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Fine grains with high-density annealing twins and precipitates inducing favorable strength and excellent plasticity in laser powder b e d fusion-fabricate d Inconel 718 via deep cryogenic and heat treatments

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Journal of Materials Science & technology 2024年第20期187卷 28-48页

作者： Bo Liu Jiayu Xu Yubi Gao Yong Hu Xiaokang Yang Yutian Ding Dong Zhang Sujun Lu State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050China School of Material Science and Engineering Lanzhou University of TechnologyLanzhou 730050China School of Electromechanics and Automobile Engineering Tianshui Normal UniversityTianshui 741001China Jinchuan Nickel Cobalt Research and Design Institute Jinchuan Group Co.LtdJinchang 737100China

Tailoring high-density annealing twins in laser powder bed fusion(LPBF)-fabricated alloys based on their intrinsic residual stress requires high annealing temperatures and/or long-term annealing,result-ing in the abnormal growth of large recrystallized grains,which is detrimental to mechanical *** work proposes a new strategy for achieving a favorable strength-plasticity synergy of the LPBF-fabricated Inconel 718 superalloy by performing a deep cryogenic treatment(DCT)with the subsequent heat treatment(including annealing and double aging)to tailor fine grains with“high-density annealing twins+precipitates”architectures and compares the obtained material with an alloy subjected to a direct heat treatment without a prior *** obtained results reveal that the additional internal stress gen-erated during DCT increases the stored energy and dislocation density,which provide a sufficient driving force for activating high-density annealing twin boundaries(63.2%)with fine grains(31.6μm)within a short annealing *** more homogeneous tailored microstructure with the“finer grains+high-density twins+precipitates”architectures decreases the mean free path of slipping dislocations,pro-moting intensive interactions with dislocations and inducing a strong strain hardening *** mul-tiple deformation modes of stacking faults coupled with Lomer-Cottrell locks,thin primary deformation twins,and secondary twins activated during tensile loading,sustaining a strong work hardening ability and delaying the plastic instability,which exhibits a high strength(yield strength of 1088 MPa and tensile strength of 1369 MPa)and excellent plasticity(elongation of 30%).This work not only describes a fea-sible method for simultaneously enhancing the strength and plasticity in additively manufactured(AM)alloys but also provides new insights into increasing the fraction of twins at a small grain size to improve the grain boundary-related properties without destroying the AM allo

关键词： Laser powder bed fusion Deep cryogenic treatment Stored energy High-density annealing twins Work hardening

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Scenario Generation for Strategic Decision-Making towards Net-Zero Aviation

Scenario Generation for Strategic Decision-Making towards Ne...

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AIAA Science and technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Almarzooqi, Ranya Chen, Haoyuan Bagdatli, Burak Pfaender, Holger Mavris, Dimitri Aerospace Systems Design Laboratory Georgia Institute of Technology School of Aerospace Engineering AtlantaGA30332 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Being a major contributor to both global economics and global greenhouse gas emissions, the aviation industry is experiencing a great transition to a greener future. Recognizing the transition needs the collaborative efforts of all relevant industries, transcending the aviation sector alone. This is compounded by the pressing time constraint aimed at reducing emissions by 2050. All pose significant challenges to successfully identify the consequences of certain actions and their contribution towards the 2050 emission goals. In the context of multilateral decisions and their corresponding timing, this paper introduces a simulation model that captures the interconnected decision-making process of various stakeholders. This model is essential for effectively realizing the transition to a more sustainable aviation industry. The tool offers an innovative approach to simulate the decision-making process of stakeholders involved in the aviation industry, addressing the value and timing of their decisions. By utilizing this tool, stakeholders can explore and analyze decisions, enabling them to navigate the aviation industry’s transition to net-zero emissions. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Greenhouse gas emissions

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Scenario Modeling and Analysis for Strategic Decision-Making towards Net-Zero Aviation

Scenario Modeling and Analysis for Strategic Decision-Making...

