Article
Computer Science, Interdisciplinary Applications
Xiangcou Zheng, Feng Yang
Summary: This study presents an efficient and robust adaptive remeshing strategy in kinematic upper-bound limit analysis using six-node triangular elements and Second-Order Cone Programming. The proposed method, UBFEM-SMRC, demonstrates more rigorous solutions and significantly reduces computational burdens compared to the Pure Mesh Refinement scheme. The synchronous adaptive mesh refining-coarsening process results in clearer adaptively refined mesh zones with intensive plastic dissipations, which can accurately reproduce potential failure mechanisms of geotechnical problems.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Optics
Chaohan Cui, William Horrocks, Shuhong Hao, Saikat Guha, Nasser Peyghambarian, Quntao Zhuang, Zheshen Zhang
Summary: This study presents a general architecture of a quantum receiver enhanced by adaptive learning, which is capable of adapting to different operational conditions. The adaptively learned quantum receiver is experimentally implemented with record-high efficiency. The experimental results show that the error rate is reduced up to 40% in two coherent-state encoding schemes.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Computer Science, Artificial Intelligence
Xinze Li, Kezhi Mao, Fanfan Lin, Xin Zhang
Summary: PSO-SAVL is a novel variant of PSO with state-based adaptive velocity limit strategy, which shows good performance in avoiding local optima and scalability in high dimensions and large-scale problems. The merits of the strategies in PSO-SAVL are verified in experiments, and sensitivity analysis for the relevant hyper-parameters in state-based adaptive VL strategy provides insights on how to select these hyper-parameters.
Article
Computer Science, Information Systems
Jonathan Lacotte, Mert Pilanci
Summary: We propose novel randomized optimization methods for high-dimensional convex problems based on restrictions of variables to random subspaces. We consider oblivious and data-adaptive subspaces and study their approximation properties via convex duality and Fenchel conjugates. A suitable adaptive subspace can be generated by sampling a correlated random matrix whose second order statistics mirror the input data. We show that the relative error of the randomized approximations can be tightly characterized in terms of the spectrum of the data matrix and Gaussian width of the dual tangent cone at optimum. Experimental results show that the proposed approach enables significant speed ups in a wide variety of machine learning and optimization problems.
IEEE TRANSACTIONS ON INFORMATION THEORY
(2022)
Article
Computer Science, Interdisciplinary Applications
Canh Le, Phuc L. H. Ho, Huy T. Ly, Thanh T. Nguyen, Phuong H. Nguyen
Summary: This paper presents a pseudo-lower bound numerical procedure for adaptive limit analysis of geo-mechanics problems governed by the Mohr-Coulomb failure criterion, without the need for stress-based elements. The non-linear failure criterion is converted into a standard conic constraint form for efficient solver use, while adaptive mesh refinement based on a refinement indicator accelerates the computational progress.
COMPUTERS AND GEOTECHNICS
(2021)
Article
Physics, Mathematical
Nicholas Fleming-Vazquez
Summary: This study proves optimal moment bounds for a nonuniformly hyperbolic map in certain ranges, utilizing abstract functional correlation bounds and weak dependence arguments. The results are significant in proving deterministic homogenisation results using rough path theory. Additionally, recent findings demonstrate convergence to an Ito diffusion for fast-slow systems in the optimal range beta > 2.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2022)
Article
Engineering, Civil
Rui Zhang, Gaoqiao Wu, Minghua Zhao, Ming Lei
Summary: This study investigated the undrained seismic stability of dual unsupported circular tunnels using an adaptive finite element limit analysis. Parametric studies and visualized results showed the significant impact of seismic effects on tunnel stability and failure mechanisms.
INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS
(2021)
Article
Quantum Science & Technology
Anurag Anshu, Tony Metger
Summary: We prove concentration bounds for shallow quantum circuits, injective matrix product states, and output states of dense Hamiltonian evolution. Our proofs show that these states are close to local operators, implying concentration of the Hamming weight of computational basis measurements. We apply these concentration results to limit the success probability of the quantum approximate optimization algorithm on dense instances.
