检索结果-内蒙古大学图书馆

Mechanical properties and flow stress constitutive relationship of Ti–6Al–4V alloy with equiaxed microstructure at cryogenic temperatures

引用

Chinese Journal of Aeronautics 2025年第1期38卷 365-379页

作者： Jingwen HU Xun CHEN Yashun WANG Chen YANG College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China Laboratory of Science and Technology on Integrated Logistics Support National University of Defense TechnologyChangsha 410073China

This paper investigates the uniaxial tensile mechanical properties and flow behavior of Ti-6Al-4V alloys with equiaxed microstructure at cryogenic temperatures ranging from 77 K to298 K and strain rates from 10^(-4)/s to 10^(-2)/*** electron microscopy is utilized to analyze the fracture morphology,aiming to reveal the fracture behavior at various *** applicability of the Zener-Hollomon parameter and the Johnson-Cook model in describing the flow stress of Ti-6Al-4V at cryogenic temperatures is ***,a constitutive relationship modeling method based on the variational recurrent networks is *** test results show a significant increase in the strength of equiaxed Ti-6Al-4V alloy under cryogenic conditions while the plastic deformation process is ***,the fracture analysis indicates that even at 77 K,the fracture process is still dominated by ductile fracture,and brittle fracture does not occur within the range of 77 K to 298 *** fitting results validate the performance of the Zener-Hollomon parameter and the Johnson-Cook model in describing the deformation flow stress of Ti-6Al-4V alloy at cryogenic *** results also indicate that the proposed constitutive relationship modeling method based on the variational recurrent network performs better,making it a potential method for widespread applications.

关键词： Titanium alloys Mechanical properties Cryogenics Fracture testing Flow behavior

来源：评论

学校读者我要写书评

暂无评论

Design and Performance Study of Dielectric Elastomer-Driven Conical Tunable Soft Lens 10

Design and Performance Study of Dielectric Elastomer-Driven ...

引用

10th Symposium on Novel Optoelectronic Detection technology and Applications

作者： Hu, Zhuoqun Zhang, Meng Gan, Zihao Lv, Jianming Liu, Zhaoyang Yang, Minghao Hong, Huajie College of Intelligent Science National University of Defense Technology Changsha410073 China Laboratory of Science and Technology on Integrated Logistics Support National University of Defense Technology Changsha410073 China

ISBN: (数字)9781510688155

ISBN: (纸本)9781510688148

This paper presents a tunable lens driven by dielectric elastomers, utilizing PDMS (polydimethylsiloxane) as the filling material. By designing a conical dielectric elastomer membrane to deform the PDMS material, the lens curvature can be altered to adjust the focal length. Through processes such as membrane stretching, electrode coating, PDMS curing, and assembly packaging, a tunable soft lens sample with an optical aperture of 10mm was fabricated. Finally, experiments were designed to test the performance of the lens sample. The results indicate that under the control of dynamic driving voltage signals, the dielectric elastomer-driven tunable soft lens can achieve a focal length variation from 46.9mm to 83.6mm, maintaining good imaging quality at different focal lengths. © 2025 SPIE.

关键词： Polydimethylsiloxane

来源：评论

学校读者我要写书评

暂无评论

Design of drag reduction and water pressure resistant skin layer of underwater vehicle based on mechanical metamaterials 10

Design of drag reduction and water pressure resistant skin l...

引用

2024 10th International Forum on Manufacturing technology and Engineering Materials, ICMTEM 2024

作者： Zhong, Chuxiang Cai, Li Mao, Yibin Yang, Kaiwen Yang, Xiaokang Yu, Dianlong College of Intelligence Science National University of Defense Technology Changsha410073 China Laboratory of Science and Technology on Integrated Logistics Support National University of Defense Technology Changsha410073 China

Developing high-speed and large working depth underwater vehicles has gradually become a hot topic. Various drag-reduction skins and water pressure-resistant structures have been proposed to reduce surface resistance interference and increase the working water depth. Mechanical metamaterials can exhibit extraordinary static mechanical and quasi-static mechanical properties. It provides possibilities for achieving excellent static water pressure resistance and drag reduction simultaneously. This paper proposed an underwater elastic skin based on metamaterials and drag-reducing grooves. A composite functional skin was obtained by combining the negative Poisson's ratio design of metamaterials with the V-groove drag reduction design. Analysis based on the COMSOL finite element simulation shows that lower flow resistance during high-speed and low-speed navigation and stronger pressure resistance can be achieved simultaneously. By comparing different drag reduction models, the drag reduction characteristics of the composite skin are analyzed. The results provide new ideas for the design of thin-layer multifunctional integrated underwater skins for UUV. © Published under licence by IOP Publishing Ltd.

