Search results for " Opera"

Positive solutions for singular double phase problems

2021

Abstract We study the existence of positive solutions for a class of double phase Dirichlet equations which have the combined effects of a singular term and of a parametric superlinear term. The differential operator of the equation is the sum of a p-Laplacian and of a weighted q-Laplacian ( q p ) with discontinuous weight. Using the Nehari method, we show that for all small values of the parameter λ > 0 , the equation has at least two positive solutions.

Integrability of the one dimensional Schrödinger equation

2018

We present a definition of integrability for the one dimensional Schroedinger equation, which encompasses all known integrable systems, i.e. systems for which the spectrum can be explicitly computed. For this, we introduce the class of rigid functions, built as Liouvillian functions, but containing all solutions of rigid differential operators in the sense of Katz, and a notion of natural boundary conditions. We then make a complete classification of rational integrable potentials. Many new integrable cases are found, some of them physically interesting.

Positivity, complex FIOs, and Toeplitz operators

2018

International audience; We establish a characterization of complex linear canonical transformations that are positive with respect to a pair of strictly plurisubharmonic quadratic weights. As an application, we show that the boundedness of a class of Toeplitz operators on the Bargmann space is implied by the boundedness of their Weyl symbols.

Some approximation properties by a class of bivariate operators

2019

WOS: 000503431300041

Stability of genetic regulatory networks with time-varying delay: Delta operator method

2015

This paper investigates the stability problem for a class of uncertain genetic regulatory networks (GRNs) with time-varying delay via delta operator approach. Both the parameter uncertainty and the generalized activations are considered in the model under study. By constructing an appropriate Lyapunov-Krasovskii functional, the stability and robust stability conditions of GRNs are presented under the delta operator frame. These conditions can be expressed in terms of linear matrix inequalities (LMIs). Finally, a numerical example is employed to illustrate the effectiveness of the proposed results.

On the zeros of Jacobi polynomials

1994

Producer's spatial equilibrium with a fuzzy constraint

1980

The classical theory of the producer’s equilibrium rests on two sets of particularly restrictive hypotheses. First it is implicitely assumed that all inputs and outputs are located in a single place where the producer is also implanted and where the production is carried out. Next it is assumed that the producer follows a precise behaviour pattern, by this we mean that the producer has complete information concerning the conditions of hisproductive activity and he has perfect command over both the set of inputs and the set of outputs; he realises the maximum profit allowed by the technological constraint which limits his possible actions and by the given price system. The aim of this study …

Maximum weight relaxed cliques and Russian Doll Search revisited

2015

Trukhanov et al. [Trukhanov S, Balasubramaniam C, Balasundaram B, Butenko S (2013) Algorithms for detecting optimal hereditary structures in graphs, with application to clique relaxations. Comp. Opt. and Appl., 56(1), 113–130] used the Russian Doll Search (RDS) principle to effectively find maximum hereditary structures in graphs. Prominent examples of such hereditary structures are cliques and some clique relaxations intensely discussed and studied in network analysis. The effectiveness of the tailored RDS by Trukhanov et al. for s-plex and s-defective clique can be attributed to their cleverly designed incremental verification procedures used to distinguish feasible from infeasible struct…

N-Isopropylacrylamide andN-Isopropylmethacryl-amide: Cloud Points of Mixtures and Copolymers

2001

The cloud point curve of aqueous solutions of poly(N-isopropylacrylamide), poly(N-isopropylmethacrylamide) and their statistical copolymers were determined turbidimetrically. All the Systems demix upon heating at the cloud point temperature and mix reversibly upon cooling. The cloud points are independent of the total concentration of the solutions (dilute range) and of the sample thickness. Mixtures of the homopolymers poly(N-isopropylacrylamide) and poly(N-isopropylmethacrylamide) in water (ternary systems) exhibit two cloud points, which are nearly the same as the cloud points of the two binary systems homopolymer/water. A quantitative correlation was found between the cloud point temper…

Phase diagrams of the system tetrahydrofuran/γ-butyrolactone/poly(ether imide) and determination of interaction parameters

1998

Abstract The thermodynamic interactions in the ternary mixture tetrahydrofuran/γ-butyrolactone/poly(ether imide) (THF/γ-BL/PEI) are investigated from 30 to 50°C. This is a membrane-forming system with a high He-selectivity. Cloud point measurements show that the two binary polymer solutions THF/PEI and γ-BL/PEI exhibit miscibility gaps which close towards the centre of the ternary phase diagram where the mixtures become homogeneous (cosolvency). Vapour pressures were determined for the subsystem THF/γ-BL. For the theoretical calculations the Gibbs energy of mixing is formulated according to the Flory-Huggins theory and the interaction parameter χ THF γ-BL calculated from the vapour pressure…