检索结果-内蒙古大学图书馆

A Multi-Frequency Reflector Base Station Antenna With Enhanced Beam Scanning Capabilities for 6G

IEEE Antennas and Wireless Propagation Letters 2025年

作者： Xie, Yujie Wang, Zhengpeng Li, Yujian Miao, Jungang Gao, Steven Electromagnetic Laboratory School of Electronic and Information Engineering Beijing100191 China Beijing Jiaotong University Institute of Lightwave Technology and the Key Laboratory of All Optical Network and Advanced Telecommunication Network Ministry of Education Beijing100044 China Chinese University of Hong Kong Department of Electronic Engineering Hong Kong

This letter presents a multi-frequency base station antenna with enhanced beam scanning capabilities for high data rate 6 G communication. The antenna consists of a dual-polarized multi-frequency feed and a novel dual-cylindrical reflector antenna (DCRA). Through the rotation of the sub-reflector, which is illuminated by the feed, the beam can be scanned across a wide angle along the planar cylindrical orientation of the main reflector. This scanning process results in a beam scanning angle that is roughly twice the rotation angle of the sub-reflector. The phase center of the reflected beam from the sub-reflector is designed to coincide with the focal line of the main reflector, enabling two-dimensional focusing of the beam without loss of the scanning angle. A concise design formula based on the described antenna structure is derived, enabling the entire antenna design to follow a clear design flowchart, which incorporates a rapid method for determining the focal length product and focal point locations using near-field Fast Fourier Transform (FFT). The designed antenna achieves ±20° beam scanning coverage at 45 GHz, 100 GHz, and 220 GHz, with a gain exceeding 50 dBi at 220 GHz. Both simulation and experimental results validate the effectiveness of the proposed method. © 2002-2011 IEEE.

关键词： Antenna reflectors

来源：评论

学校读者我要写书评

暂无评论

Sequential hardening mechanisms in additive-manufactured NiTi shape memory alloys that can significantly delay compressive failure

引用

Materials Today 2025年

作者： Ma, Huwen Zhao, Yanchun Luo, Junhui Su, Yu Zheng, Tengfei Yu, Zhiqi Wu, Yuan Gao, Yanfei State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals School of Materials Science and Engineering Lanzhou University of Technology Lanzhou730050 China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing100083 China School of Advanced Materials and Nanotechnology Xidian University Xian710071 China Department of Materials Science and Engineering University of Tennessee KnoxvilleTN37996 United States

Most material design strategies devoted to the strength-ductility synergy in tension are based on the delay of the necking instability. However, the counterpart investigations under compression remain elusive. Recent developments in simulating the failure process reveal that microscopic voids or cavities under compression/shear-dominated loadings will evolve sequentially as flattened to a micro-crack, rotating and elongating into kinks, and then interacting and coalescing with neighboring micro-cracks. This entire process can be significantly slowed down if the matrix material sustains a high work hardening exponent. Motivated by this novel micromechanical understanding, this work successfully realized hierarchically heterostructured microstructures in NiTi shape memory alloys (SMA) by using the selective laser melting (SLM) additive manufacturing technique. It is the sequential or progressive transition from the martensitic phase transformation, to heterogeneous deformation induced hardening, and then to amorphous lamellae hardening at later stage that sustains a high work hardening rate which results into an exceptionally high failure strain of the as-fabricated (without post-treatment) SMA under compression. The occurrence of amorphization at high strains is attributed to the high dislocation density and to the oxygen-assisted energy barrier reduction. This work thus offers an unprecedent design approach for the development of high performance SMAs. © 2025 Elsevier Ltd

关键词： Strain hardening

来源：评论

学校读者我要写书评

暂无评论

Triangle Matters! TopDyG: Topology-aware Transformer for Link Prediction on Dynamic Graphs 25

Triangle Matters! TopDyG: Topology-aware Transformer for Lin...

引用

34th ACM Web Conference, WWW 2025

作者： Zhang, Xin Cai, Fei Zheng, Jianming Pan, Zhiqiang Chen, Wanyu Chen, Honghui Chen, Chonghao National Key Laboratory of Information Systems Engineering National University of Defense Technology Changsha China State Key Laboratory of Mathematical Engineering and Advanced Computing Wuxi China College of Electronic Countermeasures National University of Defense Technology Hefei China