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AIAA Science and technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Baali, Ilias Vinod, Yash Almarzooqi, Ranya Bagdatli, Burak Pfaender, Holger Mavris, Dimitri Aerospace Systems Design Laboratory Georgia Institute of Technology School of Aerospace Engineering AtlantaGA30332 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

With the commercial aviation industry being a major contributor to global emissions, there is a growing sense of urgency among stakeholders to reduce carbon emissions generated by the industry. Industry stakeholders must collaborate and execute decisions at crucial moments in time and realize a scenario to achieve the goal of net-zero emissions by 2050. This work integrates a methodology for generating emissions-reducing scenarios for the aviation industry with an approach to simulate the fleet-level impacts for these scenarios and assess them in terms of pertinent metrics, such as CO2 emissions, airline operating costs, and flight ticket prices. The simulation approach is integrated into an environment called Sustainable Aviation Visualization Environment (SAVE) to allow users to compare the generated scenarios, analyze them, and aid aviation’s stakeholders in making informed decisions for enabling net-zero by 2050. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Sustainable Aviation Operating Costs Commercial Aviation Industry Electrification International Civil Aviation Organization Electric Aircraft Fuel Consumption Sustainable Aviation Fuel Alternative Fuels Available Seat Miles

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Graph-based Group Division Network for Referring Expression Comprehension

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IEEE Transactions on Circuits and Systems for Video technology 2025年第6期35卷 6170-6183页

作者： Ke, Jingcheng Wang, Jia Wong, Waikeung Toomey, Anne Wen, Jie Guangdong University of Technology School of Computer Science and Technology GuangZhou China Guangdong Pharmaceutical University College of Medical Information Engineering GDPU Guangdong Guangzhou China The Hong Kong Polytechnic University School of Fashion and Textiles Hong Kong Laboratory for Artificial Intelligence in Design Hong Kong Hong Kong The Royal College of Art Kensington Gore School of Design London South KensingtonSW7 2EU United Kingdom Harbin Institute of Technology School of Computer Science and Technology Shenzhen China

Referring expression comprehension (REC) aims at locating the target object described by an expression. We observe that most of the graph-based REC methods only focus on establishing relations between all objects in an image and the given expression during the graph construction while ignoring the relationships between objects in the same category. As a result, these methods are sub-optimal in locating the target object described by the expression, particularly when the target object is surrounded by objects of similar categories. Meanwhile, during reasoning, numerous irrelevant objects are considered for expression, which will introduce significant harmful noise. To address these issues, this paper proposes a new graph-based group division network (GBGDN). Different from the existing works, our work partitions the constructed graphs into several sub-graphs based on the categories of objects and expressions. In each sub-graph, the common visual features of objects will be strengthened through a feature enhancement strategy. Subsequently, the enhanced sub-graphs and expressions undergo joint processing via a filtering-based reasoning module designed to reduce the influence of unrelated nodes in each subgraph, facilitating more accurate reasoning and matching. Experimental results across various datasets, including RefCOCO /+/g, Flickr30K Entities, RefClef, and Ref-reasoning, showcase the superiority of our proposed method over existing approaches. Most importantly, our method does not need pre-training. © 1991-2012 IEEE.

关键词： Graph theory

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High Altitude Platform Systems (HAPS) Mission Planning for the Prediction of Potential Flight Delays for Commercial Aviation

High Altitude Platform Systems (HAPS) Mission Planning for t...

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AIAA Science and technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Cho, Kwangmin Berberian, Titien Poretti, Martin E. Balchanos, Michael Payan, Alexia P. Mavris, Dimitri N. Aerospace Systems Design Laboratory School of Aerospace Engineering Georgia Institute of Technology AtlantaGA30332 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