Article
Optics
Kurt Schab, Lukas Jelinek, Miloslav Capek, Mats Gustafsson
Summary: Upper bounds on the focusing efficiency of aperture fields and lens systems are proposed using integral equation representations of Maxwell's equations and Lagrangian duality. Two forms of focusing efficiency based on lens exit plane fields and optimal polarization currents are considered. The bounds are compared with classical prescriptions and inverse design lenses, showing that unbounded focusing efficiency can be achieved with lens exit plane fields. Additionally, aperture fields based on time-reversal do not necessarily yield optimal lens focusing efficiency in near-field focusing.
Article
Computer Science, Interdisciplinary Applications
Jeet Desai, Gregoire Allaire, Francois Jouve
Summary: In this study, a topology optimization algorithm based on the level-set method is proposed for the design of linear elastic structures considering fractures. The brittle fracture is modeled using the Francfort-Marigo energy model, which incorporates the Ambrosio-Tortorelli regularization for gradient damage. A penalization method is employed to approximate the quasi-static and irreversible gradient damage model for shape-differentiation. The shape derivative is computed using the adjoint method. Numerical implementation of shape optimization is performed using the level-set method with body-fitted remeshing to accurately capture shapes and allow for topology changes. Numerical tests demonstrate the efficiency of the proposed method in designing crack-free structures.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Emidio Gabrielli, Barbara Mele, Roberto Onofrio
Summary: Exploring flavor violations in the charged-lepton sector through high-luminosity lepton-photon and electron-muon collisions by inverting initial and final states in various decay channels. Analyzing resonant lepton and neutral-meson scattering channels critically dependent on beam energy spread, with upper bounds computed for these processes. Extending analysis to processes with accompanying photons to compensate off-shellness effects, which may be studied at future facilities with sufficiently high luminosity.
Article
Engineering, Multidisciplinary
Yufei Guo, Yongqing Hai
Summary: The paper introduces a method of triangular mesh remeshing based on sphere packing and node insertion/deletion, which can generate high-quality meshes without depending on the quality of the original mesh. The optimized mesh does not require complicated calculations, making the method efficient and effective.
APPLIED MATHEMATICAL MODELLING
(2021)
Article
Engineering, Geological
Jim Shiau, Van Qui Lai, Suraparb Keawsawasvong
Summary: This study investigates the three-dimensional undrained slopes in anisotropic and heterogenous clay using advanced finite element limit analysis. The stability solutions are presented by a stability number that is a function of geometrical and material ratios. Numerical results are compared with experimental data and charts are provided for a wide range of design parameters. The influence and sensitivity of each design parameter on the stability number and failure mechanism are analyzed using multivariate adaptive regression splines. An empirical equation is also developed for estimating the stability number effectively.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Computer Science, Interdisciplinary Applications
Phuc L. H. Ho, Canh Le, Phuong H. Nguyen
Summary: This paper introduces two simple and efficient indicators for adaptive mesh refinement in limit state analysis of reinforced concrete slabs. The optimal layout of elements accurately computes the upper and pseudo-lower bounds on the collapse load factors, minimizing computational effort. Important information for slab design, such as plastic dissipation distribution and moment fields at limit state, is also provided.
STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION
(2022)
Article
Energy & Fuels
Jielin Luo, Guangming Chen, Qin Wang, Shaozhi Zhang
Summary: This paper investigates the upper limit of ejector performance by constructing an ideal ejector and thermodynamically optimizing its working process to achieve minimal entropy generation. The analytical solutions for optimal mixing pressure and maximal entrainment ratio are deduced for ideal gas working conditions. The thermodynamic upper limits provided in this study offer a more reasonable benchmark for evaluating ejector performance compared to previous models.
Review
Computer Science, Interdisciplinary Applications
Matteo Giacomini, Ruben Sevilla, Antonio Huerta
Summary: This paper introduces HDGlab, an open source MATLAB implementation of the hybridisable discontinuous Galerkin (HDG) method, with the goal of providing a detailed description of the HDG method and its implementation in HDGlab. HDGlab offers unique features not found in other implementations, such as high-order polynomial shape functions and support for curved isoparametric simplicial elements, making it a valuable tool for the computational engineering community.
ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING
(2021)
Review
Computer Science, Interdisciplinary Applications
Jordi Vila-Perez, Matteo Giacomini, Ruben Sevilla, Antonio Huerta
Summary: This paper presents a review of high-order hybridisable discontinuous Galerkin (HDG) methods for compressible flows and introduces an original unified framework for the derivation of Riemann solvers in hybridised formulations. HLL and HLLEM Riemann solvers demonstrate superiority in boundary layer approximation and positivity preservation, respectively, while the HDG scheme with artificial viscosity shock treatment technique shows competitiveness with traditional solvers.
ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Javier Bonet, Chun Hean Lee, Antonio J. Gil, Ataollah Ghavamian
Summary: This paper presents a computational framework for the numerical analysis of large strain dynamics and thermo-elastic systems, incorporating constitutive laws, polyconvexity considerations, and hyperbolicity analysis. The research extends to different elastic models and introduces a generalized convex entropy function. Additionally, a stabilised Petrov-Galerkin framework is proposed for the numerical solution of the thermo-elastic system, with various numerical examples provided to assess the formulation's applicability and robustness.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Mathematics, Interdisciplinary Applications
Kenny W. Q. Low, Chun Hean Lee, Antonio J. Gil, Jibran Haider, Javier Bonet
Summary: This paper introduces a new Smooth Particle Hydrodynamics computational framework for solving inviscid free surface flow problems. The method is based on Total Lagrangian description and introduces Riemann-based numerical dissipation for stability. A novel technique is used to demonstrate global numerical entropy production in terms of the time rate of the system's Hamiltonian. Through tests on dedicated prototype problems, the efficiency and stability of the SPH method are demonstrated.
COMPUTATIONAL PARTICLE MECHANICS
(2021)
Article
Materials Science, Multidisciplinary
Javier Bonet, Antonio J. Gil
Summary: This paper presents mathematical models of supersonic and intersonic crack propagation exhibiting Mach type of shock wave patterns that closely resemble experimental and computational evidence. The models are developed in the form of weak discontinuous solutions of the equations of motion for isotropic linear elasticity in two dimensions, showing the necessary requirements for their existence.
INTERNATIONAL JOURNAL OF FRACTURE
(2021)
Article
Mathematics, Applied
Matteo Giacomini, Luca Borchini, Ruben Sevilla, Antonio Huerta
Summary: This work compares the performance of a priori and a posteriori proper generalised decomposition algorithms for an incompressible Stokes flow problem in a geometrically parametrised domain, which is challenging due to the impact of geometric parameters on the solution manifold and computational spatial domain.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2021)
Article
Biology
Malik A. Dawi, Jose J. Munoz
Summary: Cells and tissues exhibit sustained oscillatory deformations during various processes, and a rheological model incorporating elastic, viscous, and frictional components has been proposed to generate oscillatory response. Increasing friction with the substrate disrupts the oscillatory response, while increasing stiffness stabilizes it. Additionally, extending the model with nonlinear deformation measures can produce sustained oscillations.
JOURNAL OF MATHEMATICAL BIOLOGY
(2021)
Article
Mechanics
Jose J. Munoz, Lucie Condamin, David Doste
Summary: This study investigates the motion of the contact surface centroid for contractile bodies on substrates with a viscous friction law and when inertial forces are negligible. A set of sufficient conditions are deduced to ensure that the surface centroid remains still, with additional conditions necessary in nonlinear analysis. The results demonstrate the inability of slender organisms to move under homogeneous viscous contact conditions if the contact surface remains constant, regardless of the contractility strategy employed.
