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The influence of void and fractured fiber defects on the ultrafine Z-pin and Mode I fracture toughness of CFRP laminates

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Composite Structures 2025年 366卷

作者： Fu, Yihan Zhu, Weidong Li, Shuran Li, Mengze Xiao, Jing Yan, Ling Cheng, Liang Ke, Yinglin State Key Laboratory of Fluid Power and Mechatronic System School of Mechanical Engineering Zhejiang University Hangzhou310027 China Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province School of Mechanical Engineering Zhejiang University Hangzhou310027 China

To minimize the damage caused by Z-pin insertion to the in-plane properties of the laminate, researchers have initiated investigations into the utilization of fine Z-pins and reduced insertion densities. However, the manufacturing process of fine Z-pins introduces voids and fiber fracture defects, leading to a decline in Z-pin quality and consequently affecting the efficacy of interlaminar toughening. In this research, defects in the Z-pin preparation process were identified through extensive experiments, and pre-stressing is applied during the curing of the Z-pin, leading to the successful development of the high-quality 80 μm and 90 μm diameter Z-pins. Furthermore, this research extensively examines the impact of these two defects on the quality of Z-pins and provides a model to determine the optimal Z-pin size corresponding to various insertion depths under the existing processing conditions. For example, according to the model, the optimal Z-pin size for laminates with a thickness of 4 mm is 90 μm. This ensures that the Z-pin's failure mode remains at the critical transition between pull-out and fracture, thereby maximizing its tensile strength utilization. The research findings are validated through experimental verification, thus providing insights for the application of ultrafine Z-pins. © 2025 Elsevier Ltd

关键词： Fracture toughness

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Wideband Channel Measurement and Characterization Based on 5G Passive Sounding in Railway Scenarios

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China Communications 2025年第4期22卷 13-26页

作者： Zheng Peng Fei Dan Chen Chen Chen Haoran Huang Yanyan Ai Bo School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China State Key Laboratory of Advanced Rail Autonomous Operation Beijing Jiaotong UniversityBeijing 100044China Nanjing Rongcai Transportation Technology Research Institute Co. LtdNanjing 211121China Frontiers Science Center for Smart High-Speed Railway System Beijing Jiaotong UniversityBeijing 100044China

With the development of wireless communication,the fifth generation mobile communication technology(5G)has emerged as a hot topic in highspeed railway communication system and has moved towards industrial *** the radio propagation characteristics in 5G high-speed train(HST)scenarios is essential for enhancing wireless coverage and overall system *** propose a novel 5G passive sounding scheme to extract channel impulse responses(CIRs)using channel state information reference signals(CSI-RS)from the target 5G base station(BS).Detailed procedures for timefrequency synchronization,CSI-RS detection and extraction are presented through *** the laboratory work involving absolute power calibration,phase coherence calibration and power delay profile(PDP)validation,we validate the accuracy and performance of the developed ***,a measurement campaign was conducted in HST scenarios encompassing both residential and undeveloped *** path loss(PL)model and the channel characteristics including stationarity interval(SI),multipath components(MPCs),shadow fading(SF),Rician K-factor,root mean square(RMS)delay spread and received correlation coefficients are analyzed and *** estimated channel characteristics and the statistical model presented in this paper will contribute to the research on HST radio propagation and the development of 5G railway communication systems.

关键词： 5G channel characterization channel measurement high-speed train passive sounding

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Highly selective[4+4]cross-photodimerization of(4a-azonia)anthracenes driven by confinement of D-A hetero-guest pair in cucurbituril host

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Chinese Chemical Letters 2025年第3期36卷 263-266页

作者： Xianchen Hu Junli Yang Fang Gao Zhiyong Zhao Simin Liu School of Chemistry and Chemical Engineering Wuhan University of Science and TechnologyWuhan 430081China The State Key Laboratory of Refractories and Metallurgy Institute of Advanced Materials and NanotechnologyWuhan University of Science and TechnologyWuhan 430081China

The cross-photodimerization often comes with the formation of undesired and competitive homophotodimer as side ***,we report a series of highly selective[4+4]cross-photodimerization between anthracene and 4a-azoniaanthracene derivatives within a cucurbit[10]uril(CB[10])host in *** inclusion complexes were formed through encapsulation of donor(D1-D2,anthracene derivative)and acceptor(A1-A3,4a-azoniaanthracene derivatives)pairs in CB[10].In the presence of CB[10](1.0 equiv.),the[4+4]cross-photodimerization between D1 and A1/A2/A3 efficiently gave a single racemic ***,the cross-photodimerization between 9-substituted anthracene D2 and A1/A3 was catalyzed by CB[10](0.1 equiv.)to quantitatively yield a cross-photodimer with high *** formation of selective cross-photodimers could be attributed to the exclusive encapsulation of D-A hetero-guest pairs in CB[10]and the confinement effect of the CB[10]host *** study further proves host–guest complexation as a powerful strategy for cross-cycloaddition reactions with high efficiency.