In recent years, weather events have been a major source of commercial aircraft flight delays, impacting the efficiency of airline operations. Furthermore, flight delays have become more significant for airlines due to climate change and challenging regulations on delay compensation. The current atmospheric data collection system relies primarily on traditional radiosondes sent twice a day at specific locations and at rather low altitudes. Therefore, there is an opportunity to improve data collection for severe weather phenomena impacting airline operations, especially at high altitudes. To address the need for atmospheric data collection, High-Altitude Platform Systems (HAPS) have been proposed due to their ability to collect data continuously across a broad region. Despite their potential to enhance the current data collection system, HAPS remains a relatively unstudied system with limited historical data available. To overcome this challenge, this research proposes a data-driven approach with ERA-5 reanalyzed high-altitude data used as a proxy for high-altitude atmospheric data collected by HAPS. This research aims to optimize a HAPS mission profile for accurate aircraft flight delay prediction by analyzing the correlations between high-altitude atmospheric data from HAPS missions, varying mission specifications, and flight delays. This data-driven simulation serves as a virtual testing ground for HAPS missions to understand how changes in mission attributes affect the efficiency and usefulness of HAPS operations. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Radiosondes

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Study of Collaborative Space in Rebar Tying Robotic Systems

Study of Collaborative Space in Rebar Tying Robotic Systems

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2024 International Conference on Applied Mathematics, Modelling and Statistics Application, AMMSA 2024

作者： He, Jun Niu, Yuqian Qin, Ze Yin, Hao Yang, Xingyu School of Mechatronics Engineering Harbin Institute of Technology Harbin150000 China College of Design and Engineering National University of Singapore Singapore119077 Singapore School of Future Technology Harbin Institute of Technology Harbin150000 China

In the process of rebar tying operations conducted by multiple robots, the flexibility and operability of the robot's end effector directly influence the overall performance of the rebar tying system. This reflects the crucial role of the coordinated working capability of multiple robots in the trajectory planning of the rebar tying system. Utilizing an eight degrees of freedom rebar tying system composed of two collaborative robots and a truss structure, the D-H (Denavit-Hartenberg) dynamic model for each robotic arm is established. The working area of the system is ascertained via Monte Carlo methods. Flexibility and operability are adopted as metrics to evaluate the system's performance, subsequently leading to the formulation of a mathematical model for assessing the system's flexibility. MATLAB is employed to delineate the robotic working range and simulate analysis of flexibility and operability when operating on the rebar tying plane, yielding an intuitive distribution of system flexibility. By analysing the distribution of flexibility and operability across the working plane at varying robot spacing intervals, an optimal robot movement distance can be determined. This ensures that during operational tasks, the rebar tying system not only possesses a larger total working area but also maintains a high level of flexibility and operability within the collaborative region, thereby fulfilling the objective of enhancing workspace utilization and improving rebar tying efficiency. © Published under licence by IOP Publishing Ltd.

关键词： Degrees of freedom (mechanics)

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Trade Studies for Evaluating Lunar Surface Power Architectures

Trade Studies for Evaluating Lunar Surface Power Architectur...

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AIAA Science and technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Thakar, Bhargavi V. McNabb, Jeffrey T. Robertson, Bradford E. Mavris, Dimitri N. School of Aerospace Engineering Aerospace Systems Design Laboratory Georgia Institute of Technology AtlantaGA30308 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

It is necessary to have a flexible power architecture for the implementation of a sustainable lunar base at the lunar South Pole. Several power architectures alternatives consisting of several technology options have been proposed. However, there is a lack of a comprehensive trade analysis of comparative sizing for those options. This paper presents a comparative evaluation of surface and elevated solar panels for power generation, DC cables, AC cables, and power beaming for power distribution, and batteries and fuel cells for energy storage, which helps understand the configuration for power architectures that provide the most optimal solution with regards to landed mass. The comparison is done by using illumination profiles of specific lunar sites and evaluating that at differing heights above the ground. The method of combining time-dependent illumination data with static system sizing is detailed in the paper. The case study compares the different architectures that are possible using all combinations of the technologies that are discussed. This study evaluated each architecture across a wide range of customer power demands, transmission distances, and transmission voltages. Elevated solar panels and regenerative fuel cells were found to be the best option across all cases. The case study determined that there is no best-in-class power distribution system and that each one has portion of the design space in which they are most mass efficient. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Regenerative fuel cells

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design Environment for Lunar Operations and Systems Architecting

Design Environment for Lunar Operations and Systems Architec...