MECHANICS RESEARCH COMMUNICATIONS
(2022)
Article
Engineering, Multidisciplinary
Paulo R. Refachinho J. de Campos, Antonio J. Gil, Chun Hean Lee, Matteo Giacomini, Javier Bonet
Summary: This paper presents a new Updated Reference Lagrangian Smooth Particle Hydrodynamics (SPH) algorithm for analyzing large deformation isothermal elasticity and elasto-plasticity. The formulation uses a suitable multiplicative decomposition of the conservation variables, leading to a simple set of equations with similarities to the conventional Total Lagrangian system. The paper also introduces a second-order entropy-stable SPH upwinding stabilization method and a three-stage Runge-Kutta time integration method to enhance stability. The methodology is demonstrated through a range of challenging problems, including benchmark three-dimensional large deformation elasto-plasticity problems. Novel expressions for evaluating kernels and gradients of kernels are explored to facilitate implementation.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Engineering, Multidisciplinary
Manuel A. Sanchez, Shukai Du, Bernardo Cockburn, Ngoc-Cuong Nguyen, Jaime Peraire
Summary: In this paper, several high-order accurate finite element methods for the Maxwell's equations are presented, which provide time-invariant, non-drifting approximations to the total electric and magnetic charges, and to the total energy. These methods are devised by taking advantage of the Hamiltonian structures of the Maxwell's equations and using spatial and temporal discretization techniques to ensure the conservation properties and convergence of the methods.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Computer Science, Interdisciplinary Applications
Jordi Vila-Perez, Matteo Giacomini, Ruben Sevilla, Antonio Huerta
Summary: This work introduces a face-centred finite volume (FCFV) method for simulating compressible flows. It provides first-order accurate approximations of conservative quantities without the need for gradient reconstruction, demonstrating strong adaptability in various flow scenarios.
COMPUTERS & FLUIDS
(2022)
Article
Cell Biology
Katerina Karkali, Prabhat Tiwari, Anand Singh, Sham Tlili, Ignasi Jorba, Daniel Navajas, Jose J. Munoz, Timothy E. Saunders, Enrique Martin-Blanco
Summary: During development, organs can achieve precise shapes and sizes not only through growth but also through condensation. A study on the embryonic ventral nerve cord (VNC) in Drosophila embryos reveals that the condensation process occurs through oscillatory contractions. The mechanical properties of the VNC vary spatially and temporally, and forces along its longitudinal axis are heterogeneous. This condensation process depends on the coordinated mechanical activities of neurons and glia, and can be explained by a viscoelastic model.
DEVELOPMENTAL CELL
(2022)
Article
Biology
Ester Comellas, Johanna E. Farkas, Giona Kleinberg, Katlyn Lloyd, Thomas Mueller, Timothy J. Duerr, Jose J. Munoz, James R. Monaghan, Sandra J. Shefelbine
Summary: Movement-induced forces are crucial for joint formation, but the mechanisms by which cells sense and respond to these mechanical cues are unclear. This study investigates the role of mechanical stimuli in shaping joints using experiments on regenerating axolotl forelimbs and a poroelastic model of bone rudiment growth. The results suggest that TRPV4 desensitization affects joint shape, and a computational model demonstrates that interstitial pressure driven by cyclic mechanical stimuli promotes local tissue growth, supporting our understanding of mechanobiology in joint morphogenesis.
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2022)
Article
Engineering, Multidisciplinary
Callum J. Runcie, Chun Hean Lee, Jibran Haider, Antonio J. Gil, Javier Bonet
Summary: This article presents a vertex-centered finite volume algorithm for explicit dynamic analysis of large strain contact problems. The algorithm utilizes a system of conservation equations and associated jump conditions to derive multiple dynamic contact models. It enforces both kinetic and kinematic contact interface conditions explicitly in the fluxes, and incorporates a shock capturing technique to improve algorithm performance near shocks. Additionally, global entropy production and stability are demonstrated. Numerical examples are provided to assess the algorithm's performance and applicability.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2022)
Article
Mechanics
Ashutosh Bijalwan, Jose J. Munoz
Summary: Optimal control theory is used to find the optimal input of a mechanical system modeled as an initial value problem. We propose time discretizations for direct midpoint (DMP) and indirect midpoint (IMP) algorithms, which result in different convergence orders for the adjoint variables. We also propose an indirect Hamiltonian-preserving (IHP) algorithm that preserves the control Hamiltonian and test these algorithms on various linear and nonlinear problems.
MULTIBODY SYSTEM DYNAMICS
(2023)
