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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

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Inline Photometrically Calibrated Hybrid Visual SLAM

Inline Photometrically Calibrated Hybrid Visual SLAM

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IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Nicolas Abboud Malak Sayour Imad H. Elhajj John Zelek Daniel Asmar Vision and Robotics Lab Maroun Semaan Faculty of Engineering and Architecture American University of Beirut Beirut Lebanon Department of System Design Engineering University of Waterloo Waterloo Canada

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

This paper presents an integrated approach to Visual SLAM, merging online sequential photometric calibration within a Hybrid direct-indirect visual SLAM (H-SLAM). Photometric calibration helps normalize pixel intensity values under different lighting conditions, and thereby improves the direct component of our H-SLAM. A tangential benefit also results to the indirect component of H-SLAM given that the detected features are more stable across variable lighting conditions. Our proposed photometrically calibrated H-SLAM is tested on several datasets, including the TUM monoVO as well as on a dataset we created. Calibrated H-SLAM outperforms other state of the art direct, indirect, and hybrid Visual SLAM systems in all the experiments. Furthermore, in online SLAM tested at our site, it also significantly outperformed the other SLAM systems.

关键词： Visualization Simultaneous localization and mapping Measurement units Merging Lighting Inertial navigation Feature extraction Calibration Intelligent robots

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MGSO: Monocular Real-time Photometric SLAM with Efficient 3D Gaussian Splatting

arXiv

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arXiv 2024年

作者： Hu, Yan Song Abboud, Nicolas Ali, Muhammad Qasim Yang, Adam Srebrnjak Elhajj, Imad Asmar, Daniel Chen, Yuhao Zelek, John S. Vision and Image Processing Lab The Faculty of System Design Engineering The University of Waterloo 200 University Avenue West WaterlooON Canada Vision and Robotics Lab Maroun Semaan Faculty of Engineering and Architecture American University of Beirut Riad El Solh Beirut1107 2020 Lebanon

Real-time SLAM with dense 3D mapping is computationally challenging, especially on resource-limited devices. The recent development of 3D Gaussian Splatting (3DGS) offers a promising approach for real-time dense 3D reconstruction. However, existing 3DGS-based SLAM systems struggle to balance hardware simplicity, speed, and map quality. Most systems excel in one or two of the aforementioned aspects but rarely achieve all. A key issue is the difficulty of initializing 3D Gaussians while concurrently conducting SLAM. To address these challenges, we present Monocular GSO (MGSO), a novel real-time SLAM system that integrates photometric SLAM with 3DGS. Photometric SLAM provides dense structured point clouds for 3DGS initialization, accelerating optimization and producing more efficient maps with fewer Gaussians. As a result, experiments show that our system generates reconstructions with a balance of quality, memory efficiency, and speed that outperforms the state-of-the-art. Furthermore, our system achieves all results using RGB inputs. We evaluate the Replica, TUM-RGBD, and EuRoC datasets against current live dense reconstruction systems. Not only do we surpass contemporary systems, but experiments also show that we maintain our performance on laptop hardware, making it a practical solution for robotics, A/R, and other real-time applications. © 2024, CC BY-NC-SA.

关键词： SLAM robotics

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Inline Photometrically Calibrated Hybrid Visual SLAM

arXiv

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arXiv 2024年

作者： Abboud, Nicolas Sayour, Malak Elhajj, Imad H. Zelek, John Asmar, Daniel Vision and Robotics Lab Maroun Semaan Faculty of Engineering and Architecture American University of Beirut Riad El Solh Beirut1107 2020 Lebanon Department of System Design Engineering University of Waterloo 200 University Avenue West WaterlooON Canada

关键词： Lighting

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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 338-358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 University Research & Development Institute of Northwestern Polytechnical University in Shenzhen Key Lab for Airborne Hi-performance Electro-magnetic Window RISAC School of System Design and Intelligent Manufacturing Southern University of Science and Technology State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of Technology State IJR Center of Aerospace Design and Additive Manufacturing MIIT Lab of Metal Additive Manufacturing and Innovative DesignNorthwestern Polytechnical University

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 consid

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Automated simulation for household road traffic noise exposure: Application and field evaluation in a high-density city

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Computers, Environment and Urban systems 2023年第1期104卷

作者： Guo, Mengdi Ni, Michael Y. Shyu, Rong-Juin Ji, John S. Huang, Jianxiang Department of Architecture School of Architecture Tianjin University Tianjin China Department of Urban Planning and Design the University of Hong Kong Hong Kong Special Administrative Region China The University of Hong Kong Shenzhen Institute of Research and Innovation 5/F Key Laboratory Platform Building Shenzhen Virtual University Park No.6 Yuexing 2nd Rd Nanshan Shenzhen518057 China School of Public Health LKS Faculty of Medicine The University of Hong Kong Hong Kong Special Administrative Region China The State Key Laboratory of Brain and Cognitive Sciences The University of Hong Kong Hong Kong Special Administrative Region China Urban Systems Institute the University of Hong Kong Hong Kong Special Administrative Region Hong Kong Department of System Engineering and Naval Architecture National Taiwan Ocean University Keelung Taiwan Vanke School of Public Health Tsinghua University Beijing China Sustainable High Density Cities Lab HKUrban Lab Faculty of Architecture the University of Hong Kong Hong Kong Special Administrative Region Hong Kong