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AIAA Science and technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Boyer, Paul Park, Sean A. Jerresand, Cornelia Ramkumar, Siddharth Sambath Balchanos, Michael Pinon Fischer, Olivia J. Mavris, Dimitri N. Aerospace Systems Design Laboratory School of Aerospace Engineering Georgia Institute of Technology AtlantaGA30332 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

The interest in the space domain is on a steady rise since the last Apollo mission in 1972. This time, focus lies on the lunar South Pole and the establishment of a permanent lunar base for long-term human presence lead by NASAs Artemis missions. The new focus is a multi-level problem leveraging multiple stakeholders with collaborative/competitive interests and objectives. Developing a lunar base with city-level growth potential that exhibits complex interactions between assets and system processes requires the ability to rapidly explore, evaluate, prioritize, and select lunar architecture alternatives. To that end an architecting and sizing approach is proposed that enables the representation, modeling and simulation of a lunar base and its main components. Starting from the mission definition, a requirements flow-down process towards an executable modeling and simulation platform is adopted, following the R-F-L-P (Requirements-Functional-Logical-Physical) approach for defining the system architecting views. The outcome of this model-based exercise will result in a requirements-driven parametric interactive tradeoff environment, which will allow for exploration, prioritization, and selection of lunar architecture alternatives. The selection process is driven by tradeoff analysis and results which can address questions related to power demand and supply options, In-Situ Resource Utilization (ISRU) strategies, etc., and the broader aspect of technology selection of resource availability vs. mission-level risks. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： NASA

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Journal of Chemical Education Call for Papers: Special Issue on Teaching Innovation in Materials Science and engineering design

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JOURNAL OF CHEMICAL EDUCATION 2024年第12期101卷 5139-5141页

作者： Dong, Zhili Silva, Arlindo Lim, Teik-Cheng Ng, Leonard W. T. Goncalves, Rui A. School of Materials Science and Engineering Nanyang Technological University Singapore 639798 Singapore Engineering Product Development Pillar Singapore University of Technology and Design Singapore 487372 Singapore School of Science and Technology Singapore University of Social Sciences Singapore 599494 Singapore

The Journal of Chemical Education announces a call for papers for an upcoming special issue on Teaching Innovation in Materials Science and engineering design. This issue aims to highlight innovative approaches in teaching materials science and engineering, with a focus on integrating design principles, sustainability, and artificial intelligence into educational programs.

关键词： Materials Education designengineering Sustainability Artificial Intelligencein Education Innovative TeachingMethods Industry-Academia Collaboration

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A Process Evaluation and Visualization Framework for Unmanned Aerial System (UAS) Noise Certification Testing

A Process Evaluation and Visualization Framework for Unmanne...

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AIAA Science and technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Mali, Hajar Geneti, Nathnael F. Balchanos, Michael Harrison, Evan D. Mavris, Dimitri Aerospace Systems Design Laboratory School of Aerospace Engineering Georgia Institute of Technology AtlantaGA30332 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Expanding upon recent research into the effectiveness of noise testing processes for Unmanned Aerial Systems (UAS) [1], this study is seeking to develop methods for process analysis and efficiency assessment for a model-based framework to further optimize noise certification procedures. The original framework is capable of detecting certification testing procedure inefficiencies and analyzing the time and cost of flight testing. In this study, the framework’s capabilities are extended through advanced modeling techniques using Markov Chains and graph theory, extensive Monte Carlo simulations, and a broader application of design of Experiments to capture a wider range of variables and their impact on the noise testing outcomes and overall efficiency. Moreover, The enhanced framework quantifies and assesses the complexity level of testing procedures to provide insights on the associated uncertainty and risks. Additionally, it enables the prediction of process bottlenecks and establishes trade-offs more accurately. This work introduces enhanced decision support relying on different elements including sensitivity analyses, histogram overlays, and operational viewpoints. These capabilities allow stakeholders to interactively explore several noise testing strategies, compare their effectiveness and potential performance gains, and acquire insights on the resulting certification burden from different aspects. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Sensitivity analysis

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