=c[over ¯],b[over ¯], namely, DD[over ¯]^{*}, D^{*}D[over ¯]^{*}, D^{*}B^{*}, B[over ¯]B^{*}, B[over ¯]^{*}B^{*}, Σ_{c}D[over ¯]^{*}, Σ_{c}B^{*}, Σ_{b}D[over ¯]^{*}, Σ_{b}B^{*}, Σ_{c}Σ[over ¯]_{c}, Σ_{c}Λ[over ¯]_{c}, Σ_{c}Λ[over ¯]_{b}, Σ_{b}Σ[over ¯]_{b}, Σ_{b}Λ[over ¯]_{b}, and Σ_{b}Λ[over ¯]_{c}, as well as corresponding S-wave states giving rise to QQ^{'} or Q[over ¯]Q[over ¯]^{'}. PMID:26430989
On the stability of Einstein static universe in doubly general relativity scenario
NASA Astrophysics Data System (ADS)
Khodadi, M.; Heydarzade, Y.; Nozari, K.; Darabi, F.
2015-12-01
By presenting a relation between the average energy of the ensemble of probe photons and the energy density of the universe, in the context of gravity's rainbow or the doubly general relativity scenario, we introduce a rainbow FRW universe model. By analyzing the fixed points in the flat FRW model modified by two well-known rainbow functions, we find that the finite time singularity avoidance (i.e. Big Bang) may still remain as a problem. Then we follow the "emergent universe" scenario in which there is no beginning of time and consequently there is no Big-Bang singularity. Moreover, we study the impact of high energy quantum gravity modifications related to the gravity's rainbow on the stability conditions of an "Einstein static universe" (ESU). We find that independent of the particular rainbow function, the positive energy condition dictates a positive spatial curvature for the universe. In fact, without raising a nonphysical energy condition in the quantum gravity regimes, we can observe agreement between gravity's rainbow scenario and the basic assumption of the modern version of the "emergent universe". We show that in the absence and presence of an energy-dependent cosmological constant Λ (ɛ ), a stable Einstein static solution is available versus the homogeneous and linear scalar perturbations under the variety of the obtained conditions. Also, we explore the stability of ESU against the vector and tensor perturbations.
Marcus, Sue M; Stuart, Elizabeth A; Wang, Pei; Shadish, William R; Steiner, Peter M
2012-06-01
Although randomized studies have high internal validity, generalizability of the estimated causal effect from randomized clinical trials to real-world clinical or educational practice may be limited. We consider the implication of randomized assignment to treatment, as compared with choice of preferred treatment as it occurs in real-world conditions. Compliance, engagement, or motivation may be better with a preferred treatment, and this can complicate the generalizability of results from randomized trials. The doubly randomized preference trial (DRPT) is a hybrid randomized and nonrandomized design that allows for estimation of the causal effect of randomization versus treatment preference. In the DRPT, individuals are first randomized to either randomized assignment or choice assignment. Those in the randomized assignment group are then randomized to treatment or control, and those in the choice group receive their preference of treatment versus control. Using the potential outcomes framework, we apply the algebra of conditional independence to show how the DRPT can be used to derive an unbiased estimate of the causal effect of randomization versus preference for each of the treatment and comparison conditions. Also, we show how these results can be implemented using full matching on the propensity score. The methodology is illustrated with a DRPT of introductory psychology students who were randomized to randomized assignment or preference of mathematics versus vocabulary training. We found a small to moderate benefit of preference versus randomization with respect to the mathematics outcome for those who received mathematics training.
Singly and Doubly Charmed $J=1/2$ Baryon Spectrum from Lattice QCD
Liuming Liu; Lin, Huey-Wen; Orginos, Kostas; Walker-Loud, Andre
2010-05-01
We compute the masses of the singly and doubly charmed baryons in full QCD using the relativistic Fermilab action for the charm quark. For the light quarks we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We use the low-lying charmonium spectrum to tune our heavy-quark action and as a guide to understanding the discretization errors associated with the heavy quark. Our results are in good agreement with experiment within our systematicss, except for the spin-1/2 $\\Xi_{cc}$, for which we predict the isospin averaged mass to be $M_{\\Xi_{cc}} = 3665 \\pm17 \\pm14\\, {}^{+0}_{-35}$~{MeV} (here the first uncertainty is statistical, the second systematic and the third an estimate of lattice discretization errors). In addition, we predict the splitting of the (isospin averaged) spin-1/2 $\\O_{cc}$ with the $\\Xi_{cc}$ to be $M_{\\O_{cc}} - M_{\\Xi_{cc}} = 98 \\pm9 \\pm22$~{MeV} (in this mass splitting, the leading discretization errors cancel). This corresponds to a prediction of $M_{\\O_{cc}} = 3763\\pm9\\pm44\\, {}^{+0}_{-35}$~{MeV}.
