Ease Of Convergence Research Articles

Performance of Various Length-to-Diameter Ratio of Thermal Energy Storage Tank: A Convergence Test

Thermal Energy Storage (TES) is a technique that stores thermal energy, accomplished by changing the temperature of a storage medium, such as a phase change material (PCM), for later use in various applications, for example, heating and cooling or power generation. The heat energy that is saved is usually kept in the storage medium. This study investigates how the performance of the TES tank is affected by the ratio of length to diameter. The research focuses on how the ratio affects the convergence test while the PCM0 (water-ice) used in TES starts to release latent heat into the air. Five models were designed by using CATIA software and the analysis was conducted in ANSYS CFD software. Convergence tests were conducted to validate the accuracy of the obtained simulation results. Two additional criteria, namely temperature and ice mass fraction, were also analysed to evaluate the performance of the TES tanks. The investigation of the TES tank using five different models has shown that each model reaches a constant temperature of 0°C during the melting phase, but at different time intervals. Model 1 reaches this temperature the fastest, followed by Model 2, Model 3, Model 4, and finally Model 5. A model that reached the constant temperature first indicated a more efficient discharging process, as it signified a faster rate of ice melting and thermal energy release. In terms of ice mass fraction, Model 1 retained a significant amount of solid ice (0.9968), with noticeable melting. Model 5, on the other hand, showed minimal melting and better preservation of solid ice (0.9992). Considering temperature, ice mass fraction and ease of convergence, Model 1 performed the best, when the solidified PCM0 was melting faster while maintaining a substantial amount of solid ice in the TES tank. The present study was successfully developed and compared various TES configurations while satisfying the convergence criteria set in the simulation. To conclude with, the results showcase the performance differences based on pipe size. These discoveries contribute to refining tube-type TES tanks and their design for thermal energy storage systems.

A simplified micro-model based on discrete elements and elastic bodies for non-linear static analysis of in-plane loaded masonry panels

A simplified micro-model based on discrete elements and elastic bodies for non-linear static analysis of in-plane loaded masonry panels

Ab initio calculation of electron-phonon linewidths and molecular dynamics with electronic friction at metal surfaces with numeric atom-centred orbitals

Molecular motion at metallic surfaces is affected by nonadiabatic effects and electron-phonon coupling. The ensuing energy dissipation and dynamical steering effects are not captured by classical molecular dynamics simulations, but can be described with the molecular dynamics with electronic friction method and linear response calculations based on density functional theory. Herein, we present an implementation of electron-phonon response based on an all-electron numeric atomic orbital description in the electronic structure code FHI-aims. After providing details of the underlying approximations and numerical considerations, we present significant scalability and performance improvements of the new code compared to a previous implementation (Maurer et al 2016 Phys. Rev. B 94 115432). We compare convergence behaviour and results of our simulations for exemplary systems such as H2 adsorption on Cu(111), and CO on Ru(0001) against existing plane wave implementations. We examine different expressions to calculate electronic friction and vibrational lifetimes for their reliability and ease of convergence. Finally, we show the capabilities of the new code by studying the contribution of interband and intraband excitations to the vibrational lifetime of aperiodic adsorbate motion in large, previously unfeasible, periodic surface models.

Topology optimization with local stress constraint based on level set evolution via reaction–diffusion

Abstract This work focuses the structural topology optimization problem of mass minimization subject to local stress constraints. To this aim, two related issues are addressed. The first one is the successful strategy used to define local stress constraints by means of an Augmented Lagrangian approach. The second, and main contribution of the present paper, is the use of a reaction–diffusion equation to guide, via evolution of a level set, the design optimization sequence. The advantages of this strategy are twofold: firstly, it allows the creation of new holes during the optimization process, a significant feature for a true topological optimization method. Secondly, reinitialization steps usually found in classical Hamilton–Jacobi based evolution are eliminated with a significant improvement in convergence ease. A set of benchmark examples in two dimensions are presented. Numerical results show the efficiency of the algorithm to create new holes, identify stress concentrations and to provide stable optimization sequences converging to local minima defined by stress saturated designs.