关键词： Supramolecular catalysis Cross-photodimerization Host-guest complexation Charge-transfer interaction Cucurbituril

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A novel cross-lamellar deformation mechanism through α2 ↔ γ bidirectional phase transformation in a γ-TiAl alloy

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Scripta Materialia 2025年 264卷

作者： Liang, He Ding, Hongsheng Xu, Xuesong Zhang, Xuxing Chen, Ruirun Guo, Jingjie Fu, Hengzhi National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and Engineering Harbin Institute of Technology Harbin150001 China Jiangsu Belight Laboratory State Key Laboratory of Advanced Casting Technologies School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing210094 China

Cross-lamellar deformation is hard to be activated because of the obstruction of α2/γ interface to dislocations in the lamellar TiAl alloy. In the present work, continuous shear across the lamellar interface was achieved through twinning and α2 ↔ γ bidirectional phase transformation during high-temperature tensile deformation. The {202‾1} α2 twins were induced by the stress concentration at the tips of γ twins in adjacent lamellae and propagated through the nanoscale (α2 + γ) lamellae (γ → α2T), followed by the nucleation and growth of γ phase inside α2 twins (α2T → γ). The existence of Blackburn orientation relationship between α2 twin and γ inside it, as well as the Al-rich stacking faults in α2 twins, provide strong evidence for this bidirectional phase transformation. These findings offer an innovative understanding for the coordinated deformation of (α2 + γ) lamellar structures and provide a new sight for improving the deformation capacity of TiAl alloys. © 2025

关键词： Titanium alloys

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Preparation of high-purity iron phosphate from laterite pressure leaching residue and wastewater treatment: Kinetics and applications

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Process Safety and Environmental Protection 2025年 197卷

作者： Cao, Zhihe Jin, Cian Ma, Baozhong Zhang, Chengfa Chen, Yongqiang Wang, Chengyan State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing100083 China

In recent years, the rapid expansion of the renewable energy sector has driven a substantial surge in the demand for nickel, a critical raw material. As nickel sulfide ore reserves continue to diminish, laterite nickel ores have emerged as the predominant source, accounting for over 70 % of global nickel production. Nitric acid pressure leaching (NAPL) was invented to treat laterite nickel ores for the comprehensive recovery of valuable components. In NAPL process, the resulting residue after extracting nickel and cobalt from laterite nickel ore is enriched with valuable metal resources, particularly iron (with an iron content exceeding 60 %). This paper focuses on the preparation of high-purity iron phosphate from laterite NAPL residue and the efficient recycling of process wastewater. Initially, phosphoric acid is employed as leaching agent to remove impurities from the NAPL residue while simultaneously converting Fe2O3 into FePO4·2H2O. For the treatment of the pre-leachate, iron is precipitated first, followed by the enrichment of chromium and aluminum. The optimal conditions are a temperature of 70 °C and a duration of 2.5 h, achieving removal efficiency of 96.12 % for chromium and 90.43 % for aluminum. Iron and phosphorus are recycled in the forms of crude iron phosphate and crude phosphoric acid, respectively. The crude iron phosphate was dissolved and induced precipitation as pure iron phosphate, which exhibits excellent electrochemical performance. The kinetics of iron extraction from the transformed residue were investigated, revealing that the mixed control model provides the best fit for the process. The activation energy of the mixed control model was found to be 31.92 kJ/mol. This process not only concentrates the impurity elements chromium and aluminum but also ensures the efficient utilization of iron and phosphorus components. The proposed method holds significant potential for mitigating environmental challenges associated with the accumulation and

关键词： Nickel smelting

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Design of High-efficiency Transmitarray with Beam Steering and Low Scattering Characteristic

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IEEE Transactions on Antennas and Propagation 2025年

作者： Shaozhi, Wang Zihao, Zheng Weiwei, Wu Yuhong, Ma Jingjian, Huang Qingzhan, Shi Naichang, Yuan National University of Defense Technology State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Hunan Changsha410000 China National University of Defense Technology College of Electronic Engineering Hefei230037 China