Road traffic noise is a major nuisance and a risk factor of poor health for urban dwellers. A household's exposure to road traffic noise, especially in a high-density city, can be easily modified by the surrounding built environment, i.e., roads, traffic, buildings, and the topography. This leads to high variation in noise exposure between neighboring households. Existing simulation-based studies were limited in accounting for the variation of noise exposure at the household level, which restricted their applications in public health research involving large numbers of participants. This paper describes a novel simulation-based workflow to assess household traffic noise exposure, which consists of 1) a source model to assess road traffic noise levels, 2) a propagation model to simulate noise propagation in complex three-dimensional urban areas, 3) an automation algorithm to process large quantity of simulation runs and data. The workflow has been evaluated using field studies conducted in Sham Shui Po District, Hong Kong, with reasonably good agreements between simulated and measured data. It was then used to assess road traffic noise exposure for a sample of 6158 households enrolled in the FAMILY Cohort, representing Hong Kong's population dwelling in the dense urban areas. Results showed that 83% of sampled households have been exposed to excessive road traffic noise above the World Health Organization (WHO) standard, or 30% above the local standard. The estimated burden of disease is over 45,000 disability-adjusted life-years (DALYs) from both high annoyance and sleep disturbance for households in Hong Kong. The study has contributed to the methodologies and datasets in evaluating noise exposure in high-density cities, which can further support urban noise mitigation policies and planning and population-based health studies in the next steps. © 2023 Elsevier Ltd

关键词： Three dimensional computer graphics

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Actions against the double burden of malnutrition in Peru: a community-informed system dynamics model

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The Lancet Regional Health - Americas 2025年 46卷 101102-101102页

作者： Seferidi, Paraskevi Guzman-Abello, Laura Ballard, Ellis Creed-Kanashiro, Hilary M. Huicho, Luis Miranda, J Jaime Millett, Christopher Bernabe-Ortiz, Antonio Public Health Policy Evaluation Unit School of Public Health Imperial College London London United Kingdom Department of Design School of Architecture and Design Universidad de los Andes Bogota Colombia Social System Design Lab Brown School at Washington University in St. Louis St. Louis United States Instituto de Investigación Nutricional Lima Peru Centro de Investigación en Salud Materna e Infantil Centro de Investigación para el Desarrollo Integral y Sostenible and Facultad de Medicina Universidad Peruana Cayetano Heredia Lima Peru CRONICAS Centre of Excellence in Chronic Diseases Universidad Peruana Cayetano Heredia Lima Peru Sydney School of Public Health Faculty of Medicine and Health University of Sydney Sydney Australia NOVA National School of Public Health Public Health Research Centre Comprehensive Health Research Center NOVA University Lisbon Lisbon Portugal

Background: Peru's progress in reducing stunting has stagnated since 2018, while the country is facing increasing levels of overnutrition, leading to a double burden of malnutrition. However, this shift in nutrition burden is not reflected in Peru's nutrition policy agenda. This study aims to identify leverage points for actions against population-level double burden of malnutrition in Peru. Methods: We developed a system dynamics model that simulates changes in overweight and stunting over time in Peru through changes in food system drivers. The model was conceptually informed by policymakers, practitioners and community members in Peru and used quantitative and qualitative data from secondary sources and published literature. Findings: The model indicated that several overnutrition policies, including policies targeting food availability and affordability, may decelerate but not halt the increase of overweight in the country, mainly due to industry resistance. However, in the long term, the reallocation of resources towards overnutrition policies may inadvertently hinder progress towards stunting targets. Transforming nutrition policy governance, from siloed overnutrition and undernutrition policies towards a common policy framework against the double burden of malnutrition was the only modelled scenario that halted the rise in overnutrition, while keeping Peru on course to reach its stunting goals. Interpretation: Transition away from policy landscapes that focus on single nutrition outcomes towards synergistic actions that target malnutrition in all forms is a long-term solution towards achieving global nutrition goals. Such policy transitions are especially important in low and middle-income countries like Peru, which are affected by the double burden of malnutrition. Funding: This study was supported by a research grant from the Biotechnology and Biological Sciences Research Council (BBSRC) (grant reference: BB/T009004/1). © 2025 The Authors

关键词： Double burden of malnutrition Double-duty actions Peru system dynamics

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Mapping food system drivers of the double burden of malnutrition using community-based system dynamics: a case study in Peru

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BMC global and public health 2024年第1期2卷 15页

作者： Carmen Quinteros-Reyes Paraskevi Seferidi Laura Guzman-Abello Christopher Millett Antonio Bernabé-Ortiz Ellis Ballard CRONICAS Center of Excellence in Chronic Diseases Universidad Peruana Cayetano Heredia Lima Peru. Public Health Policy Evaluation Unit School of Public Health Imperial College London London UK. paraskevi.seferidi14@imperial.ac.uk. Department of Design School of Architecture and Design Universidad de los Andes Bogota Colombia. Public Health Policy Evaluation Unit School of Public Health Imperial College London London UK. Comprehensive Health Research Center (CHRC) and Public Health Research Centre National School of Public Health NOVA University Lisbon Portugal. Social System Design Lab Brown School at Washington University in St. Louis St. Louis USA.

