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A machine learning framework for acoustic reflector mapping

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arXiv

arXiv 2024年

作者： Saqib, Usama Marchegiani, Letizia Jensen, Jesper Rindom Department of Engineering and Architecture University of Parma Italy Audio Analysis Lab Department of Electrical Systems Aalborg University Denmark

Sonar-based indoor mapping systems have been widely employed in robotics for several decades. While such systems are still the mainstream in underwater and pipe inspection settings, the vulnerability to noise reduced, over time, their general widespread usage in favour of other modalities(e.g., cameras, lidars), whose technologies were encountering, instead, extraordinary advancements. Nevertheless, mapping physical environments using acoustic signals and echolocation can bring significant benefits to robot navigation in adverse scenarios, thanks to their complementary characteristics compared to other sensors. Cameras and lidars, indeed, struggle in harsh weather conditions, when dealing with lack of illumination, or with non-reflective walls. Yet, for acoustic sensors to be able to generate accurate maps, noise has to be properly and effectively handled. Traditional signal processing techniques are not always a solution in those cases. In this paper, we propose a framework where machine learning is exploited to aid more traditional signal processing methods to cope with background noise, by removing outliers and artefacts from the generated maps using acoustic sensors. Our goal is to demonstrate that the performance of traditional echolocation mapping techniques can be greatly enhanced, even in particularly noisy conditions, facilitating the employment of acoustic sensors in state-of-the-art multi-modal robot navigation systems. Our simulated evaluation demonstrates that the system can reliably operate at an SNR of −10dB. Moreover, we also show that the proposed method is capable of operating in different reverberate environments. In this paper, we also use the proposed method to map the outline of a simulated room using a robotic platform. © 2024, CC BY.

关键词： Multipurpose robots

Explainable AI and Law: An Evidential Survey

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Digital Society 2023年第1期3卷 1-33页

作者： Richmond, Karen McGregor Muddamsetty, Satya M. Gammeltoft-Hansen, Thomas Olsen, Henrik Palmer Moeslund, Thomas B. Faculty of Law Copenhagen University Copenhagen Denmark Department of Architecture Design and Media Technology (CREATE) Visual Analysis and Perception Lab Aalborg University Aalborg Denmark

Decisions made by legal adjudicators and administrative decision-makers often found upon a reservoir of stored experiences, from which is drawn a tacit body of expert knowledge. Such expertise may be implicit and opaque, even to the decision-makers themselves, and generates obstacles when implementing AI for automated decision-making tasks within the legal field, since, to the extent that AI-powered decision-making tools must found upon a stock of domain expertise, opacities may proliferate. This raises particular issues within the legal domain, which requires a high level of accountability, thus transparency. This requires enhanced explainability, which entails that a heterogeneous body of stakeholders understand the mechanism underlying the algorithm to the extent that an explanation can be furnished. However, the “black-box” nature of some AI variants, such as deep learning, remains unresolved, and many machine decisions therefore remain poorly understood. This survey paper, based upon a unique interdisciplinary collaboration between legal and AI experts, provides a review of the explainability spectrum, as informed by a systematic survey of relevant research papers, and categorises the results. The article establishes a novel taxonomy, linking the differing forms of legal inference at play within particular legal sub-domains to specific forms of algorithmic decision-making. The diverse categories demonstrate different dimensions in explainable AI (XAI) research. Thus, the survey departs from the preceding monolithic approach to legal reasoning and decision-making by incorporating heterogeneity in legal logics: a feature which requires elaboration, and should be accounted for when designing AI-driven decision-making systems for the legal field. It is thereby hoped that administrative decision-makers, court adjudicators, researchers, and practitioners can gain unique insights into explainability, and utilise the survey as the basis for further research within the

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Time Domain analysis for Motions of Ships With the Effects of Steady Flow Using a Rankine Panel Method

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Journal of Offshore Mechanics and Arctic Engineering 2025年第4期147卷 041203页