ISBN: (纸本)9798400712746

Dynamic graph link prediction is widely utilized in the complex web of the real world, such as social networks, citation networks, recommendation systems, etc. Recent Transformer-based link prediction methods on dynamic graphs not only fail to model the fine-grained structures such as triangles with the vanilla Transformers in the graph serialization process, but also amplify the imbalanced distribution of graphs because of their over-estimation of high-degree nodes. To tackle these issues, we propose a Topology-aware Transformer on Dynamic Graph (TopDyG) for link prediction, consisting of a topology injected Transformer (Ti-Transformer) and a mutual information learning (Mi-Learning). The Ti-Transformer explores the explicit structure of serialized graphs, capturing the topological features. The Mi-Learning mines the relationship between nodes by modeling the mutual information with a prior knowledge, alleviating the over-estimation of high-degree nodes when applying the Transformer-based models for the dynamic graph link prediction task. Extensive experiments on four public datasets containing both transductive and inductive settings present the superiority of our proposal. In particular, TopDyG presents an improvement of 43.27% and 28.75% against the state-of-the-art baselines in terms of NDCG and Jaccard, respectively. The advantages are especially obvious on the high-density graphs. © 2025 Copyright held by the owner/author(s).

关键词： Recommender systems

来源：评论

学校读者我要写书评

暂无评论

Fabrication and Characterization of Polyurea-Polyurethane/Silver Bilayer Shell Phase Change Nanocapsules 154th

Fabrication and Characterization of Polyurea-Polyurethane/Si...

引用

154th Annual Meeting and Exhibition of The Minerals, Metals and Materials Society, TMS 2025

作者： Liu, Sitong Li, Tonghe Hu, Dengti Bai, Hao State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing 30# Xueyuan Road Beijing100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing 30# Xueyuan Road Beijing100083 China

ISBN: (纸本)9783031807473

Composite dual-layer shell phase change capsules have received atten tion due to their excellent thermal storage capacity, high thermal conductivity, and good thermal stability. In this study, a method combining in-situ polymerization and liquid-phase reduction was proposed to prepare polyurea-polyurethane organic phase change nanocapsules. Firstly, a polyurea-polyurethane shell is formed on the surface of the core material of butyl stearate through in-situ polymerization method. Afterwards, a layer of silver shell is formed on the surface of the previously prepared phase change capsules which have polyurea-polyurethane shell using the liquid ***,thepolyurea-polyurethane/silvershellphasechange nanocapsules are obtained. The volume encapsulation efficiency of the dual-layer shell phasechangenanocapsulespreparedreaches82.39%.Thethermalconductivity is 2.164 W/(m·K), indicating an improvement in thermal conductivity compared with the nanocapsules without the silver shell. After 1000 thermal cycles, minimal enthalpy loss during melting and solidification suggests excellent thermal reliability. © TheMinerals, Metals & Materials Society 2025.

关键词： Positive temperature coefficient

来源：评论

学校读者我要写书评

暂无评论

Effect of vanadium on the microstructure and high-temperature properties of 24CrNiMo coatings in direct laser deposition technology

引用

Journal of Materials Research and technology 2025年 36卷 6857-6873页

作者： Chao Zhang Qiang Fang Yan Liu Dengwen Hu Ying Wu Chuan Yang Lei Wang Hui Chen Key Laboratory of Advanced Technology of Materials Ministry of Education School of Materials Science and Engineering Southwest Jiaotong University Chengdu Sichuan 610031 China State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin 150001 China CRRC Changchun Railway Vehicles Co. Ltd. Changchun Jilin 130062 China

24CrNiMo low alloy steel is extensively used in the high-speed rail industry for brake discs due to its superior strength and plasticity. This study presents an effective method for extending the life of brake discs through repair and remanufacturing, addressing the challenge of insufficient performance in the high temperature. By incorporating varying ratios of V elements into 24CrNiMo low alloy powders, the high temperature performance of the brake discs was significantly enhanced, and the strengthening mechanisms and failure behavior at the high temperature of V elements were systematically analyzed. The results indicate that the addition of V elements slightly increases the phase transition temperature of the coating, refines the lath martensite, and promotes the formation of the VC. The microhardness, tensile strength, and elongation of the coatings improve significantly with increasing V content, primarily due to the combined effects of precipitation strengthening, solution strengthening, and fine-grained strengthening. However, adding excessive V results in brittle fracture and a marked reduction in the plasticity of the coatings due to the precipitation and growth of VC in the grain boundary. At 600 °C, the coatings with 0.5 % V content demonstrated the optimal balance between tensile strength and elongation, whereas excessive V content caused low ductility due to the precipitation and growth of the VC. This study highlights that the performance of the coatings can be effectively optimized by adjusting the V content in the high temperature, providing both theoretical support and practical guidance for the remanufacturing of brake discs.