Fully Coupled Channel Approach to Doubly Strange s-Shell Hypernuclei
Nemura, H.; Shinmura, S.; Akaishi, Y.; Myint, Khin Swe
2005-05-27
We describe ab initio calculations of doubly strange, S=-2, s-shell hypernuclei ({sub {lambda}}{sub {lambda}}{sup 4}H, {sub {lambda}}{sub {lambda}}{sup 5}H, {sub {lambda}}{sub {lambda}}{sup 5}He, and {sub {lambda}}{sub {lambda}}{sup 6}He) as a first attempt to explore the few-body problem of the full-coupled channel scheme for these systems. The wave function includes {lambda}{lambda}, {lambda}{sigma}, N{xi}, and {sigma}{sigma} channels. Minnesota NN, D2{sup '} YN, and simulated YY potentials based on the Nijmegen hard-core model are used. Bound-state solutions of these systems are obtained. We find that a set of phenomenological B{sub 8}B{sub 8} interactions among the octet baryons in S=0,-1, and -2 sectors, which is consistent with all of the available experimental binding energies of S=0,-1, and -2 s-shell (hyper)nuclei, can predict a particle stable bound state of {sub {lambda}}{sub {lambda}}{sup 4}H. For {sub {lambda}}{sub {lambda}}{sup 5}H and {sub {lambda}}{sub {lambda}}{sup 5}He, {lambda}N-{sigma}N and {xi}N-{lambda}{sigma} potentials significantly affect the net {lambda}{lambda}-N{xi} coupling, and a large {xi} probability is obtained even for a weaker {lambda}{lambda}-N{xi} potential.
Excited state mass spectra of doubly heavy baryons {Ω _{cc}}, {Ω _{bb}}, and {Ω _{bc}}
NASA Astrophysics Data System (ADS)
Shah, Zalak; Thakkar, Kaushal; Rai, Ajay Kumar
2016-10-01
We discuss the mass spectrum of Ω baryon with two heavy quarks and one light quark ( ccs, bbs, and bcs). The main goal of the paper is to calculate the ground state masses and after that, the positive and negative parity excited states masses are also obtained within a hypercentral constituent quark model, using Coulomb plus linear potential framework. We also added a first order correction to the potential. The mass spectra up to 5S for radial excited states and 1P-5P, 1D-4D, and 1F-2F states for orbital excited states are computed for Ω _{cc}, Ω _{bb}, and Ω _{bc} baryons. Our obtained results are compared with other theoretical predictions, which could be a useful complementary tool for the interpretation of experimentally unknown heavy baryon spectra. The Regge trajectory is constructed in both the (n_r, M2) and the ( J, M2) planes for Ω _{cc}, Ω _{bb}, and Ω _{bc} baryons and their slopes and intercepts are also determined. Magnetic moments of doubly heavy Ω 's are also calculated.
Vargas, Jaime; Pérez, Montse; Toro, Jorge; Astorga, Marcela P.
