Youhei Akimoto

ORCID: 0000-0003-2760-8123
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About
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Research Areas
  • Metaheuristic Optimization Algorithms Research
  • Evolutionary Algorithms and Applications
  • Advanced Multi-Objective Optimization Algorithms
  • Neural Networks and Applications
  • Blind Source Separation Techniques
  • Maritime Navigation and Safety
  • Machine Learning and Data Classification
  • Topology Optimization in Engineering
  • Ship Hydrodynamics and Maneuverability
  • Advanced Neural Network Applications
  • Stochastic Gradient Optimization Techniques
  • Metamaterials and Metasurfaces Applications
  • Reservoir Engineering and Simulation Methods
  • Domain Adaptation and Few-Shot Learning
  • Face and Expression Recognition
  • Adversarial Robustness in Machine Learning
  • Acoustic Wave Phenomena Research
  • Optimization and Search Problems
  • Robotic Path Planning Algorithms
  • Reinforcement Learning in Robotics
  • Advanced Optimization Algorithms Research
  • Generative Adversarial Networks and Image Synthesis
  • Digital Media Forensic Detection
  • Advanced Adaptive Filtering Techniques
  • Fluid Dynamics Simulations and Interactions

University of Tsukuba
2009-2024

RIKEN Center for Advanced Intelligence Project
2019-2024

Shinshu University
2013-2021

Osaka University
2021

Epson Information Technology College
2021

Seiko Holdings (Japan)
2021

Ōtani University
2014-2018

Nagano University
2014-2018

Institute of Engineering
2017

Inria Saclay - Île de France
2013

This paper presents topology optimization for thermal cloaks expressed by level-set functions and explored using the covariance matrix adaptation evolution strategy (CMA-ES). Designed optimal configurations provide superior performances in steady-state conduction succeed realizing invisibility, despite structures being simply composed of iron aluminum without inhomogeneities caused employing metamaterials. To design cloaks, a prescribed objective function is used to evaluate difference...

10.1063/1.5016090 article EN Applied Physics Letters 2018-02-05

We generate optimal topologies in the structural design of bifunctional cloaks manipulating heat flux and direct current, using topology optimization that incorporates both thermal conductivity electrical current. The cloak composed bulk isotropic materials is designed to restrain disturbances caused by an insulated obstacle minimizing difference between cloaked distributions referenced when no present. Our results show presented optimizations provide reproduce undisturbed temperature...

10.1063/1.5123908 article EN Applied Physics Letters 2019-10-21

10.1016/j.ijheatmasstransfer.2020.120082 article EN International Journal of Heat and Mass Transfer 2020-07-09

We introduce an acceleration for covariance matrix adaptation evolution strategies (CMA-ES) by means of adaptive diagonal decoding (dd-CMA). This endows the default CMA-ES with advantages separable without inheriting its drawbacks. Technically, we a [Formula: see text] that expresses coordinate-wise variances sampling distribution in DCD form. The can learn rescaling problem coordinates within linear number function evaluations. Diagonal also exploit separability problem, but, crucially,...

10.1162/evco_a_00260 article EN Evolutionary Computation 2019-05-23

By including acoustic-elastic interactions in a topology optimization based on the covariance matrix adaptation evolution strategy, we developed acoustic cloaks of optimal design that render an object unobservable through airborne and water-borne sounds. This strategy helps exploring topologies minimize scattering sounds around made from acrylonitrile butadiene styrene copolymers frequently used as ink 3D printers. applying level set methods, our designed are expressed iso-surfaces...

10.1063/5.0040911 article EN Applied Physics Letters 2021-03-08

Various strategies have been proposed to achieve invisibility cloaking, but usually only one phenomenon is controlled by each device. Cloaking an object from two different waves, such as electromagnetic and acoustic a challenging problem, if not impossible, be achieved using transformation theory metamaterials, which are the major approaches in physics. Here, developing topology optimization for controlling both we present multidisciplinary attempt designing biphysical cloaks with...

10.1364/oe.450787 article EN cc-by Optics Express 2022-01-28

Many multiobjective evolutionary algorithms rely on the nondominated sorting procedure to determine relative quality of individuals with respect population. In this paper, we propose a new method decrease cost procedure. Our approach is at start algorithm run and update knowledge as population changes. order do efficiently, special data structure called M-front, hold part The M-front uses geometric algebraic properties Pareto dominance relation convert orthogonal range queries into interval...

10.1109/tevc.2014.2366498 article EN IEEE Transactions on Evolutionary Computation 2014-10-31

We propose a novel natural gradient based stochastic search algorithm, VD-CMA, for the optimization of high dimensional numerical functions. The algorithm is comparison-based and hence invariant to monotonic transformations objective function. It adapts multivariate normal distribution with restricted covariance matrix twice dimension as degrees freedom, representing an arbitrarily oriented long axis additional axis-parallel scaling. derive different components show linear internal time...

10.1145/2576768.2598258 preprint EN 2014-07-11

Safety alignment is an essential research topic for real-world AI applications. Despite the multifaceted nature of safety and trustworthiness in AI, current methods often focus on a comprehensive notion safety. By carefully assessing models from existing safety-alignment methods, we found that, while they generally improved overall performance, failed to ensure specific categories. Our study first identified difficulty eliminating such vulnerabilities without sacrificing model's helpfulness....

10.48550/arxiv.2502.02153 preprint EN arXiv (Cornell University) 2025-02-04

We propose a novel variant of the covariance matrix adaptation evolution strategy (CMA-ES) using parameterized with smaller number parameters. The motivation restricted is twofold. First, it requires less internal time and space complexity that desired when optimizing function on high dimensional search space. Second, evaluations to adapt if rich enough express variable dependencies problem. In this paper we derive computationally efficient way update where model richness controlled by an...

10.1145/2908812.2908863 preprint EN Proceedings of the Genetic and Evolutionary Computation Conference 2016-07-20

Hyperparameter optimization (HPO), formulated as black-box (BBO), is recognized essential for automation and high performance of machine learning approaches. The CMA-ES a promising BBO approach with degree parallelism, has been applied to HPO tasks, often under parallel implementation, shown superior other approaches including Bayesian (BO). However, if the budget hyperparameter evaluations severely limited, which case end users who do not deserve computing, exhausts without improving due...

10.1609/aaai.v35i10.17109 article EN Proceedings of the AAAI Conference on Artificial Intelligence 2021-05-18

We propose an approach to saddle point optimization relying only on oracles that solve minimization problems approximately. analyze its convergence property a strongly convex–concave problem and show linear toward the global min–max point. Based analysis, we develop heuristic adapt learning rate. An implementation of developed using (1+1)-CMA-ES as oracle, namely, Adversarial-CMA-ES, is shown outperform several existing approaches test problems. Numerical evaluation confirms tightness...

10.1145/3510425 article EN ACM Transactions on Evolutionary Learning and Optimization 2022-02-02
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