作者： Zhou, Bo Wu, Zhifei Wang, Yu Han, Xiaoshuang Zhang, Teng Zhang, Guiyong State Key Lab of Structural Analysis Optimization and CAE Software for Industrial Equipment School of Naval Architecture Engineering Dalian University of Technology Dalian 116024 China Marine Engineering College Dalian Maritime University Dalian 116026 China

A novel numerical approach, leveraging the 3D time domain Rankine panel method, has been introduced to simulate ship motions while accounting for the effects of ship wave. This method treats ship wave as steady flow, enabling a more accurate representation of physical phenomena. The underlying numerical formulation used to solve the ship wave potential is comprehensively derived, establishing the unsteady disturbance potential's boundary value problem and incorporating the effects of steady motion. Wave forces and motion responses of various ship forms were computed and compared with experimental data and results from other numerical techniques. The findings reveal that calculations based on uniform stream exhibit significantly larger errors than those considering double body flow or ship wave. For the Wigley I and S175 models, the discrepancies between double body flow and ship wave predictions are relatively minor, with ship wave calculations demonstrating slightly higher accuracy. In contrast, for the intricate KRISO Container Ship (KCS) model, where ship wave is more pronounced, the error margin for ship wave calculations relative to experimental results remains within 21.9%, while errors for double body flow calculations can reach up to 50.2%. This highlights the superior accuracy of ship wave-based calculations for the KCS model. Overall, the proposed method effectively captures the influence of steady flow and demonstrates significant advantages in computing pronounced ship wave generated during realistic ship motion.

关键词： Ships ship motion Rankine panel method Waves Flow (Dynamics) hydrodynamics wave mechanics and wave effects computational fluid dynamics ship wave Boundary-value problems steady flow

Variable stiffness design optimization of fiber-reinforced composite laminates with regular and irregular holes considering fiber continuity for additive manufacturing

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Chinese Journal of Aeronautics 2025年第3期38卷 334-354页

作者： Yi LIU Zunyi DUAN Chunping ZHOU Yuan SI Chenxi GUAN Yi XIONG Bin XU Jun YAN Jihong ZHU School of Mechanics Civil Engineering&ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China Key Lab for Airborne Hi-performance Electro-magnetic Window RISACJinan 130012China School of System Design and Intelligent Manufacturing Southern University of Science and TechnologyShenzhen 518055China State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian 116024China State IJR Center of Aerospace Design and Additive Manufacturing MIIT Lab of Metal Additive Manufacturing and Innovative DesignNorthwestern Polytechnical UniversityXi’an 710072China

Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design optimization of variable stiffness of fiber-reinforced composite laminates has attracted widespread attention from scholars and industry. In these aerospace composite structures, numerous cutout panels and shells serve as access points for maintaining electrical, fuel, and hydraulic systems. The traditional fiber-reinforced composite laminate subtractive drilling manufacturing inevitably faces the problems of interlayer delamination, fiber fracture, and burr of the laminate. Continuous fiber additive manufacturing technology offers the potential for integrated design optimization and manufacturing with high structural performance. Considering the integration of design and manufacturability in continuous fiber additive manufacturing, the paper proposes linear and nonlinear filtering strategies based on the Normal Distribution Fiber Optimization (NDFO) material interpolation scheme to overcome the challenge of discrete fiber optimization results, which are difficult to apply directly to continuous fiber additive manufacturing. With minimizing structural compliance as the objective function, the proposed approach provides a strategy to achieve continuity of discrete fiber paths in the variable stiffness design optimization of composite laminates with regular and irregular holes. In the variable stiffness design optimization model, the number of candidate fiber laying angles in the NDFO material interpolation scheme is considered as design variable. The sensitivity information of structural compliance with respect to the number of candidate fiber laying angles is obtained using the analytical sensitivity analysis method. Based on the proposed variable stiffness design optimization method for complex perforated composite laminates, the numerical examples cons

