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Nanoimprint lithography-assisted block copolymer self-assembly for hyperfine fabrication of magnetic patterns based on L10-FePt nanoparticles

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Science China Chemistry 2025年

作者： Jie Zhang yi chen Guijun Li Zelin Sun Zhengong Meng Wai-Yeung Wong Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy The Hong Kong Polytechnic University The Hong Kong Polytechnic University Shenzhen Research Institute Division of Integrative Systems and Design and Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology School of Flexible Electronics (Future Technology) and Institute of Advanced Materials (IAM) Nanjing Tech University

L10-FePt-type bit-patterned media has provided a promising alternative for ultrahigh-density magnetic recording systems in the current digital era, but rapid fabrication of magnetic patterns with hyperfine bit islands is still challenging, especially with the target for miniaturization and scalable production simultaneously. Herein, Fe,Pt-containing block copolymers were utilized as single-source precursors for solution-processable patterning and subsequent generation of the demanding magnetic FePt dots by in situ pyrolysis. High-throughput nanoimprint lithography was initially employed to fabricate the predefined bit cells precisely,and then the intrinsic self-assembly of phase-separated block copolymers further drove the formation of accurate bit *** from the synergistic effect of top-down lithographic approach and bottom-up self-assembly, the customizable patterns could be achieved for large-scale mass production in targeted areas, but high-density isolated dots could also be accurately aligned along the patterned features after subsequent self-assembly. This reliable strategy would provide a good avenue to precisely construct ultrahigh-density magnetic data storage devices.

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SDN中DDoS攻击检测与混合防御技术

现代电子技术 2025年第2期48卷 85-89页

作者：李小菲陈义河北大学信息技术中心河北保定071002 河北大学计算机教学部河北保定071001

DDoS攻击是软件定义网络(SDN)安全领域的一大威胁,严重威胁网络控制器及交换机等设备的正常运行,因此提出一种SDN中DDoS攻击检测与混合防御技术。在DDoS攻击检测方面,利用卡方检验值对SDN中控制器收到的Packet_In数据流内数据帧数量进... 详细信息

DDoS攻击是软件定义网络(SDN)安全领域的一大威胁,严重威胁网络控制器及交换机等设备的正常运行,因此提出一种SDN中DDoS攻击检测与混合防御技术。在DDoS攻击检测方面,利用卡方检验值对SDN中控制器收到的Packet_In数据流内数据帧数量进行统计分析,将高于数据流卡方阈值的数据流初步判断为可疑流;继续计算数据流与可疑流的相对Sibson距离,区分可疑流是DDoS攻击流还是正常突发流;最后通过计算数据流之间的Sibson距离,根据DDoS攻击流的特征,确定攻击流是否为DDoS攻击流。在DDoS攻击防御方面,采用共享流表空间支持和Packet_In报文过滤方法混合防御,被DDoS攻击的交换机流表空间过载,将过载流表引流到其他交换机,从而完成数据层的防御;溯源得到DDoS攻击MAC地址并进行Packet_In数据流过滤,完成控制层的防御。实验结果表明,所提方法可有效检测软件定义网络交换机和控制器内的DDoS攻击流,能够防御不同的DDoS攻击。

关键词：软件定义网络 DDoS攻击流攻击检测混合防御卡方检验值 Sibson距离流表空间共享

模因论教学法对大学英语低级别学生产出性词汇学习的影响

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肇庆学院学报 2025年第1期46卷 66-72页

作者：陈宜黄洪志福建医科大学文理艺术学院福建福州350122

本研究探讨了基于模因论的英语教学方法对大学英语低级别学生产出性词汇学习效果的影响。研究选取两个英语低级别班级作为实验对象,随机分为实验组(n=51)和对照组(n=51)。实验组接受基于模因论的词汇教学,而对照组则采用传统教学方法。... 详细信息

本研究探讨了基于模因论的英语教学方法对大学英语低级别学生产出性词汇学习效果的影响。研究选取两个英语低级别班级作为实验对象,随机分为实验组(n=51)和对照组(n=51)。实验组接受基于模因论的词汇教学,而对照组则采用传统教学方法。研究通过前测和两次后测收集数据,使用独立样本t检验分析每次测试中两组学生在产出性词汇掌握程度上的差异。结果显示,实验组在两次后测中的词汇学习成绩均显著优于对照组,表明基于模因论的教学方法能有效提高大学英语低级别学生的产出性词汇能力。本研究为英语词汇教学,特别是针对低级别学习者的教学策略提供了新的思路和实证依据,对提升学生的英语表达能力具有一定意义。