关键词： Drag reduction

来源：评论

学校读者我要写书评

暂无评论

Innovative Design of Pressure-Resistant-Drag Reduction Skin Based on Mechanical Metamaterials

Innovative Design of Pressure-Resistant-Drag Reduction Skin ...

引用

International Conference on Applied Nonlinear Dynamics, Vibration and Control, ICANDVC 2024

作者： Mao, YiBin Jia, Qi Yang, KaiWen Yang, XiaoKang Zhong, ChuXiang Yu, DianLong Laboratory of Science and Technology on Integrated Logistics Support National University of Defense Technology Changsha410073 China College of Intelligence Science and Technology National University of Defense Technology Changsha410073 China

ISBN: (纸本)9789819633166

Aiming at the problems of high flow resistance, large mass, and weak pressure resistance in the traditional skin structure, this paper constructs a new type of pressure-resistant-drag reduction skin based on the bionic microgroove drag reduction technology and the theory of mechanical metamaterials. It analyzes and calculates its pressure resistance and drag reduction ability based on the finite element method. The results show that the flexible skin supported by the negative Poisson's ratio structure has a drag reduction rate of 2.75% higher than that supported by the traditional frame structure. On this basis, the drag reduction rate is used as an index to analyze the drag reduction performance of the skin under different honeycomb concave angle parameters and different sailing speeds. The results show that the flexible skin shows the highest drag reduction rate at 70°, while the drag reduction effect at other angles is greatly weakened, and even the resistance is increased. When the honeycomb concave angle is 70°, the drag reduction rate increases with the speed increase. At the same time, in terms of pressure resistance, the performance of the new skin is also significantly better than that of the traditional flexible skin. The mass is only 19.8% of the solid flexible skin structure and can withstand hydrostatic pressure of more than 10,000 m water depth. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： Metamaterials

来源：评论

学校读者我要写书评

暂无评论

Bragg scattering-driven anisotropic metabeam with multi-scale architecture for ultra-broadband vibration suppression at high structural stiffness

引用

Engineering Structures 2025年 336卷

作者： Jia, Qi Zhang, Jinhao Han, Donghai Wen, Jihong Yu, Dianlong College of Intelligence Science and Technology National University of Defense Technology Changsha410073 China Laboratory of Science and Technology on Integrated Logistics Support National University of DefenseTechnology Changsha410073 China

Despite advancements in metamaterial beams, practical applications remain limited by narrow bandgaps, excessive mass, and stiffness compromises. This study presents a single-phase lightweight anisotropic metabeam leveraging Bragg scattering and hierarchical architecture optimization to achieve concurrent ultra-low frequency and ultra-broadband vibration suppression while preserving high stiffness. A novel non-locality homogenization method (NLHM) integrating variational asymptotic formulations and continuum mechanics is developed, enabling efficient prediction of static-dynamic properties with more than 90 % computational efficiency gain over traditional finite element method. Experimental characterization reveals triaxial stiffness anisotropy (x/z-direction modulus exceeding y-direction by 41.2 times and 56.8 times) and triphasic Poisson's ratio behavior (–0.05 ≤ ν ≤ 0.42). Strategic exploitation of wave polarization in anisotropic media facilitates tri-modal vibration attenuation, achieving record relative bandwidths (ΔG) of 188.2 % (P-wave), 174.1 % (SH-wave), and 192.8 % (SV-wave). The metabeam demonstrates up to 59.8 dB peak attenuation and nearly 95 % wave confinement efficiency validated through laser vibrometry. This work establishes a paradigm for engineering multifunctional metamaterials through microstructure-mediated anisotropy, advancing the design of lightweight, high-stiffness vibration control systems. © 2025 Elsevier Ltd

