Search results for "efficient"

Diffraction by fractal metallic supergratings.

2007

The reflectance of corrugated surfaces with a fractal distribution of grooves is investigated. Triadic and polyadic Cantor fractal distributions are considered, and the reflected intensity is compared with that of the corresponding periodic structure. The self-similarity property of the response is analyzed when varying the depth of the grooves and the lacunarity parameter. The results confirm that the response is self-similar for the whole range of depths considered, and this property is also maintained for all values of the lacunarity parameter. © 2007 Optical Society of America. Fil: Skigin, Diana Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación…

Enhanced diffraction of light in GaAs microcavities

1995

We theoretically analyze the diffraction of light by gratings that are photogenerated in Fabry–Perot microcavities. The coupled-wave theory of volume gratings is combined with appropriate boundary conditions to yield expressions for the diffraction efficiency. Multiple round trips within the cavity are seen to increase the effective grating thickness and therefore the efficiency. Numerical calculations specific to GaAs microcavities show that the diffraction efficiency can be enhanced by more than 2 orders of magnitude at the resonant wavelengths.

Optimization of impurity profile for p-n junction in heterostructures

2005

We analyze the dopant diffusion in p-n-junction in heterostructure, by solving the diffusion equation with space-varying diffusion coefficient. For a step-wise spatial distribution we find the optimum annealing time to decrease the p-n-junction thickness and to increase the homogeneity of impurity concentration in p or n regions.

Diffusion, thermodiffusion, and thermal diffusion of polystyrene in solution

1962

ASSESMENT OF TEMPERATURE POLARIZATION IN MEMBRANE DISTILLATION CHANNELS BY LIQUID CRYSTAL THERMOGRAPHY

2014

AbstractThe measurement of local temperature distributions within a membrane distillation (MD) channel is a crucial step for the optimization of the channel and spacer geometry. This information allows the estimation of temperature polarization phenomena, which can dramatically influence the thermal efficiency of the process and the optimal choice of the geometric configuration (net spacer features, channel size, etc.). In the present work, a recently presented experimental technique, based on the use of thermochromic liquid crystals and digital image analysis, has been employed in order to assess the temperature polarization phenomena. The local heat transfer coefficient distribution on th…

A dynamic panel study on digitalization and firm's agility: What drives agility in advanced economies 2009–2018

2021

Abstract Firm agility today is not a factor of competitiveness or success but a survival instrument on the market. Disruptive innovations and technological advancement, together with digitalization, change the role of firm agility. We show that the link between the national/industry level of digitalization and firm agility is statistically robust and essential. We study the link on data from 2009 to 2018 in fifteen EU advanced economies using dynamic panel data modeling. The digitalization impact level differs across firms by ownership type (family to non-family firms). Agility in family firms is strongly influenced by the national/industry level of digitization and investments in intangibl…

An Efficient Algorithm for the Generation of Z-Convex Polyominoes

2014

We present a characterization of Z-convex polyominoes in terms of pairs of suitable integer vectors. This lets us design an algorithm which generates all Z-convex polyominoes of size n in constant amortized time.

Generalized Schröder permutations

2013

We give the generating function for the integer sequence enumerating a class of pattern avoiding permutations depending on two parameters: m and p. The avoided patterns are the permutations of length m with the largest element in the first position and the second largest in one of the last p positions. For particular instances of m and p we obtain pattern avoiding classes enumerated by Schroder, Catalan and central binomial coefficient numbers, and thus, the obtained two-parameter generating function gathers under one roof known generating functions and expresses new ones. This work generalizes some earlier results of Barcucci et al. (2000) [2], Kremer (2000) [5] and Kremer (2003) [6].

The Phagocyte Lattice of Dyck Words

2006

We introduce a new lattice structure on Dyck words. We exhibit efficient algorithms to compute meets and joins of Dyck words.

A loopless algorithm for generating the permutations of a multiset

2003

AbstractMany combinatorial structures can be constructed from simpler components. For example, a permutation can be constructed from cycles, or a Motzkin word from a Dyck word and a combination. In this paper we present a constructor for combinatorial structures, called shuffle on trajectories (defined previously in a non-combinatorial context), and we show how this constructor enables us to obtain a new loopless generating algorithm for multiset permutations from similar results for simpler objects.