关键词：模因论大学英语低级别学生产出性词汇

The Willmore functional of surfaces

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Applied Mathematics(A Journal of Chinese Universities) 2013年第4期28卷 485-493页

作者： chen Jing-yi Department of Mathematics University of British ColumbiaVancouver B.C. V6T1Z2 Canada

The Whitney immersion theorem asserts that every smooth n-dimensional manifold can be immersed in R2n-1, in particular, smooth surfaces can be immersed in R3, and for embeddings the ambient dimension needs to go up by 1. Immersions or embeddings carry both intrinsic and extrinsic information of manifolds, and the latter determines how the manifold fits into the Euclidean space. The key geometric quantity to capture the extrinsic geometry is the second fundamental form.

关键词： Willmore functional Berstein type theorem W2,2 conformal immersions and compactness

Scattering Analysis and Optimization of Spherical Acoustic Cloak with Unideal Pentamode Material

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Acta Mechanica Solida Sinica 2020年第3期33卷 347-360页

作者： Xin Nie yi chen Xiaoning Liu Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationSchool of Aerospace EngineeringBeijing Institute of TechnologyBeijing 100081China

The acoustic scattering is theoretically studied in this paper for three-dimensional spherical cloak composed of unideal pentamode material,for which small shear rigidity is always inevitable for a real designed microstructure.A theoretical formulation is developed to efficiently evaluate the cloaking *** generic scattering feature of the cloak and the efTects of material imperfectness and inner cloak boundary constraints are systematically *** preferable constraint type and the critical imperfectness parameter of the material are identified for possible broadband *** addition,a very practical lining shell scheme is proposed to tune the constraint strength on the inner *** combining the theoretical model with optimization algorithm,it is further proved that the cloak can be reduced by several piecewiseuniform layers and optimized to achieve excellent invisibility in targeted frequency *** study will provide valuable guidance for the future microstructural design of cloaks.

关键词： Pentamode material Spherical acoustic cloak Scattering calculation Boundary effect Optimization

Hematite-facilitated microbial ammoxidation for enhanced nitrogen removal in constructed wetlands

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Frontiers of Environmental Science & Engineering 2024年第7期18卷 35-45页

作者： Hao Qin Wenbo Nie Duo yi Dongxu Yang Mengli chen Tao Liu yi chen Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment(Ministry of Education) Chongqing UniversityChongqing 400045China College of Environment and Ecology Chongqing UniversityChongqing 400045China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 610031China

Constructed wetlands(CWs)are widely applied for decentralized wastewater ***,achieving efficient removal of ammonia(NH+-N)has proven challenging due to insufficient *** this study,natural hematite(Fe,O3)was employed as a CW substrate(H-CWs)for the first time to drive anaerobic ammonia oxidation coupled with iron(I)reduction(Feammox).Compared to gravel constructed wetlands(G-CWs),ammonia removal was enhanced by 38.14%to 54.03%and nitrous oxide(N_(2)0)emissions were reduced by 34.60%in *** synergistic removal of ammonia and nitrate by H-CWs also resulted in the absence of ammoxidation *** and 15N isotope tracer incubations showed that Feammox accounting for approximately 40%of all ammonia removal in the *** enrichment of iron phosphate(Fe_(3)Fe_(4)(PO_(4))_(6))promoted the accumulation of the Feammox intermediate compound *** nanowires were observed on the surface of H-CW substrates as well,suggesting that the observed biological ammoxidation was most likely related to extracellular electron transfer(EET).Microbial and metagenomics analysis revealed that H-CWs elevated the integrity and enhanced the abundance of functional microorganisms and genes associated with nitrogen ***,the efficient ammonia removal in the absence of O2 together with a reduction in N_(2)O emissions as described in this study may provide useful guidance for hematite-mediated anaerobic ammonia removal in CWs.