2015-01-01
This study presents evidence, using sequences of ribosomal 16S and COI mtDNA, for the presence of two mitochondrial genomes in Perumytilus purpuratus. This may be considered evidence of doubly uniparental mtDNA inheritance. The presence of the two types of mitochondrial genomes differentiates females from males. The F genome was found in the somatic and gonadal tissues of females and in the somatic tissues of males; the M genome was found in the gonads and mantle of males only. For the mitochondrial 16S region, ten haplotypes were found for the F genome (nucleotide diversity 0.004), and 7 haplotypes for the M genome (nucleotide diversity 0.001), with a distance Dxy of 0.125 and divergence Kxy of 60.33%. For the COI gene 17 haplotypes were found for the F genome (nucleotide diversity 0.009), and 10 haplotypes for the M genome (nucleotide diversity 0.010), with a genetic distance Dxy of 0.184 and divergence Kxy of 99.97%. Our results report the presence of two well-differentiated, sex-specific types of mitochondrial genome (one present in the male gonad, the other in the female gonad), implying the presence of DUI in P. purpuratus. These results indicate that care must be taken in phylogenetic comparisons using mtDNA sequences of P. purpuratus without considering the sex of the individuals. PMID:26273220
Light doubly charged Higgs boson via the WW^* channel at LHC
NASA Astrophysics Data System (ADS)
Kang, Zhaofeng; Li, Jinmian; Li, Tianjun; Liu, Yandong; Ning, Guo-Zhu
2015-12-01
The doubly charged Higgs bosons H^{± ± } searches at the large hadron collider (LHC) have been studied extensively and strong bound is available for H^{± ± } dominantly decaying into a pair of same-sign di-leptons. In this paper we point out that there is a large cavity in the light H^{± ± } mass region left unexcluded. In particular, H^{± ± } can dominantly decay into WW or WW^* (For instance, in the type-II seesaw mechanism the triplet acquires a vacuum expectation value around 1 GeV), and then it is found that H^{± ± } with mass even below 2m_W remains untouched by the current collider searches. Searching for such a H^{± ± } at the LHC is the topic of this paper. We perform detailed signal and background simulation, especially including the non-prompt tbar{t} background which is the dominant one nevertheless ignored before. We show that such H^{± ± } should be observable at the 14 TeV LHC with 10-30 fb^{-1} integrated luminosity.
Ab initio Approach to Effective Single-Particle Energies in Doubly Closed Shell Nuclei
Duguet, T.
2012-01-01
The present work discusses, from an ab initio standpoint, the definition, the meaning, and the usefulness of effective single-particle energies (ESPEs) in doubly closed shell nuclei. We perform coupled-cluster calculations to quantify to what extent selected closed-shell nuclei in the oxygen and calcium isotopic chains can effectively be mapped onto an effective independent-particle picture. To do so, we revisit in detail the notion of ESPEs in the context of strongly correlated many-nucleon systems and illustrate the necessity of extracting ESPEs through the diagonalization of the centroid matrix, as originally argued by Baranger. For the purpose of illustration, we analyze the impact of correlations on observable one-nucleon separation energies and nonobservable ESPEs in selected closed-shell oxygen and calcium isotopes. We then state and illustrate the nonobservability of ESPEs. Similarly to spectroscopic factors, ESPEs can indeed be modified by a redefinition of inaccessible quantities while leaving actual observables unchanged. This leads to the absolute necessity of employing consistent structure and reaction models based on the same nuclear Hamiltonian to extract the shell structure in a meaningful fashion from experimental data.
Applicability of the doubly labelled water method to the rhinoceros auklet, Cerorhinca monocerata
Shirai, Masaki; Ito, Motohiro; Yoda, Ken; Niizuma, Yasuaki
2012-01-01
Summary The doubly labelled water (DLW) method is an isotope-based technique that is used to measure the metabolic rates of free-living animals. We validated the DLW method for measuring metabolic rates in five rhinoceros auklets (Cerorhinca monocerata) compared with simultaneous measurements using the respirometric method. We calculated the CO2 production rate of four auklets (mean initial body mass: 552 g±36 s.d.) injected with DLW, using the one- and two-pool models. The metabolic rate during the 24-h measurements in a respirometric chamber for resting auklets averaged 16.30±1.66 kJ h−1 (n = 4). The metabolic rates determined using the one- and two-pool models in the DLW method for the same period as the respirometric measurement averaged 16.61±2.13 kJ h−1 (n = 4) and 16.16±2.10 kJ h−1 (n = 4), respectively. The mean absolute percent error between the DLW and respirometric methods was 8.04% using the one-pool model and was slightly better than that with the two-pool model. The differences in value between the DLW and respirometric methods are probably due to oxygen isotope turnover, which eliminated only 10–14% of the initial enrichment excess. PMID:23213394
Adaptation of the doubly labeled water method for subjects consuming isotopically enriched water.