关键词： Poisson ratio

来源：评论

学校读者我要写书评

暂无评论

A risk-graded propagation and dynamic recovery algorithm for optimizing supply chain networks

引用

Chaos, Solitons and Fractals 2025年 197卷

作者： Wu, Leilei Ding, Xixi Bai, Guanghan Yu, Liyan Xia, Yongxiang School of Communication Engineering Hangzhou Dianzi University Hangzhou310018 China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligent Science National University of Defense Technology Changsha410073 China Zhejiang Vocational Academy of Art Hangzhou310059 China

Supply chain networks are highly susceptible to systemic failures when faced with localized risk shocks due to their complexity and high interconnectivity. In this paper, a multi-state model for supply chain risk transmission and recovery is constructed. By introducing hierarchical infection probabilities (α(n,f)) and recovery probabilities (μ(n,f,R)), the node states are dynamically updated, taking into full account node attributes such as risk levels, node fitness, and recovery costs. Notably, a handling strategy for node failures is designed. When a node enters the failure state (the D state), the impacts on the network topology and the states of neighboring nodes are analyzed in detail. Corresponding measures are taken, including removing the failed node and its connections and updating the states of neighboring nodes based on their degrees and impact factors. At the same time, a reconnection mechanism for healthy nodes is designed to reduce network fragmentation and maintain network connectivity and stability. Through simulations and empirical data analysis, the model effectively limits the spread of risk, reduces the failure rate of high-risk nodes, and enhances the overall connectivity of the network. It performs well in different network topologies, providing valuable insights and practical tools for optimizing risk management in complex supply chains. © 2025

关键词： Complex network Risk management Risk transmission SIR model Supply chain management

来源：评论

学校读者我要写书评

暂无评论

Joint Task Partitioning and Resource Allocation in UAV-Enabled Vehicular Edge Computing Based on Deep Reinforcement Learning

引用

IEEE Internet of Things Journal 2025年第11期12卷 15453-15466页

作者： Liang, Hongbin Zhang, Han Ale, Laha Hong, Xintao Wang, Lei Jia, Qiong Zhao, Dongmei Southwest Jiaotong University School of Transportation and Logistics National United Engineering Laboratory of Integrated and Intelligent Transportation National Engineering Laboratory of Integrated Transportation Big Data Application Technology Chengdu611756 China Southwest Jiaotong University School of Computing and Artificial Intelligence Chengdu611756 China Southwest Jiaotong University School of Information Science and Technology Chengdu611756 China Chinese Academy of Sciences Laboratory of Noise and Vibration Research Institute of Acoustics Beijing100190 China McMaster University Department of Electrical and Computer Engineering HamiltonONL8S 4K1 Canada

Vehicle Edge Computing (VEC) leverages compact cloud computing at the mobile network edge to meet the processing and latency needs of vehicles. By bringing computation closer to the vehicles, VEC reduces data transmission, minimizes latency, and boosts performance for compute-intensive applications. However, during peak hours of urban road traffic, the scarce computational resources available at edge servers could pose challenges in fulfilling the processing needs of vehicles. Introducing Unmanned Aerial Vehicles (UAVs) as supplementary edge computing nodes could significantly mitigate the aforementioned issue. In this paper, we propose a flexible edge computing framework in which a fleet of UAVs function as mobile computational service providers, offering computation offloading services to multiple vehicles. We design and optimize a computation offloading model for the UAV-enabled vehicle edge computing environment. The proposed model tackles the task offloading challenge, aiming to optimize UAV revenue and task processing efficiency while considering the constraints of UAVs' restricted computational power and energy resources. Towards this end, our model jointly considers two key factors: task partitioning and computational resource allocation. To tackle the challenges posed by the aforementioned non-convex optimization problem, we construct a Markov Decision Process (MDP) model for the multi-UAV-enabled mobile edge computing system and introduce an innovative Multi-Agent Deep Reinforcement Learning (MADRL) framework addressing the decision-making challenge represented by MDP model. Comprehensive simulation outcomes illustrate that our devised task offloading technique outperforms other optimization methods. © 2014 IEEE.

