arXiv subjects

Yongbo Deng

Publications and source records attributed to Yongbo Deng.

10 recordsLinked to original sources

arXiv2026

Topology optimization of low-temperature type-II superconductors with superconductor-dielectric/vacuum interfaces based on Ginzburg-Landau theory under Weyl gauge

Geometrical design is a crucial and challenging strategy for improving the performance of type-II superconductors, because the proper placement of intended defects in the current path contribute to flux pinning, a reduction in dissipation, and an increase in achievable current density. Topology optimization is currently one of the most powerful approaches used to determine consistent structural geometries. Therefore, a topology optimization approach is presented to inversely design structural geometries of low-temperature type-II superconductors with superconductor-dielectric/vacuum interfaces.

cond-mat.supr-con↗

arXiv2025

Finite elements and moving asymptotes accelerate quantum optimal control -- FEMMA

Quantum optimal control is central to designing spin manipulation pulses. Gradient-based pulse optimization can be facilitated by either accelerating gradient evaluation or enhancing the convergence rate. In this work, we accelerated single-spin optimal control by combining the finite element method with the method of moving asymptotes. By treating discretized time as spatial coordinates, the Liouville - von Neumann equation was reformulated as a linear system, efficiently yielding a joint solution of the spin trajectory and control gradient. The method of moving asymptotes, relying on the ensemble fidelities and gradients, achieves rapid convergence for a target fidelity of 0.995.

physics.chem-ph↗

arXiv2024

Fiber bundle topology optimization for mass and heat transfer in laminar flow

This paper presents fiber bundle topology optimization for mass and heat transfer in surface and volume flow in the laminar region, to optimize the matching between the pattern of a surface structure and the implicit 2-manifold on which the pattern is defined. The fiber bundle concept is used to describe the pattern of the surface structure together with the implicit 2-manifold as an ensemble defined on the preset base manifold. Topology optimization of the surface structure for mass and heat transfer in surface and volume flow is then implemented on the variable curved surface expressed as the implicit 2-manifold, which is defined on the preset base manifold by using a differentiable homeomorphism. For both of the surface and volume flow, two sets of design variables are defined for the pattern of the surface structure and the implicit 2-manifold. The fiber bundle topology optimization problems are analyzed by using the continuous adjoint method to derive the gradient information of the design objectives and constraints, and they are then solved by using the gradient based iterative procedures. In the numerical results, the effects of variable amplitude of the implicit 2-manifold, Reynolds number, Péclet number, and pressure drop or dissipation power of the fluid flow are investigated to demonstrate the extended design freedom and design space of fiber bundle topology optimization for mass and heat transfer in surface and volume flow.

physics.flu-dyn↗

arXiv2024

Data-driven Topology Optimization of Channel Flow Problems

Typical topology optimization methods require complex iterative calculations, which cannot meet the requirements of fast computing applications. The neural network is studied to reduce the time of computing the optimization result, however, the data-driven method for fluid topology optimization is less of discussion. This paper intends to introduce a neural network architecture that avoids time-consuming iterative processes and has a strong generalization ability for topology optimization for Stokes flow. Different neural network methods including Convolution Neural Networks (CNN), conditional Generative Adversarial Networks (cGAN), and Denoising Diffusion Implicit Models (DDIM) which have been already successfully used in solid structure optimization problems are mutated and examined for fluid topology optimization cases. The presented neural network method is tested on the channel flow topology optimization problems for Stokes flow. The results have shown that our presented method has high pixel accuracy and gains a 663 times decrease on average in execution time compared with the conventional method.

physics.comp-ph↗

arXiv2022

Fiber bundle topology optimization for surface flows

This paper presents a topology optimization approach for the surface flows on variable design domains. Via this approach, the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized, where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base manifold. The fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber bundle. The material distribution method is used to achieve the evolution of the pattern of the surface flow. The evolution of the implicit 2-manifold is realized via a homeomorphous map. The design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE filters. The two surface-PDE filters are coupled, because they are defined on the implicit 2-manifold and base manifold, respectively. The surface Navier-Stokes equations, defined on the implicit 2-manifold, are used to describe the surface flow. The fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev space. Several numerical examples have been provided to demonstrate this approach, where the combination of the viscous dissipation and pressure drop is used as the design objective.