Gretebeck, R J; Schoeller, D A; Socki, R A; Davis-Street, J; Gibson, E K; Schulz, L O; Lane, H W
1997-02-01
The use of doubly labeled water (DLW) to measure energy expenditure is subject to error if the background abundance of the oxygen and hydrogen isotope tracers changes during the test period. This study evaluated the accuracy and precision of different methods by which such background isotope changes can be corrected, including a modified method that allows prediction of the baseline that would be achieved if subjects were to consume water from a given source indefinitely. Subjects in this study were eight women (4 test subjects and 4 control subjects) who consumed for 28 days water enriched to resemble drinking water aboard the United States space shuttle. Test subjects and control subjects were given a DLW dose on days 1 and 15, respectively. The change to an enriched water source produced a bias in expenditure calculations that exceeded 2.9 MJ/day (35%), relative to calculations from intake-balance. The proposed correction based on the predicted final abundance of 18O and deuterium after equilibration to the new water source eliminated this bias, as did the traditional use of a control group. This new modified correction method is advantageous under field conditions when subject numbers are limited.
20 {mu}s isomeric state in doubly odd {sub 61}{sup 134}Pm
Cullen, D. M.; Mason, P. J. R; Rigby, S. V.; Kishada, A. M.; Varley, B. J.; Scholey, C.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Leppaenen, A.-P.; Maentyniemi, K.; Nieminen, P.; Nyman, M.; Pakarinen, J.
2009-08-15
Recoil-isomer tagging at the Accelerator Laboratory of the University of Jyvaeskylae has been used to establish the isomeric nature of a known (7{sup -}) excited state in the doubly odd nucleus {sup 134}Pm. The isomeric state was determined to have a half-life of 20(1) {mu}s and was populated from the decay of a {pi}h{sub 11/2} x {nu}h{sub 11/2} band using the {sup 92}Mo({sup 54}Fe,2{alpha}3pn) reaction at 305 and 315 MeV. The isomer decays by a 71-keV transition that provides an intermediate step in linking the established {sup 134}Pm high-spin level scheme to the lower-spin states observed from the {beta} decay of {sup 134}Sm. Electron-conversion analysis for the 71-keV {gamma}-ray transition reveals that it is of E1 character and its small reduced-transition probability suggests that {sup 134}Pm may have a nuclear shape more rigid than that of the neighboring nuclei.
Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation
Schoeller, D.A.; Leitch, C.A.; Brown, C.
1986-12-01
The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO/sub 2/ excretion. To characterize in vivo isotope fractionation, we collected and isotopically analyzed physiological fluids and gases. Breath and transcutaneous water vapor were isotopically fractionated. The degree of fractionation indicated that the former was fractionated under equilibrium control at 37/sup 0/C, and the latter was kinetically fractionated. Sweat and urine were unfractionated. By use of isotopic balance models, the fraction of water lost via fractionating routes was estimated from the isotopic abundances of body water, local drinking water, and dietary solids. Fractionated water loss averaged 23% (SD = 10%) of water turnover, which agreed with our previous estimates based on metabolic rate, but there was a systematic difference between the results based on O/sub 2/ and hydrogen. Corrections for isotopic fractionation of water lost in breath and (nonsweat) transcutaneous loss should be made when using labeled water to measure water turnover or CO/sub 2/ production.
VizieR Online Data Catalog: Doubly 13C-substituted ethyl cyanide (Margules+,
NASA Astrophysics Data System (ADS)
Margules, L.; Belloche, A.; Muller, H. S. P.; Motiyenko, R. A.; Guillemin, J.-C.; Garrod, R. T.; Menten, K. M.
2016-04-01
We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three doubly 13C-substituted isotopomers. The quantum numbers reach J~115 and Ka~35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations beyond 1000 GHz for strong to moderately weak transitions of either isotopomer. All three species are unambiguously detected in our ALMA data. The 12C/13C column density ratio of the isotopomers with one 13C atom to those with two 13C atoms is about 25. Ethyl cyanide is the second molecule after methyl cyanide for which isotopologues containing two 13C atoms have been securely detected in the interstellar medium. The model of our ethyl cyanide data suggests that we should be able to detect vibrational satellites of the main species up to at least v19=1 at 1130K and up to v13+v21=2 at 600K for the isotopologues with one 13C atom in our present ALMA data. Such satellites may be too weak to be identified unambiguously for isotopologues with two 13C atoms. (3 data files).