This article introduces a hybrid design method for high-efficiency absorbing Reconfigurable Transmitarray (ARTA). By cascading an absorbing layer with a 2-bit reconfigurable layer, the transmission unitcells can realize the frequency response characteristic of an Absorbing-Transmissive-Absorbing (A-T-A). Specifically, the frequencies with an absorption rate exceeding 80% are within the ranges of 3.3GHz-5.1GHz and 7.8GHz-9.4GHz, while the frequency range with transmission exceeding -3dB spans from 5.69GHz to 5.92GHz. Meanwhile, the transmission phase can be adjusted among four states: 0°, 90°, 180°, and 270°, enabling beam steering of ARTA. Compared to designs for non-reconfigurable transmissive arrays, our design methodology necessitates the satisfaction of absorbing performance under different phase states. For validation, A prototype sample, comprising a 12x12 array structured with 5 metallic layers and 4 dielectric layers, sandwiching an air layer in between, has been fabricated and tested. Measurement results demonstrated high radiation performance with a peak gain of 21.6 dB and aperture efficiency of 33.3% at 5.85 GHz. The BW-1 dB and BW-3 dB were 0.2 GHz and 0.6 GHz, respectively. ±60° 2D-scanning was achievable and when the beam is directed at 0°, the sidelobe levels in the E-plane and H-plane are -17.3 dB and -18 dB, respectively. Under normal incidence of an x-polarized wave, the -8 dB Monostatic RCS reduction bandwidths covered 32.1% (3.4-4.7 GHz) for lower band and 10% (8.5-9.4 GHz) for upper band. The ARTA by this hybrid design methodology represents an attractive solution for addressing electromagnetic compatibility issues and for low-detectability applications. © 1963-2012 IEEE.

关键词： Integrated circuit design

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Fabrication and characterization of mullite fiber-based porous ceramics with mixed fiber lengths for high-temperature gas filtration

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Ceramics International 2025年

作者： Zheng, Dazhi Zhu, Ruijian Hu, Yuwen Liang, Shiou Sun, Huiying Wang, Zengmei State Key Laboratory of Engineering Materials for Major Infrastructure Jiangsu Key Lab. of Construction Materials School of Materials Science and Engineering Southeast University Nanjing211189 China School of Materials Science and Engineering Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Nanjing Institute of Technology Nanjing211167 China

The emissions and particulate pollutants (PM) from industrialization and other human activities have become a significant threat to human health. Researchers have experimented with various fiber-bonded filters, but there are still relatively few products with good high-temperature resistance. In this paper, a fiber-bonded porous ceramic with high porosity was prepared by vacuum filtration combined with freeze-drying using two homemade mullite fibers with different length-to-diameter ratios as raw materials and mullite sol as binder. When the content of fine fibers is 40 %, the product has a better overall performance, its density is 0.63g/cm3, porosity is 74 %, strength is 0.77 MPa, thermal conductivity is 0.153 W m−1 K−1. When the airflow rate of 2 L/min, the pressure drop is 80 Pa, the filtration efficiency of about 99 %, the QF is 0.08 pa−1, The mullite fiber-bonded porous ceramics prepared through a simple process exhibit excellent filtration performance, offering a wide range of potential applications. © 2025

关键词： Thermal conductivity of gases

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Ti deficiency and its effect on synthesizing all-d-metal Heusler alloy powders via mechanical alloying

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Materials Characterization 2025年 224卷

作者： Zhang, Hongguo Shi, Jinhao Zhang, Zhentao Wang, Xiangming Yue, Ming College of Materials Science and Engineering State Key Laboratory of Materials Low-Carbon Recycling Key Laboratory of Advanced Functional Materials Ministry of Education Beijing University of Technology Beijing100124 China Hefei230031 China

This study proposes and realizes the synthesis of powder and bulk Ni-Co-Mn-Ti-based all-d-metal Heusler alloys through mechanical alloying and powder metallurgy. Ti deficiency was found and recognized as a critical factor for the phase formation in similar compounds. By adjusting the Ti content, alloying and heat treatment process, L10, B2, and 5 M martensitic phases can be obtained. Martensitic phase transformation temperatures can also be adjusted through various factors involved in the process. The absence of a metamagnetic transition up to 3 T was observed in the bulk samples, which is related to the small magnetization difference during the phase transformation. A maximum magnetic entropy change comparable to alloys produced via rapid quenching was achieved. The present method is an effective and flexible route to fabricating powders of all-d-metal alloys with tailored structural and magnetic properties. It can serve as a pre-process for advanced manufacturing and provide new phase control choices in related systems. © 2025 Elsevier Inc.