关键词： 24CrNiMo The addition of V Microhardness The property of high temperature Precipitation strengthening Solution strengthening

来源：评论

学校读者我要写书评

暂无评论

Analysis of Spiral Scanning Amplitude Modulation Methods for Two-photon Endomicroscopy 10

Analysis of Spiral Scanning Amplitude Modulation Methods for...

引用

10th Symposium on Novel Optoelectronic Detection technology and Applications

作者： Cui, Haodong Wang, Conghao Liu, Huilan Zhang, Xiulei Hu, Yanhui Fu, Qiang Wu, Runlong Wang, Aimin Feng, Lishuang School of Instrumentation and Optoelectronic Engineering Beihang University Beijing100191 China Beijing100191 China School of Automation Science and Electrical Engineering Beihang University Beijing100191 China Beijing Transcend Vivoscope Biotech Co. Ltd. Beijing100049 China Beijing Key Laboratory for Optoelectronics Measurement Technology Beijing Information Science and Technology University Beijing100192 China State Key Laboratory of Advanced Optical Communication System and Networks Department of Electronics Peking University Beijing100871 China

ISBN: (数字)9781510688155

ISBN: (纸本)9781510688148

Two-photon endomicroscopy is a high-resolution label-free imaging technique for biological tissues. This paper analyzes sinusoidal and triangular amplitude modulation methods for spiral scanning two-photon endomicroscopy. In the theoretical modeling section, the mathematical model of PZT fiber scanner is established, and the distortion of fiber scanning trajectory caused by two amplitude modulated sine wave signals is simulated and evaluated. In the experimental verification section, a test platform is constructed to measure the scanning trajectory distortion driven by these amplitude modulated sine wave signals. Finaly, spiral scanning two-photon endomicroscopic imaging of in-vivo GFP mice brain tissues using sinusoidal amplitude modulated signals are demonstrated. © 2025 SPIE.

关键词： Amplitude modulation

来源：评论

学校读者我要写书评

暂无评论

Ultra-compact on-chip camera based on optoelectronic compound eyes with nonuniform ommatidia

引用

International Journal of Extreme Manufacturing 2025年第1期7卷 543-553页

作者： Lin Zhu Yu-Qing Liu Jia-Yi Wan Zhi-Juan Sun Dong-Dong Han Qi-Dai Chen Yong-Lai Zhang State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchunPeople’s Republic of China Zhejiang Laboratory HangzhouPeople’s Republic of China Center for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Emitting Materials and Technology of Ministry of EducationNational Demonstration Center for Experimental Physics EducationNortheast Normal UniversityChangchunPeople’s Republic of China

Compound eyes(CEs)that feature ultra-compact structures and extraordinary versatility have revealed great potential for cutting-edge ***,the optoelectronic integration of CEs with available photodetectors is still challenging because the planar charge-coupled device(CCD)/complementary metal oxide semiconductor(CMOS)detector cannot match the spatially distributed images formed by CE *** reach this end,we report here the optoelectronic integration of CEs by manufacturing 3D nonuniform ommatidia for developing an ultra-compact on-chip *** a proof-of-concept,we fabricated microscale CEs with uniform and nonuniform ommatidia through femtosecond laser two-photon photopolymerization,and compared their focusing/imaging performance both theoretically and *** engineering the surface profiles of the ommatidia at different positions of the CE,the images formed by all the ommatidia can be tuned on a *** this way,the nonuniform CE can be directly integrated with a commercial CMOS photodetector,forming an ultra-compact CE ***,we further combine the CE camera with a microfluidic chip,which can further serve as an on-chip microscopic monitoring *** anticipate that such an ultra-compact CE camera may find broad applications in microfluidics,robotics,and micro-optics.

关键词： artificial compound eyes two-photon photopolymerization optical electronic integration

来源：评论

学校读者我要写书评

暂无评论

Domain Adaptation-based Radio Frequency Fingerprint Identification for Industrial Cyber-Physical Systems

引用

IEEE Network 2025年

作者： Wang, Yatong Cao, Bin Wen, Zhongyi Yan, Mu Song, Changqing Beijing Institute of Technology School of Information and Electronics Beijing100081 China Beijing University of Posts and Telecommunications State Key Laboratory of Networking and Switching Technology Beijing100876 China University of Electronic Science and Technology of China School of Information and Communication Engineering Chengdu611731 China Laboratory of Electromagnetic Space Cognition and Intelligent Control Technology Beijing100191 China University of Electronic Science and Technology of China National Key Laboratory of Wireless Communications Chengdu611731 China Laboratory of Electromagnetic Space Cognition and Intelligent Control Beijing100191 China