BACKGROUND:Peru is facing a double burden of malnutrition (DBM), characterized by the co-existence of undernutrition and overnutrition. Double-duty actions that concurrently target common drivers of undernutrition and overnutrition, while ensuring no unintended side effects, are recommended to effectively address the DBM. To understand these complex common mechanisms and design context-specific double-duty actions, there is a need for participatory systems approaches. This paper provides a case study of applying a community-based system dynamics approach to capture stakeholder perspectives of food system drivers of the DBM in two regions in Peru. METHODS:We implemented a multi-stage community-based system dynamics approach, which included processes for research capacity building for systems approaches, and the designing, piloting, and implementation of stakeholder workshops. A total of 36 stakeholders, representing diverse perspectives, participated in five group model building workshops. Stakeholder views are presented in a causal loop diagram that showcases the feedback mechanisms between key food system drivers of overweight and stunting in Peru. RESULTS:The causal loop diagram highlights that prioritization of undernutrition over overnutrition in the policymaking process, due to Peru's historically high levels of undernutrition, may undermine action against the DBM. It also describes potential mechanisms of unintended impacts of undernutrition policies on the DBM in Peru, including impacts related to within-family distribution and quality of food provided through food assistance programs, and unintended impacts due to regional dynamics. CONCLUSIONS:This paper highlights the importance of a participatory approach to understand local needs and priorities when recommending double-duty actions in Peru and shares practical methodological guidance on applying participatory systems approaches in public health.

关键词： Community-based system dynamics Double burden of malnutrition Double-duty actions Food system Group model building Peru

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Memory fast-forward: A low cost special function unit to enhance energy efficiency in GPU for big data processing 15

Memory fast-forward: A low cost special function unit to enh...

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design, Automation and Test in Europe Conference and Exhibition

作者： Eunhyeok Park Junwhan Ahn Sungpack Hong Sungjoo Yoo Sunggu Lee Embedded System Architecture Lab POSTECH Design Automation Lab Seoul National University Oracle Labs

ISBN: (纸本)9783981537048

Big data processing, e.g., graph computation and MapReduce, is characterized by massive parallelism in computation and a large amount of fine-grained random memory accesses often with structural localities due to graph-like data dependency. Recently, GPU is gaining more and more attention for servers due to its capability of parallel computation. However, the current GPU architecture is not well suited to big data workloads due to the limited capability of handling a large number of memory requests. In this paper, we present a special function unit, called memory fast-forward (MFF) unit, to address this problem. Our proposed MFF unit provides two key functions. First, it supports pointer chasing which enables computation threads to issue as many memory requests as possible to increase the potential of coalescing memory requests. Second, it coalesces memory requests bound for the same cache block, often due to structural locality, thereby reducing memory traffics. Both pointer chasing and memory request coalescing contribute to reducing memory stall time as well as improving the real utilization of memory bandwidth, by removing duplicate memory traffics, thereby improving performance and energy efficiency. Our experiments with graph computation algorithms and real graphs show that the proposed MFF unit can improve the energy efficiency of GPU in graph computation by average 54.6% at a negligible area cost.

关键词： Graphics processing units Instruction sets Registers Memory management Arrays Big data

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Vibration-modal analysis model for multi-span pipeline with different support conditions

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Computer Modelling and New Technologies 2014年第5期18卷 7-13页

作者： Liu, Jun He, Xing Liu, Qingyou Naibin, Jiang Chen, Huang School of Civil Engineering and Architecture Southwest Petroleum University Chengdu China Modern Design and Simulation Lab for Oil and Gas Equipment's Southwest Petroleum University Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

Vibration characteristics analysis is important in the design of multi-span pipeline with different support conditions. In order to analyze the natural frequency and the vibration modal of the multi-span pipeline, a matrix transfer method is proposed in this paper. With the multi-span pipeline divided into single-span pipes, the transmission formulas for the deflection, angle, bending and shear between two adjacent spans are deduced, in combination with the Krylov function solution of the free vibration equation for the single-span pipe, and the constraint condition between the two adjacent spans of the multi-span pipeline. According to the boundary conditions on the starting and ending spans, the natural frequency equation and the vibration modal function between two adjacent spans of the multi-span pipeline are presented. The FORTRAN program based on the above principle is written, and the natural vibration frequencies and the vibration modals of two typical multi-span pipelines are investigated and compared with the results from ABAQUS. It is shown that the model presented in this paper is efficient in the analysis of multi-span pipeline and has the advantages of high computational efficiency and convenience for engineering practice application.

关键词： Natural frequencies

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