关键词： Convex optimization

来源：评论

学校读者我要写书评

暂无评论

Distributed Framework Construction for Affine Formation Control

arXiv

引用

arXiv 2025年

作者： Li, Huiming Chen, Hao Wang, Xiangke Li, Zhongkui Shen, Lincheng College of Intelligence Science and Technology National University of Defense Technology Changsha410073 China Laboratory of Science and Technology on Integrated Logistics Support National University of Defense Technology Changsha410073 China The State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China

In affine formation control problems, the construction of the framework with universal rigidity and affine localizability is a critical prerequisite, but it has not yet been well addressed, especially when additional agents join the formation or link/agent failures emerge. Motivated by this observation, we investigate the problem of constructing affine formation frameworks in three scenarios, including vertex addition, edge deletion and vertex deletion. Our approach starts from the original affine formation and uses geometric methods to locally adjust the structure of the weighted graph to describe the topology, so that the modified framework maintains the universal rigidity and affine localizability. Notably, the developed strategies only utilize local measurements and exhibit distributed characteristics, laying the foundation for applications in multi-agent systems. To demonstrate the compatibility with affine formation control proposals, we present a case study on affine formation tracking in a multi-UAV formation, demonstrating the effectiveness of our algorithms in constructing eligible frameworks in aforementioned scenarios. Moreover, a comparative simulations is also conducted to highlight the low time complexity of our distributed algorithm relative to the centralized optimization-based method. Copyright © 2025, The Authors. All rights reserved.

关键词： Rigidity

来源：评论

学校读者我要写书评

暂无评论

Cavity-enhanced infrared quantum dot homojunction arrays

引用

Photonics Research 2025年第6期13卷 1497-1509页

作者： Naiquan Yan Feng Shi Xiaomeng Xue Kenan Zhang Cheng Huo Menglu Chen School of Optics and Photonics Beijing Institute of Technology Beijing 100081 China Zhejiang Key Laboratory of 3D Micro/Nano Fabrication and Characterization Westlake Institute for Optoelectronics Hangzhou 311421 China Laboratory of Science and Technology on Integrated Logistics Support Changsha 410073 China State Key Laboratory of Materials for Integrated Circuits Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China National Key Laboratory on Near-Surface Detection Beijing 100012 China

Infrared spectroscopy has wide applications in the medical field, industry, agriculture, and other areas. Although the traditional infrared spectrometers are well developed, they face the challenge of miniaturization and cost reduction. Advances in nanomaterials and nanotechnology offer new methods for miniaturizing spectrometers. However, most research on nanomaterial-based spectrometers is limited to the visible wavelength or near infrared region. Here, we propose an infrared spectrometer based on diffraction gratings and colloidal quantum dot (CQD) homojunction photodetector arrays. Coupled with a Fabry-Perot cavity, the CQD photodetector covers the 1.4–2.5 μm spectral range, with specific detectivity 4.64 × 10 11 Jones at 2.5 μm at room temperature. The assembled spectrometer has 256 channels, with total area 2.8 mm × 40 mm . By optimizing the response matrix from machine learning algorithms, the CQD spectrometer shows high-resolution spectral reconstruction with a resolution of approximately 7 nm covering the short-wave infrared.

关键词： Detector arrays Diffraction gratings Fourier transform infrared spectroscopy Imaging systems Medical fields Near infrared

来源：评论

学校读者我要写书评

暂无评论

Testability integrated evaluation method based on testability virtual test data

引用

Chinese Journal of Aeronautics 2014年第1期27卷 85-92页

作者： Liu Guanjun Zhao Chenxu Qiu Jing Zhang Yong Science and Technology on Integrated Logistics Support Laboratory National University of Defense Technology

Testability virtual test is a new test method for testability verification, which has the advantages such as low cost, few restrictions and large sample of test data. It can be used to make up the deficiency of testability physical test. In order to take the advantage of testability virtual test data effectively and to improve the accuracy of testability evaluation, a testability integrated eval- uation method is proposed in this paper based on testability virtual test data. Considering the char- acteristic of testability virtual test data, the credibility analysis method for testability virtual test data is studied firstly. Then the integrated calculation method is proposed fusing the testability vir- tual and physical test data. Finally, certain helicopter heading and attitude system is presented to demonstrate the proposed method. The results show that the testability integrated evaluation method is feasible and effective.

关键词： Data fusion Fault detection integrated evaluation Testability verification Virtual test

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：