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25362. Number of larval instars and sex-specific plasticity in the development of the small heath butterfly, Coenonympha pamphilus (Lepidoptera: Nymphalidae)
- Creator:
- García-Barros, Enrique
- Type:
- article, model:article, and TEXT
- Subject:
- Lepidoptera, butterfly, Satyrinae, Coenonympha, development, diapause, growth, head capsule, instar, moulting, phenotypic plasticity, and seasonality
- Language:
- English
- Description:
- The number of larval moults, larval head capsule width and pupal weight were investigated in both direct-developing and diapausing individuals of a South-West European population of Coenonympha pamphilus. The frequency distributions of head widths of successive larval instars overlapped, partly due to variation in the number of larval moults. The larvae that entered diapause went through five instars, instead of the four reported from this species. The evidence indicates that the five instar developmental pathway represents a plastic response rather than an example of compensatory growth. This alternative growth pattern was expressed in response to short photoperiods in parallel with, or as a consequence of, larval diapause. On average, the larvae with five instars had larger heads than their normal siblings. This resulted in comparatively heavier male pupae, while the opposite trend occurred in females. It is concluded that the variation in the number of larval instars is a plastic response to diapause when temperatures remain mild and that it might have an adaptive value in areas with mild winter climates. The sexually dimorphic expression in the larval growth patterns, in terms of pupal weight, may well imply different patterns of allocation of larval resources to adult structures, although sex-dependent differences in investment into purely larval structures cannot be discounted.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
25363. Numerical algorithms for perspective shape from shading
- Creator:
- Breuss, Michael, Cristiani, Emiliano, Durou, Jean-Denis, Falcone, Maurizio, and Vogel, Oliver
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- hypperbolic partial differential equation, Hamilton-Jacobi equation, finite difference method, semi-Lagrangian scheme, and Shape-From-Shading
- Language:
- English
- Description:
- The Shape-From-Shading (SFS) problem is a fundamental and classic problem in computer vision. It amounts to compute the 3-D depth of objects in a single given 2-D image. This is done by exploiting information about the illumination and the image brightness. We deal with a recent model for Perspective SFS (PSFS) for Lambertian surfaces. It is defined by a Hamilton-Jacobi equation and complemented by state constraints boundary conditions. In this paper we investigate and compare three state-of-the-art numerical approaches. We begin with a presentation of the methods. Then we discuss the use of some acceleration techniques, including cascading multigrid, for all the tested algorithms. The main goal of our paper is to analyze and compare recent solvers for the PSFS problem proposed in the literature.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
25364. Numerical analysis of a semi-implicit DDFV scheme for the regularized curvature driven level set equation in 2D
- Creator:
- Handlovičová, Angela and Kotorová, Dana
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- mean curvature flow, level set equation, numerical solution, semi-implicit scheme, discrete duality finite volume method, stavility, and convergence
- Language:
- English
- Description:
- Stability and convergence of the linear semi-implicit discrete duality finite volume (DDFV) numerical scheme in 2D for the solution of the regularized curvature driven level set equation is proved. Numerical experiments concerning comparison with exact solution and image filtering problem using proposed scheme are included.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
25365. Numerical and experimental modelling of turbulent flow in curved channels and diffusers
- Creator:
- Příhoda, Jaromír, Šulc, Jan, Sedlář, Milan, and Zubík, Pavel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- turbulent flow in curved channels and diffusers, numerical and experimental modelling, and computational fluid dynamics
- Language:
- English
- Description:
- Modelling of turbulent flow in curved channels and diffusers of rectangular cross-section was aimed at the evolution of secondary flow and origin of flow separation and their connection with energy losses and pressure recovery. Results of numerical simulations carried out using software CFX TASCflow 2.12 were compared with experiments made in a water channel. Turbulent flow in diffusers of rectangular cross-section with the constant channel height, flow turn angle 90 deg and area ratio AR = 1.5 was investigated. Numerical simulation was carried out for flow in diffusers with the cylindrical inner wall and with the cylindrical centreline. Turbulent flow in a curved channel of constant cross-section was investigated for comparison. Further, the effect of the inner wall radius on the character of flow in the diffuser was studied. Flow separation occurs on the inner wall of the channel before the bend exit and its extent is restricted to the central part of the channel due to secondary flow going from the sidewalls to the channel axis. The extent of separation region and consequently the energy losses decrease with the increasing radius of the inner wall curvature. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