Jha, Amit K.; Hule, Rohan A.; Jiao, Tong; Teller, Sean S.; Clifton, Rodney J.; Duncan, Randall L.; Pochan, Darrin J.; Jia, Xinqiao
2009-01-01
We have created a new class of hyaluronic acid (HA)-based hydrogel materials with HA hydrogel particles (HGPs) embedded in and covalently cross-linked to a secondary network. HA HGPs with an average diameter of ∼900 nm and narrow particle size distribution were synthesized using a refined reverse micelle polymerization technique. The average mesh size of the HGPs was estimated to be approximately 5.5 to 7.0 nm by a protein uptake experiment. Sodium periodate oxidation not only introduced aldehyde groups to the particles but also reduced the average particle size. The aldehyde groups generated were used as reactive handles for subsequent cross-linking with an HA derivative containing hydrazide groups. The resulting macroscopic gels contain two distinct hierarchical networks (doubly cross-linked networks, DXNs): one within individual particles and another among different particles. Bulk gels (BGs) formed by direct mixing of HA derivatives with mutually reactive groups were included for comparison. The hydrogel microstructures were collectively characterized by microscopy and neutron scattering techniques. Their viscoelasticity was quantified at low frequencies (0.1−10 Hz) using a controlled stress rheometer and at high frequencies (up to 200 Hz) with a home-built torsional wave apparatus. Both BGs and DXNs are stable elastic gels that become stiffer at higher frequencies. The HA-based DXN offers unique structural hierarchy and mechanical properties that are suitable for soft tissue regeneration. PMID:20046226
Doubly differential single and multiple ionization of krypton by electron impact
Lucio, O. G. de; Gavin, J.; DuBois, R. D.
2007-05-15
Differential measurements for single and multiple ionization of Kr by 240 and 500 eV electron impact are presented. Using a pulsed extraction field, Kr{sup +}, Kr{sup 2+}, and Kr{sup 3+} ions were measured in coincidence with scattered electrons for energy losses up to 120 eV and scattering angles between 16 degree sign and 90 degree sign . Scaling properties of the doubly differential cross sections (DDCS) are investigated as a function of energy loss, scattering angle, and momentum transfer. It is shown that scaling the DDCS as outlined by Kim and Inokuti and plotting them versus a parameter consisting of the momentum transfer divided by the square root of the impact energy times 1-cos({theta}), where {theta} is the scattering angle, yielded similar curves, but with different magnitudes, for single and multiple ionization. Normalizing these curves together produced two universal curves, one appropriate for single and multiple electron emission at larger scattering angles ({theta}{>=}30 degree sign ) and one appropriate for small scattering angles ({theta}<30 degree sign )
Passamonti, Marco; Ghiselli, Fabrizio
2009-02-01
Eukaryotes have exploited several mechanisms for organelle uniparental inheritance, so this feature arose and evolved independently many times in their history. Metazoans' mitochondria commonly experience strict maternal inheritance; that is, they are only transmitted by females. However, the most noteworthy exception comes from some bivalve mollusks, in which two mitochondrial lineages (together with their genomes) are inherited: one through females (F) and the other through males (M). M and F genomes show up to 30% sequence divergence. This inheritance mechanism is known as doubly uniparental inheritance (DUI), because both sexes inherit uniparentally their mitochondria. Here, we review what we know about this unusual system, and we propose a model for evolution of DUI that might account for its origin as sex determination mechanism. Moreover, we propose DUI as a choice model to address many aspects that should be of interest to a wide range of biological subfields, such as mitochondrial inheritance, mtDNA evolution and recombination, genomic conflicts, evolution of sex, and developmental biology. Actually, as research proceeds, mitochondria appear to have acquired a central role in many fundamental processes of life, which are not only in their metabolic activity as cellular power plants, such as cell signaling, fertilization, development, differentiation, ageing, apoptosis, and sex determination. A function of mitochondria in the origin and maintenance of sex has been also proposed.