With the widespread adoption of cloud and fog platforms, security issues facing Industrial Cyber-Physical Systems (ICPSs) are increasingly prominent. Radio Frequency Fingerprinting (RFFI) emerges as a promising physical layer security technique for user authentication, effectively enhancing ICPS security over wireless networks by exploiting inherenthardware imperfections in transmitters. However, as technologies evolve and user environments become denser and more complex, existing RFFI techniques encounter significant domain shift challenges, leading to performance degradation. Therefore, developing domain-adaptive RFFI techniques is crucial for the effectiveness of ICPSs. In this article, we first provide a comprehensive review of the RFFI framework, emphasizing its applications in ICPSs and the key processes involved. Next, we focus on the domain shift issues faced by RFFI in ICPSs and present a comprehensive survey of domain adaptation methods. To tackle these challenges, we propose a novel feature-alignment based domain adaptation (FADA) framework for RFFI, which is designed to mitigate the performance degradation caused bycross-domain shifts by aligning the feature representations of the source and target domain. Finally, we discuss the inherent challenges and future directions for developing domain adaptation based RFFI to enhance the security of ICPSs. © 2025 IEEE. All rights reserved.

关键词： Radio frequency identification (RFID)

来源：评论

学校读者我要写书评

暂无评论

Sintering, high-temperature stability, and thermal conductivity of (Zr, Nb, Hf, Ta)(C, N) high-entropy carbonitrides

引用

Ceramics International 2025年

作者： Bai, Yang Liang, Yuxin Bi, Juan Cui, Baoning Lu, Zhaopeng Wang, Huangxuan You, Xixi Li, Bangsheng School of Materials Science and Engineering Harbin Institute of Technology Harbin150001 China State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin150001 China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology Harbin150001 China

High-entropy carbonitrides (HECNs), a new class of high-performance ceramics, hold great potential for high-temperature structural materials and thermal protection systems due to their excellent thermal stability and properties. For its better application, it is important to optimize the sintering temperature of HECNs and deeply investigate its thermal conductivity behavior. This study systematically investigates the thermodynamic stability, formation ability, and thermal properties of (ZrHfNbTa)CxN1-x through first-principles calculations and experimental validation. Thermodynamic calculations reveal that nitrogen incorporation reduces the sintering temperature required to achieve a stable high-entropy solid solution. Experimental validation by spark plasma sintering (SPS) shows that the sintering temperature can be reduced from 1950 °C to 1700 °C. Ab initio molecular dynamics (AIMD) simulations demonstrate that HECNs retain structural integrity at 1773 K. Thermal conductivity tests show an increase with temperature, but a decrease with higher nitrogen content, which is mainly caused by the increased scattering of phonons resulting from lattice distortions. The Debye-Callaway model fitting further elucidates the underlying thermal conductivity mechanisms. In summary, nitrogen incorporation enhances the thermodynamic stability and reduces thermal conductivity of HECN ceramics, providing valuable theoretical and experimental support for their application in high-temperature structural materials and thermal protection systems. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Carbon nitride

来源：评论

学校读者我要写书评

暂无评论

Optimized design of chip-breaking geometry of insert for the high-stability indexable insert drill 3

Optimized design of chip-breaking geometry of insert for the...

引用

3rd International Conference on Electrical, Electronics, and Information engineering, EEIE 2024

作者： Jiang, Aisheng Wen, Juan Yu, RenChao Liu, Zhanqiang Wang, Shequan Zhao, Jinfu School of Mechanical Engineering Shandong University Jinan250061 China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Jinan250061 China Key National Demonstration Center for Experimental Mechanical Engineering Education Jinan250061 China Zhuzhou Diamond Cutting Tools Co. Ltd. Zhuzhou412007 China School of Mechanical Electrical & Information Engineering Shandong University Weihai264209 China

ISBN: (纸本)9781510688179

The chip morphology of indexable insert drills affects chip evacuation performance, which in turn influences the dimensional accuracy and surface quality of the workpiece. Simultaneously, the cutting force impacts the balance of radial forces, further affecting the dimensional accuracy and surface quality. Therefore, studying the effects of chip morphology and cutting force on the high stability applications of indexable insert drills is of significant importance. This paper proposes an optimized insert groove design for high-stability applications, focusing on cutting force and chip radius optimization. First, based on the cutting principles of indexable insert drills, insert groove parameters were selected, and an orthogonal experimental scheme was designed. key parameters affecting chip radius and cutting force were determined through simulation experiments. Second, the parameters were ranked by their influence on chip radius and cutting force, and the optimal parameter combinations were identified. Finally, the feasibility of the optimized insert groove design was verified through experiments. © The Authors.

关键词： Drills

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：