25366. Numerical and experimental studies of laminar natural convection on a horizontal cylinder
- Creator:
- Švarc, Petr and Dvořák, Václav
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- natural convection, horizontal cylinder, Nusselt number, CFD, and measuring
- Language:
- English
- Description:
- This work with numerical and experimental studies of specific issues of natural convection flow around a horizontal cylinder in a space limited by rectangular cavity. Physical models of laminar unsteady flows have been used for numerical calculations of heat transfer coefficients of four different diameters of horizontal cylinders and for several temperature gradients. Procedures and results of the experimental studies are contained in the next section. All results were compared with different authors and different approaches, However the Nusselt numbers can be estimated due to the temperature interval, the results indicate need for further investigation. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
25367. Numerical insights into stress redistribution in protected seam mining with coal pillars and an application to methane control
- Creator:
- He , Fulian, Zhu , Ruojun, and Zhu , Hengzhong
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- protected seam mining, coal pillar, stress redistribution, methane control, and divisional management strategy
- Language:
- English
- Description:
- This paper identifies the stress redistribution of protected seams under the influence of coal pillars and a divisional management strategy for methane control. A coal pillar that is reserved in the protective seam greatly affects the abutment stress, the O-shaped circle’s evolution and the stress distribution. The strain-soften model was conducted using FLAC3D numerical analysis software to investigate the stress redistribution in the protected seam mining process. The results show that the abutment stress reaches a maximum value of 1.25 times the original stress when a protected seam coal face lies in the center of the coal pillar’s affected zone. The O-shaped circle is divided into two parts by the coal pillar, and its developmental width is closely associated with the protected seam mining stage and the developmental height of the “three zones”, especially the fractured zone. The stress redistribution of protected seam is rarely affected by the coal pillar when the distance is greater than 26 m. Both the total increased stress belt of the coal pillar affected zone and the total decreased stress belt of the other zones along the vertical direction significantly influence the methane migration. We propose a divisional management strategy that supplies a theoretical basis and technical guidance for methane control.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
25368. Numerical investigation of dynamic capillary pressure in two-phase flow in porous medium
- Creator:
- Fučík, Radek and Mikyška, Jiří
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- dynamic capillary pressure, two-phase flow in porous media, immiscible displacement in porous media, and finite volume method
- Language:
- English
- Description:
- In order to investigate effects of the dynamic capillary pressure-saturation relationship used in the modelling of a flow in porous media, a one-dimensional fully implicit numerical scheme is proposed. The numerical scheme is used to simulate an experimental procedure using a measured dataset for the sand and fluid properties. Results of simulations using different models for the dynamic effect term in capillary pressure-saturation relationship are presented and discussed.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
25369. Numerical methods for Markov chain models
- Creator:
- Mayer, Petr
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Markov chains and numerical method
- Language:
- English
- Description:
- We propose unified approach for analysis of finite discrete time Markov chains. We show some possibilities for computing stationary probabilty vectors even in the case of reducible transition matrix. Finally we show one method for computing of Mean First Passage Times Matrices. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
25370. Numerical modeling of the reinforcement corrosion of RC T-beam
- Creator:
- Koteš, Peter and Brodňan, Miroslav
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- reinforcement, corrosion, cracks, T-beam, numerical modeling, and concrete
- Language:
- English
- Description:
- The reinforcement corrosion is the phenomenon that highly affects the reliability and durability of reinforced concrete structures. From that reason, a lot of researchers in Slovakia and in the world pay their attention to reinforcement corrosion. In the frame of the research work, the reinforced concrete girder bridges were diagnosed and observed. These bridges are influenced by reinforcement corrosion of main girders. The paper is concerned with detection and simulation of corrosion of steel reinforcement in the reinforced concrete. The cracking response of the reinforced concrete beams due to the corrosion effect of the steel reinforcement was analyzed. The effect of corrosion was simulated by the nonlinear numerical analysis using the program ATENA - 2D and 3D module. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public