Spherical and Superdeformed Structures Near Doubly-Magic Nuclei ^40Ca, ^56Ni, and ^100Sn
NASA Astrophysics Data System (ADS)
Baktash, Cyrus
2000-11-01
For more than thirty years, shell model calculations have predicted that multiparticle-multihole excitations across magic numbers 8, 20 and 28 would lead to very deformed and superdeformed states in the vicinity of doubly-magic nuclei ^16O, ^40Ca, and ^16Ni. These expectations were later confirmed in various cluster and mean field calculations that predicted the existence of new islands of superdeformation centered around ^32S and ^60Zn. However, it was only recently that advances in detector technology have allowed exploration of these weakly-populated structures. In this talk, I will present results of our recent experiments that have succeeded in identifying these long-sought states and their exotic decay modes. These data have provided a unique testing ground to confront, compare, and relate state-of-the-art calculations in the framework of microscopic (large-scale shell models, Quantum Monte Carlo Diagonalization), and mean field theories. Highlights of these results, including a discussion of the importance of neutron-proton pairing correlations in these nearly N=Z nuclei will be discussed. * Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
Discovery of four doubly imaged quasar lenses from the Sloan digital sky survey
Inada, Naohisa; Oguri, Masamune; Rusu, Cristian E.; Kayo, Issha; Morokuma, Tomoki
2014-06-01
We report the discovery of four doubly imaged quasar lenses. All the four systems are selected as lensed quasar candidates from the Sloan Digital Sky Survey data. We confirm their lensing hypothesis with additional imaging and spectroscopic follow-up observations. The discovered lenses are SDSS J0743+2457 with the source redshift z{sub s} = 2.165, the lens redshift z{sub l} = 0.381, and the image separation θ = 1.''034, SDSS J1128+2402 with z{sub s} = 1.608 and θ = 0.''844, SDSS J1405+0959 with z{sub s} = 1.810, z{sub l} ≈ 0.66, and θ = 1.''978, and SDSS J1515+1511 with z{sub s} = 2.054, z{sub l} = 0.742, and θ = 1.''989. It is difficult to estimate the lens redshift of SDSS J1128+2402 from the current data. Two of the four systems (SDSS J1405+0959 and SDSS J1515+1511) are included in our final statistical lens sample to derive constraints on dark energy and the evolution of massive galaxies.
Cosmic Ray Diffusion Tensor Throughout the Heliosphere
NASA Astrophysics Data System (ADS)
Pei, C.; Bieber, J. W.; Breech, B.; Burger, R. A.; Clem, J.; Matthaeus, W. H.
2008-12-01
We calculate the cosmic ray diffusion tensor based on a recently developed model of magnetohydrodynamic (MHD) turbulence in the expanding solar wind [Breech et al., 2008.]. Parameters of this MHD model are tuned by using published observations from Helios, Voyager 2, and Ulysses. We present solutions of two turbulence parameter sets and derive the characteristics of the cosmic ray diffusion tensor for each. We determine the parallel diffusion coefficient of the cosmic ray following the method presented in Bieber et al. [1995]. We use the nonlinear guiding center (NLGC) theory to obtain the perpendicular diffusion coefficient of the cosmic ray [Matthaeus et al. 2003]. We find that (1) the radial mean free path decreases from 1 AU to 20 AU for both turbulence scenarios; (2) after 40 AU the radial mean free path is nearly constant; (3) the radial mean free path is dominated by the parallel component before 20 AU, after which the perpendicular component becomes important; (4) the rigidity P dependence of the parallel component of the diffusion tensor is proportional to P.404 for one turbulence scenario and P.374 for the other at 1 AU from 0.1 GVto 10 GV, but in the outer heliosphere its dependence becomes stronger above 4 GV; (5) the rigidity P dependence of the perpendicular component of the diffusion tensor is very weak. Supported by NASA Heliophysics Guest Investigator grant NNX07AH73G and by NASA Heliophysics Theory grant NNX08AI47G.
Nonlinear Analysis of Surface EMG Time Series of Back Muscles
NASA Astrophysics Data System (ADS)
Dolton, Donald C.; Zurcher, Ulrich; Kaufman, Miron; Sung, Paul
2004-10-01
A nonlinear analysis of surface electromyography time series of subjects with and without low back pain is presented. The mean-square displacement and entropy shows anomalous diffusive behavior on intermediate time range 10 ms < t < 1 s. This behavior implies the presence of correlations in the signal. We discuss the shape of the power spectrum of the signal.
