Search results for "High order"

On stability issues for IMEX schemes applied to 1D scalar hyperbolic equations with stiff reaction terms

2011

The application of a Method of Lines to a hyperbolic PDE with source terms gives rise to a system of ODEs containing terms that may have very different stiffness properties. In this case, Implicit-Explicit Runge-Kutta (IMEX-RK) schemes are particularly useful as high order time integrators because they allow an explicit handling of the convective terms, which can be discretized using the highly developed shock capturing technology, together with an implicit treatment of the source terms, necessary for stability reasons. Motivated by the structure of the source term in a model problem introduced by LeVeque and Yee in [J. Comput. Phys. 86 (1990)], in this paper we study the preservation of ce…

Fast Implementation of Double-coupled Nonnegative Canonical Polyadic Decomposition

2019

Real-world data exhibiting high order/dimensionality and various couplings are linked to each other since they share some common characteristics. Coupled tensor decomposition has become a popular technique for group analysis in recent years, especially for simultaneous analysis of multi-block tensor data with common information. To address the multiblock tensor data, we propose a fast double-coupled nonnegative Canonical Polyadic Decomposition (FDC-NCPD) algorithm in this study, based on the linked CP tensor decomposition (LCPTD) model and fast Hierarchical Alternating Least Squares (Fast-HALS) algorithm. The proposed FDCNCPD algorithm enables simultaneous extraction of common components, i…

A Polynomial Approach to the Piecewise Hyperbolic Method

2003

In this paper, a local (third-order accurate) shock capturing method for hyperbolic conservation laws is presented. The method has been made with the same idea as the PHM method, but with a simpler reconstruction. A comparison with the classic high order methods is discussed.

Produktintegration mit nicht-�quidistanten St�tzstellen

1980

For the numerical evaluation of $$\int\limits_a^b {(t - a)^{\alpha - 1} x(t)dt}$$ , 0<?<1 andx `smooth', product integration rules are applied. It is known that high-order rules, e.g. Gauss-Legendre quadrature, become `normal'-order rules in this case. In this paper it is shown that the high order is preserved by a nonequidistant spacing. Furthermore, the leading error terms of this product integration method and numerical examples are given.

Investigating the origin of parthenogenesis and ploidy level in Dahlica fennicella (Lepidoptera: Psychidae)

2013

The theories for the predominance of sexual reproduction predict that parthenogens should have no long-term evolutionary potential due to the lack of genetic recombination, despite short term advantages. Although parthenogenesis is rare among high order animals, true parthenogens can be found in various taxa. The intriguing question of the proliferation and persistence of parthenogenetic species needs investigation. An ideal species for such research is a parthenogenetic mont Dahlica fennicella that appears to be as equally successful as other coexisting sexual species. We investigated whether high ploidy level of D. fennnicella is due to hybridization between closely related sexual species…

High order normal form construction near the elliptic orbit of the Sitnikov problem

2011

We consider the Sitnikov problem; from the equations of motion we derive the approximate Hamiltonian flow. Then, we introduce suitable action–angle variables in order to construct a high order normal form of the Hamiltonian. We introduce Birkhoff Cartesian coordinates near the elliptic orbit and we analyze the behavior of the remainder of the normal form. Finally, we derive a kind of local stability estimate in the vicinity of the periodic orbit for exponentially long times using the normal form up to 40th order in Cartesian coordinates.

A method for the investigation of high-order two-frequency asynchronous oscillators

1992

A general method for analysing asynchronous high-order two-frequency oscillators is presented. the oscillator model is made up of a GC non-linear parallel group embedded in a linear lumped time-invariant network of any order. the approach devised rests on the identification of a pair of narrow-band impedance operators which permit one to derive first-approximation steady state and dynamic equations in the phasor domain—as well as stability criteria—in a simple and expressive manner. Previous results from averaging and perturbation treatments on fourth-order asynchronous oscillators are shown to be obtainable from this theory as particular cases. the sixth-order oscillator chosen as an appli…

Individuālu mīksto kontaktlēcu pielietojums acs aberāciju kompensācijai

2017

Darbs uzrakstīts angļu valodā uz 63 lapām. Tas satur 46 attēlus, 1 tabulu un 53 atsauces uz literatūras avotiem. Mērķis. Novērtēt agstāko kārtu aberāciju (HOA) ietekmi uz redzes funkcijām un acs optisko kvalitāti FOOT kontaktlēcu (KL) nēsātājiem. Metodes. Tika izmērīts redzes asums gadījumos (RA), kad acī ievietotas FOOT KL un parastās gāzu caurlaidīgās KL. Tika izmērītas visas aberācijas (TA) un HOA gadījumā, kad ievietotas abu veidu lēcas. Rezultāti. FOOT KL gadījumā RA bija tāds pats kā parasto KL gadījumā, vai augstāks (p<.01). FOOT KL gadījumā TA un HOA līmenis bija tāds pats kā parasto KL gadījumā, vai mazāks (p-value < .01). Secinājumi. FOOT KL sniedz augstāku RA nekā parastās KL un …

Study of the Effects of Nuclear Motion on High Harmonic Generation in Simple Molecules

2010

Measurement of high order Kerr refractive index of major air components: erratum

2010

A clarification is missing concerning the high order Kerr non-linearities deduced from our experimental data published in [Opt. Express 17, 13429-13434 (2009)]. Here, we rectify this omission by making explicit the distinction between cross-Kerr and Kerr effects, and by extrapolating the value of the nonlinear refractive index for the last effect. Since the occurrence of sign inversion in the Kerr effect is not affected, the overall report in [Opt. Express 17, 13429-13434] remains valid.