关键词： Titanium alloys

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Lensless efficient snapshot hyperspectral imaging using dynamic phase modulation

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Photonics Research 2025年第2期13卷 511-526页

作者： CHONG ZHANG XIANGLEI LIU LIZHI WANG SHINING MA YUANJIN ZHENG YUE LIU HUA HUANG YONGTIAN WANG WEITAO SONG Beijing Engineering Research Center of Mixed Reality and Advanced Display School of Optics and Photonics Beijing Institute of Technology Zhengzhou Research Institute Beijing Institute of Technology State Key Laboratory of Radio Frequency Heterogeneous Integration College of Physics and Optoelectronic Engineering Shenzhen University School of Computer Science and Technology Beijing Institute of Technology School of Electrical and Electronic Engineering Nanyang Technological University School of Artificial Intelligence Beijing Normal University

Snapshot hyperspectral imaging based on a diffractive optical element(DOE) is increasingly featured in recent progress in deep optics. Despite remarkable advances in spatial and spectral resolutions, the limitations of current photolithography technology have prevented the fabricated DOE from being designed at ideal heights and with high diffraction efficiency, diminishing the effectiveness of coded imaging and reconstruction accuracy in some bands. Here, we propose, to our knowledge, a new lensless efficient snapshot hyperspectral imaging(LESHI)system that utilizes a liquid-crystal-on-silicon spatial light modulator(LCoS-SLM) to replace the traditionally fabricated DOE, resulting in high modulation levels and reconstruction accuracy. Beyond the single-lens imaging model, the system can leverage the switch ability of LCoS-SLM to implement distributed diffractive optics(DDO)imaging and enhance diffraction efficiency across the full visible spectrum. Using the proposed method, we develop a proof-of-concept prototype with an image resolution of 1920 × 1080 pixels, an effective spatial resolution of 41.74 μm, and a spectral resolution of 10 nm, while improving the average diffraction efficiency from 0.75 to0.91 over the visible wavelength range(400–700 nm). Additionally, LESHI allows the focal length to be adjusted from 50 mm to 100 mm without the need for additional optical components, providing a cost-effective and timesaving solution for real-time on-site debugging. LESHI is the first imaging modality, to the best of our knowledge,to use dynamic diffractive optics and snapshot hyperspectral imaging, offering a completely new approach to computational spectral imaging and deep optics.

关键词： Diffraction efficiency Diffractive optical elements Imaging systems Phase modulation Spatial light modulators Spatial resolution

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Fabrication of bifocal curved compound eyes for large-DOF and wide-FOV imaging via femtosecond laser 3D printing

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Optics Communications 2025年 585卷

作者： An, Ran Hu, Zhi-Yong Zhang, Zi-Heng Jin, Xue-Tao Liu, Xue-Qing Wang, Yan Yu, Yan-Hao Chen, Qi-Dai State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun130012 China Key Laboratory of Advanced Structural Materials of Ministry of Education Changchun University of Technology Changchun220103 China

Miniature imaging systems are pivotal in applications such as medical endoscopes, micro-robotics, virtual reality, and military reconnaissance. Nonetheless, achieving both an extended depth of field and a broad field of view in compact imaging devices remains a significant challenge. In nature, the sub-eye of trilobite compound eye exhibits a remarkable structure that focuses incoming light onto two distinct focal planes, enabling the simultaneous detection of both proximate and distant objects. Drawing inspiration from trilobite compound eye, this study introduces an innovative bioinspired design featuring a bifocal curved compound eye, offering an enhanced depth of focus and an expansive field of view. Meanwhile, the focal lengths of sub-lenses with varying orientations are meticulously designed to ensure convergence on a common imaging plane, thereby addressing the challenge of detector reception. The compound lens is manufactured through femtosecond laser 3D printing technology to achieve high-fidelity profiles that match the design. Experimental results demonstrate that the compound lens can concurrently capture images with a 90° field of view from near (10 cm) objects, without the need for mechanical zoom mechanisms. This breakthrough provides fresh perspectives for future applications in micro-vision technologies, including medical diagnostics and reconnaissance robotics. © 2025

关键词： Femtosecond lasers

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