NASA Astrophysics Data System (ADS)
Bao, Jing-Dong; Liu, Jian
2013-08-01
We consider anomalous diffusion of a particle moving in a tilted periodic potential in the presence of Lévy noise and nonlinear friction. Using Monte Carlo simulations, we have found some interesting characteristics of diffusion in such a nonlinear system: when the noise intensity is weak and the external force is close to the critical value at which local minima of the potential just vanish, the nonmonotonic behavior of the effective diffusion index and the superballistic diffusion are observed. This is due to the bimodal nature of the velocity distribution, and thus the test particles exist in either a running state or a long-tailed behind state in the spatial coordinate; the latter is disintegrated into small pieces of the probability peaks. We provide a relation between the group diffusion coefficient and the phase diffusion coefficient. It is shown that the distance between the above two-state centers increasing with time plays the definitive role in the superballistic group diffusion.
Zweig, George
2016-05-01
An earlier paper characterizing the linear mechanical response of the organ of Corti [J. Acoust. Soc. Am. 138, 1102-1121 (2015)] is extended to the nonlinear domain. Assuming the existence of nonlinear oscillators nonlocally coupled through the pressure they help create, the oscillator equations are derived and examined when the stimuli are modulated tones and clicks. The nonlinearities are constrained by the requirements of oscillator stability and the invariance of zero crossings in the click response to changes in click amplitude. The nonlinear oscillator equations for tones are solved in terms of the fluid pressure that drives them, and its time derivative, presumably a proxy for forces created by outer hair cells. The pressure equation is reduced to quadrature, the integrand depending on the oscillators' responses. The resulting nonlocally coupled nonlinear equations for the pressure, and oscillator amplitudes and phases, are solved numerically in terms of the fluid pressure at the stapes. Methods for determining the nonlinear damping directly from measurements are described. Once the oscillators have been characterized from their tone and click responses, the mechanical response of the cochlea to natural sounds may be computed numerically. Signal processing inspired by cochlear mechanics opens up a new area of nonlocal nonlinear time-frequency analysis.
Zweig, George
2016-05-01
An earlier paper characterizing the linear mechanical response of the organ of Corti [J. Acoust. Soc. Am. 138, 1102-1121 (2015)] is extended to the nonlinear domain. Assuming the existence of nonlinear oscillators nonlocally coupled through the pressure they help create, the oscillator equations are derived and examined when the stimuli are modulated tones and clicks. The nonlinearities are constrained by the requirements of oscillator stability and the invariance of zero crossings in the click response to changes in click amplitude. The nonlinear oscillator equations for tones are solved in terms of the fluid pressure that drives them, and its time derivative, presumably a proxy for forces created by outer hair cells. The pressure equation is reduced to quadrature, the integrand depending on the oscillators' responses. The resulting nonlocally coupled nonlinear equations for the pressure, and oscillator amplitudes and phases, are solved numerically in terms of the fluid pressure at the stapes. Methods for determining the nonlinear damping directly from measurements are described. Once the oscillators have been characterized from their tone and click responses, the mechanical response of the cochlea to natural sounds may be computed numerically. Signal processing inspired by cochlear mechanics opens up a new area of nonlocal nonlinear time-frequency analysis. PMID:27250151
Turing space in reaction-diffusion systems with density-dependent cross diffusion
NASA Astrophysics Data System (ADS)
Zemskov, E. P.; Kassner, K.; Hauser, M. J. B.; Horsthemke, W.
2013-03-01
Reaction-diffusion systems with cross-diffusion terms that depend linearly on density are studied via linear stability analysis and weakly nonlinear analysis. We obtain and analyze the conditions for the Turing instability and derive a universal form of these conditions. We discuss the features of the pattern-forming regions in parameter space for a cross activator-inhibitor system, the Brusselator model, and for a pure activator-inhibitor system, the two-variable Oregonator model. The supercritical or subcritical character of the Turing bifurcation for the Brusselator is determined by deriving an amplitude equation for patterns near the instability threshold.
Nonlinear ordinary difference equations
NASA Technical Reports Server (NTRS)
Caughey, T. K.