关键词： Variable stiffness composite laminates Discrete material interpolation scheme Normal distribution fiber optimization Discrete fiber continuous filtering strategy Additive manufacturing of composite laminates

An Improved Functional Link architecture for Nonlinear AEC

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An Improved Functional Link Architecture for Nonlinear AEC

European Signal Processing Conference (EUSIPCO)

作者： Srikanth Burra Asutosh Kar Mads Græsbøll Christensen Indian Institute of Information Technology Design and Manufacturing Chennai India Department of Architecture Design and Media Technology Audio Analysis Lab Aalborg University Denmark

ISBN: (数字)9789082797091

ISBN: (纸本)9781665467995

In practice, hands-free devices commonly employ low-cost electronic components. Unfortunately, the nonlinear distortion arising from them affects the performance of acoustic echo cancellers. To address this issue, this paper proposes a new adaptive filtering algorithm based on nonlinear acoustic echo cancellation (NAEC) framework for improving its echo cancellation performance. The advanced method employs a novel combination of an adaptive filter based on sub-filter and proportionate adaptation, and presents an enhanced NAEC framework. In addition to that, both convergence and steady-state analysis of the proposed NAEC algorithm are presented. The performance evaluation made in the presence of speech and colored noise inputs has shown an average improvement of 3–4 dB compared to the existing algorithms.

关键词： Performance evaluation Echo cancellers Filtering Nonlinear distortion Signal processing algorithms Adaptive filters Nonlinear filters

Study on Vortex-Induced Vibration Characteristics of Small Mass Ratio Free-Rotating Fairing Structure

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SSRN 2023年

作者： Xu, Haoyuan Dai, Changming Zhou, Bo Wang, Jie Han, Xiaoshuang Zhang, Guiyong State Key Lab of Structural Analysis Optimization CAE Software for Industrial Equipment School of Naval Architecture Engineering Dalian University of Technology Dalian116024 China Marine Engineering College Dalian Maritime University Dalian116026 China

The small mass ratio rigidly cylinder is the most widely studied model of vortex-induced vibration, this paper loads a user-defined program (UDF) in the commercial software Fluent to implement the Newmark-β method for solving the structural vibration equation and rotation equation. This paper simulates the classical cylindrical vortex-induced vibration experiments with the mass ratio of 2.6 and the free-rotating fairing with small mass ratio, and discusses the vibration reduction mechanism and vibration reduction characteristics of the free-rotating fairing in terms of amplitude, frequency, motion trajectory and vortex shedding mode, etc. The results show that the two-dimensional mesh can capture the complete vortex-induced vibration branches;the free-rotating fairing changes the vibration characteristics of the original cylinder and has superior vibration reduction performance;fairing rotation affects the development and shedding of the vortex. At last, this paper develops a structural vibration characteristic analysis thought that is dominated by the vortex shedding mode. © 2023, The Authors. All rights reserved.

关键词： Vortex flow

A 3d Tebem Forsimulating Time Domain Motions of Ships in Waves with Forward Speed Considering the Effects of Ship Wave

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SSRN 2024年

作者： Wu, Zhifei Zhou, Bo Wang, Yu Jin, Guangqiu Liu, Hui Zhang, Teng State Key Lab of Structural Analysis Optimization and CAE Software for Industrial Equipment School of Naval Architecture Engineering Dalian University of Technology Dalian116024 China Centre for Eco-Environment Modelling State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing China