Multi structure morphological inpainting for the recovery of damaged digitised photographs

Multi structure morphological inpainting for the recovery of damaged digitised photographs is proposed. The motivation behind this paper is to address this interesting application area in terms of Morphological image processing literature and evaluate the interpolation capabilities of the same in the context of inpainting. As the inpainting order plays an important factor for human visualisation it is guided by the orientation of edges at the surrounding known regions of the missing domain. The damaged picture is edge detected by morphological gradient algorithm based on multi-structure element morphology of eight different directions. The edge detected image is represented as eight different edge planes based on the orientation of the edges. This edge plane information is used for reconstructing the regions within the missing part in a particular orientation, as well as for guiding the integration that follows. Edge planes having edges at the boundary of the missing domain are known as positive response edge planes. The damaged regions are morphologically eroded using the structuring elements of corresponding orientations given by the positive response edge planes. The resultant image is obtained using texture synthesis incorporated isotope driven integration of the eroded images. The novelty of our approach is to explicitly specify the direction of filling herby ensuring ease in convergence in different orientations and then streamlining the integration process to guarantee complete and natural look.

Fast Orientation-Driven Multi-Structure Morphological Inpainting

A fast inpainting algorithm for restoring damaged digitized photographs based on orientation-driven multistructure morphology is proposed. The inpainting is guided by the orientation of the edges at the known surrounding regions of the missing domain. The edges are grouped with respect to their orientation by compass operators. Each edge group is represented as separate plane. The edge-plane information is used twice manifold for reconstructing the regions within the missing part, as well as for guiding the integration that follows. The damaged regions are morphologically eroded using the structuring elements of corresponding orientations dictated by the edge planes. Simultaneously, the edge planes are interpolated. The resultant image is obtained by integrating the eroded images with reference to the interpolated edge planes. The novelty of our approach is to explicitly specify the direction of filling thereby ensuring ease in convergence in different orientations and then streamlining the process to guarantee complete and natural look. By implementing region-filling through morphological erosion, a non-iterative and non-sampling process makes the method faster than many traditional texture synthesis inpainting algorithms and successfully recovers images with better peak signal-to-noise ratios even for massive damages.

MULTIORIENTATION-BASED MULTISTRUCTURE MORPHOLOGICAL INPAINTING

A multiorientation-based multistructure morphological inpainting for the recovery of damaged digitized photographs is proposed. As the inpainting order plays a vital role for human visualization, the method is guided by the orientation of edges at the surrounding known regions of the missing (spoiled) domain. The damaged picture is decomposed into its constituent orientation subbands by steerable filters. The subband information is used for reconstructing the regions within the missing part at a particular orientation, as well as for guiding the integration of the reconstructed regions. Subbands having response at the boundary of the missing domain are named as constructive subbands. The damaged regions are morphologically eroded using the structuring elements of corresponding orientations that of the constructive subbands. The resultant image is obtained using winner-takes-all integration. The novelty of our approach is to explicitly specify the direction of filling thereby ensuring ease in convergence in different orientations and then streamlining the integration process to guarantee complete and natural look. Implementation of region-filling through morphological erosion, a noniterative and nonsampling process, makes the method faster than many other traditional texture synthesis inpainting algorithms and it successfully recovers images with better peak signal to noise ratios and structural similarity index even for massive damages.

Integral Equation Theory of Adsorption in Templated Materials: Influence of Molecular Attraction

Understanding the fundamental properties of fluids under confinement in templated porous media is important for the rational design of materials with tailored functions. However, theoretical descriptions remain elusive. Although a number of approaches have been developed within the replica Ornstein−Zernike (ROZ) formalism, they have thus far been limited mainly to simple species. Another challenge is associated with the general applicability of integral equation theories, originally developed for bulk liquids, to confined systems in general and, in particular, to molecular systems confined in templated structures. In this work, we extend our previous theory of molecular species adsorbed in a templated porous material (a ROZ solution to a reference interaction site model) to systems with attractive interactions. We explore the scope and applicability of direct routes toward the chemical potential in combination with several well-established closures, such as Percus−Yevick, mean spherical approximation, hypernetted chain closure (HNC), partially linearized HNC (PLHNC), and Martynov−Sarkisov. The relative accuracy, thermodynamic consistency, and ease of convergence are explored. Although only semiquantitative agreement can be expected from these approximate closure relations, we demonstrate that the proposed theory predicts templated molecular recognition with reasonable accuracy.