1979-01-01
Future space vehicles will be relatively large and flexible, and active control will be necessary to maintain geometrical configuration. While the stresses and strains in these space vehicles are not expected to be excessively large, their cumulative effects will cause significant geometrical nonlinearities to appear in the equations of motion, in addition to the nonlinearities caused by material properties. Since the only effective tool for the analysis of such large complex structures is the digital computer, it will be necessary to gain a better understanding of the nonlinear ordinary difference equations which result from the time discretization of the semidiscrete equations of motion for such structures.
Martin, G; McGarel, S
2001-01-01
A mill is a mechanical device that grinds mined or processed material into small particles. The process is known to display significant deadtime, and, more notably, severe nonlinear behavior. Over the past 25 years attempts at continuous mill control have met varying degrees of failure, mainly due to model mismatch caused by changes in the mill process gains. This paper describes an on-line control application on a closed-circuit cement mill that uses nonlinear model predictive control technology. The nonlinear gains for the control model are calculated on-line from a neural network model of the process.
Multipole nonlinearity of metamaterials
Petschulat, J.; Chipouline, A.; Tuennermann, A.; Pertsch, T.; Menzel, C.; Rockstuhl, C.; Lederer, F.
2009-12-15
We report on the linear and nonlinear optical response of metamaterials evoked by first- and second-order multipoles. The analytical ground on which our approach is based permits for new insights into the functionality of metamaterials. For the sake of clarity we focus here on a key geometry, namely, the split-ring resonator, although the introduced formalism can be applied to arbitrary structures. We derive the equations that describe linear and nonlinear light propagation where special emphasis is put on second-harmonic generation. This contribution basically aims at stretching versatile and existing concepts to describe light propagation in nonlinear media toward the realm of metamaterials.
Diffusion bonding aeroengine components
NASA Astrophysics Data System (ADS)
Fitzpatrick, G. A.; Broughton, T.
1988-10-01
The use of diffusion bonding processes at Rolls-Royce for the manufacture of titanium-alloy aircraft engine components and structures is described. A liquid-phase diffusion bonding process called activated diffusion bonding has been developed for the manufacture of the hollow titanium wide chord fan blade. In addition, solid-state diffusion bonding is being used in the manufacture of hollow vane/blade airfoil constructions mainly in conjunction with superplastic forming and hot forming techniques.
Updating applied diffusion models
Weil, J.C.
1985-11-01
Most diffusion models currently used in air quality applications are substantially out of date with understanding of turbulence and diffusion in the planetary boundary layer. Under a Cooperative Agreement with the Environmental Protection Agency, the American Meteorological Society organized a workshop to help improve the basis of such models, their physics and hopefuly their performance. Reviews and recommendations were made on models in three areas: diffusion in the convective boundary layer (CBL), diffusion in the stabe boundary layer (SBL), and model uncertainty.
Nonlinear parallel momentum transport in strong electrostatic turbulence
Wang, Lu Wen, Tiliang; Diamond, P. H.
2015-05-15
Most existing theoretical studies of momentum transport focus on calculating the Reynolds stress based on quasilinear theory, without considering the nonlinear momentum flux-〈v{sup ~}{sub r}n{sup ~}u{sup ~}{sub ∥}〉. However, a recent experiment on TORPEX found that the nonlinear toroidal momentum flux induced by blobs makes a significant contribution as compared to the Reynolds stress [Labit et al., Phys. Plasmas 18, 032308 (2011)]. In this work, the nonlinear parallel momentum flux in strong electrostatic turbulence is calculated by using a three dimensional Hasegawa-Mima equation, which is relevant for tokamak edge turbulence. It is shown that the nonlinear diffusivity is smaller than the quasilinear diffusivity from Reynolds stress. However, the leading order nonlinear residual stress can be comparable to the quasilinear residual stress, and so may be important to intrinsic rotation in tokamak edge plasmas. A key difference from the quasilinear residual stress is that parallel fluctuation spectrum asymmetry is not required for nonlinear residual stress.
ERIC Educational Resources Information Center
McCutcheon, James R.; Sanders, John R.
A methodology is presented for planning and managing the spread of educational innovations. The first portion of the guide develops a theoretical framework for diffusion which summarizes and capitalizes on the latest marketing and on the latest marketing and diffusion research findings. Major stages in the diffusion paradigm discussed include…