math.OC↗

arXiv2020

Topology optimization of surface flows

This paper presents a topology optimization approach for surface flows, which can represent the viscous and incompressible fluidic motions at the solid/liquid and liquid/vapor interfaces. The fluidic motions on such material interfaces can be described by the surface Navier-Stokes equations defined on 2-manifolds or two-dimensional manifolds, where the elementary tangential calculus is implemented in terms of exterior differential operators expressed in a Cartesian system. Based on the topology optimization model for fluidic flows with porous medium filling the design domain, an artificial Darcy friction is added to the area force term of the surface Navier-Stokes equations and the physical area forces are penalized to eliminate their existence in the fluidic regions and to avoid the invalidity of the porous medium model. Topology optimization for steady and unsteady surface flows can be implemented by iteratively evolving the impermeability of the porous medium on the 2-manifolds, where the impermeability is interpolated by the material density derived from a design variable. The related partial differential equations are solved by using the surface finite element method. Numerical examples have been provided to demonstrate this topology optimization approach for surface flows, including the boundary velocity driven flows, area force driven flows and convection-diffusion flows.

physics.comp-ph↗

arXiv2019

Topology optimization on two-dimensional manifolds

This paper implements topology optimization on two-dimensional manifolds. In this paper, the material interpolation is implemented on a material parameter in the partial differential equation used to describe a physical field, when this physical field is defined on a two-dimensional manifold; the material density is used to formulate a mixed boundary condition of the physical field and implement the penalization between two different types of boundary conditions, when this physical field is defined on a three-dimensional domain with its boundary conditions defined on the two-dimensional manifold corresponding a surface or an interface of this three-dimensional domain. Based on the homeomorphic property of two-dimensional manifolds, typical two-dimensional manifolds, e.g., sphere, torus, Möbius strip and Klein bottle, are included in the numerical tests, which are provided for the problems on fluidic mechanics, heat transfer and electromagnetics.

physics.comp-ph↗

arXiv2017

Inverse design of resonant nanostructures for extraordinary optical transmission of periodic metallic slits

This paper has presented inversely determining the resonant configuration of the bilateral nanostructures for periodic metallic slits with extraordinary optical transmission performance. The topology optimization approach is utilized to implement the inverse design procedure. Several geometrical configurations of the bilateral nanostructures are derived for periodic metallic slits. The resonant performance of the derived nanostructures are demonstrated by the transmission spectra, where the transmission peak is presented at the specified wavelength in the inverse design procedure. This provides an approach to control the red or blue shift of the transmission peak or localize the resonant performance at a desired frequency, by specifying the desired incident wavelength in the inverse design procedure. The inverse design method is extended to make the periodic metallic slits to be less sensitive to the incident wavelength. This research can be further extended to inversely find the resonant subwavelength structures for extraordinary optical absorption and other surface palsmon polariton based photonic devices. The inverse design of three dimensional apertures for extraordinary optical transmission will be investigated in our future researches.

physics.optics↗

arXiv2017

Inverse design method for metalens with optical vortices towards light focusing through localized phase retardation

Metalenses can achieve diffraction-limited focusing through localized phase manipulation of the incoming light beam. Because these structures are ultrathin, less than a wavelength, this has the potential of achieving ultrathin optical elements, with a thickness limited mainly by the mechanical strength of the transparent substrate. Recently proposed metalenses are based on either dielectric nanofin arrays, or nanoparticles of large number, which leads to severe manufacturing challenges. To overcome these challenges, this paper predicts a new type of metalens with concentric-nanoring topology, where the number and size of the nanorings are determined using an inverse design method. By focusing the electrical field energy at a specified position, the convex-like metalens is inversely predicted with desired numerical aperture and a diffraction-limited focal spot. The Poynting vector distribution found demonstrates the mechanism of the lensing function, in which optical vortices are generated in the nanorings to achieve a matching of the phase and impedance between the substrate and free space, and further, to form a spherical wavefront and enhance the transmission of the optical energy. The inverse design method can also be extended to predict an axicon-like metalens with focal beam. The improved manufacturability is concluded from the geometry of the concentric-nanoring configurations.

physics.optics↗

arXiv2017

Optimal control-based inverse determination of electrode distribution for electroosmotic micromixer

This paper presents an optimal control-based inverse method used to determine the distribution of the electrodes for the electroosmotic micromixers with external driven flow from the inlet. Based on the optimal control method, one Dirichlet boundary control problem is constructed to inversely find the optimal distribution of the electrodes on the sidewalls of electroosmotic micromixers and achieve the acceptable mixing performance. After solving the boundary control problem, the step-shaped distribution of the external electric potential imposed on the sidewalls can be obtained and the distribution of electrodes can be inversely determined according to the obtained external electric potential. Numerical results are also provided to demonstrate the effectivity of the proposed method.

physics.flu-dyn↗