A newly developed numerical method based on TEBEM is employed to solve the time domain motions for ships sailing in waves with forward speed. The ship wave potential’s boundary value problem is derived, and a numerical method based on TEBEM is established to directly solve the ship wave potential and its spatial derivatives. Comprehensive derivations are conducted for the boundary value problem of unsteady disturbance potential with the influence of ship wave. By retaining cross-coupling terms between steady and unsteady flows, the effects of steady terms related to speed effect are fully considered. A TEBEM capable of efficiently and accurately solving unsteady disturbance potential and its spatial derivatives is established. Numerical results show that the present method yields wave making resistance that exhibit closer agreement with experimental data. In time domain simulations, it’s found that ship motion responses and hydrodynamic forces calculated using the present method that are closer to experimental data. This is particularly evident for KCS, which produces significant ship wave. This indicates that the numerical method exhibits high prediction accuracy and numerical stability for different ships, demonstrating robustness, and has significant advantages in dealing with practical ships featuring intricate structures, making it valuable for practical engineering applications. © 2024, The Authors. All rights reserved.

关键词： Numerical methods

The Wake Evolution Mechanisms of The(Mau)Propeller Operating in Oblique Flow

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SSRN 2023年

作者： Zhou, Bo Yu, Jiawei Dai, Changming Zhang, Binbin Han, Xiaoshuang Zhang, Guiyong State Key Lab of Structural Analysis Optimization and CAE Software for Industrial Equipment School of Naval Architecture Engineering Dalian University of Technology Dalian Province 116024 China Marine Engineering College Dalian Maritime University Dalian Province 116026 China

In this paper, the wake field of MAU type propeller is numerically simulated by large eddy simulation (LES), and the wake behavior of propeller under the condition of axial symmetry and three different inclination angles is compared systematically. The complex vortex system in the wake field is quantitatively analyzed. The cause of the trailing vortex system changing from stable state to unstable state is discussed, and the potential mechanism of wake evolution and instability is explored. The key vortex structure related to the unsteady process of propeller wake is solved, and the relationship between the interaction of tip vortex and the evolution of unstable states is extended, and the important reasons for the instability of tip vortex are clarified. The results show that the decrease of tip vortex distance, the interaction between tip vortex and sheet vortex, and the intensity of vortex are correlated with tip vortex instability. The relationship between hub vortex and the sudden instability mechanism of wake field and the contribution of the secondary vortex to the instability mechanism are studied in this work, and the related research of rotor wake instability is supplemented, which has important practical significance for the design and optimization of propeller. © 2023, The Authors. All rights reserved.

关键词： Vortex flow

Scouring Development and Self-Burial of a Subsea Pipeline Attached with Porous/Flexible Spoilers

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SSRN 2023年

作者： Zhou, Bo Wang, Jie Cui, Xiaohui Hu, Chaodong Liu, Hui Wang, Xikun State Key Lab of Structural Analysis Optimization and CAE Software for Industrial Equipment School of Naval Architecture Engineering Dalian University of Technology Dalian Province 116024 China Research Center of Fluid Machinery Engineering and Technology Jiangsu University Zhenjiang212013 China

Free spanning of subsea pipelines caused by local scour is a primary concern during its operation. This study aims to propose an effective method to protect the pipeline form spanning. The experiments were conducted in clear-water scour conditions. Impermeable spoiler, porous spoiler and flexible spoiler were considered for both fixed and self-burial test. The flow fields around the pipeline were obtained using the particle image velocimetry (PIV) technique. The scour of a fixed subsea pipeline indicates the spoiler can accelerates the erosion rate significantly. When the pipeline leaves the seabed, the scour profile is featured by two scour pits and two sand dunes. The scour process of flexible spoilers includes two stages: quasi-steady and flapping and the flapping downward motion is the main cause for sediment burst. The shelter effect of flexible spoiler protects the pipeline form vigorous scouring and achieves a 10% decrease of the maximum scour depth. The trapped vortex and disturbance propagation caused by the orifice jet flow inhibits the scour process to some extent for porous spoiler. However, the self-burial results indicate the porous spoiler can accelerates the self-burial process up to 5.5 times compared to smooth pipeline and shows a better performance than impermeable spoiler. © 2023, The Authors. All rights reserved.

关键词： Scour