关键词： Constructed wetlands Nitrogen removal Feammox Hematite Iron cycle

Collision Avoidance Strategy Supported by LTE-V-Based Vehicle Automation and Communication Systems for Car Following

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Tsinghua Science and Technology 2020年第1期25卷 127-139页

作者： Jiayang Li yi Zhang Mengkai Shi Qi Liu yi chen Department of Mathematics Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology(BNRist) Department of AutomationTsinghua UniversityBeijing 100084China Tsinghua-Berkeley Shenzhen Institute(TBSI) Shenzhen 518055China Jiangsu Province Collaborative Innovation Center of Modern Urban Traffic Technologies Nanjing 210096China Beijing Nebula Link Tech.Co.Ltd Beijing 100080China Network Technology Research Institute China UnicomBeijing 100044China

We analyzed and improved a collision avoidance strategy, which was supported by Long Term EvolutionVehicle(LTE-V)-based Vehicle-to-Vehicle(V2 V) communication, for automated vehicles. This work was completed in two steps. In the first step, we analyzed the probability distribution of message transmission time, which was conditional on transmission distance and vehicle density. Our analysis revealed that transmission time exhibited a near-linear increase with distance and density. We also quantified the trade-off between high/low resource reselection probabilities to improve the setting of media access parameters. In the second step, we studied the required safety distance in accordance with the response time, i.e., the transmission time, derived on the basis of a novel concept of Responsibility-Sensitive Safety(RSS). We improved the strategy by considering the uncertainty of response time and its dependence on vehicle distance and density. We performed theoretical analysis and numerical testing to illustrate the effectiveness of the improved robust RSS strategy. Our results enhance the practicability of building driverless highways with special lanes reserved for the exclusive use of LTE-V vehicles.

关键词： vehicle automation and communication collision avoidance Long Term Evolution-Vehicle(LTE-V) Responsibility-Sensitive Safety(RSS)

Visual Exploration of Differences Among DTI Fiber Models

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Chinese Journal of Electronics 2018年第5期27卷 959-967页

作者： MEI Honghui GUO Fangzhou chen Haidong chen yi chen Wei State Key Lab of CAD&CG Zhejiang University Beijing Key Laboratory of Big Data Technology for Food Safety Beijing Technology and Business University

In-vivo studies of fibrous structures require non-invasive tools, of which one is fiber tracking based on Diffusion tensor imaging(DTI) datasets. Different fiber models can be produced from different DTI images, which may vary from subject to subject due to variations in anatomy, motions in scanning, and signal noises. Additionally, parameters of the tracking method also have a great influence on resulting models. Illustrating, exploring, and analyzing differences among DTI fiber models are crucial for the purposes of group comparison,atlas construction, and uncertainty analysis. Conventional approaches illustrate fiber models in 3D space and explore differences either voxel-wisely or fiber-based. However, these approaches rely on accurate alignment processes and may easily be disturbed by visual clutters. We introduce a two-phase pro jection technique to illustrate a complex 3D fiber model with a unique 2D map to characterize features for further exploration and analysis. Moreover, regions of significant differences among the maps are marked out. In these 2D maps, differences can be easily distinguished without occlusions that often occur in 3D spaces. To facilitate comparative analysis from multiple perspectives, we design an interface for interactive exploration. The effectiveness of our approach is evaluated with two datasets.

关键词： Diffusion tensor imaging Fiber tracking Difference visualization Visual exploration

Poroelastic behaviors of the osteon: A comparison of two theoretical osteon models

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Acta Mechanica Sinica 2013年第4期29卷 612-621页

作者： Xiao-Gang Wu Wei-yi chen College of Mechanics Taiyuan University of Technology

In the paper, two theoretical poroelastic osteon models are presented to compare their poroelastic behaviors, one is the hollow osteon model （Haversian fluid is neglected） and the other is the osteon model with Haversian fluid con- sidered. They both have the same two types of imperme- able exterior boundary conditions, one is elastic restraint and the other is displacement constrained, which can be used for analyzing other experiments performed on similarly shaped poroelastic specimens. The obtained analytical pressure and velocity solutions demonstrate the effects of the loading fac- tors and the material parameters, which may have a signifi- cant stimulus to the mechanotransduction of bone remodel- ing signals. Model comparisons indicate：（1） The Haversian fluid can enhance the whole osteonal fluid pressure and ve- locity fields. （2） In the hollow model, the key loading fac- tor governing the poroelastic behavior of the osteon is strain rate, while in the model with Haversian fluid considered, the strain rate governs only the velocity. （3） The pressure ampli- tude is proportional to the loading frequency in the hollow model, while in the model with Haversian fluid considered, the loading frequency has little effect on the pressure ampli- tude.

关键词： Osteon ~ Poroelasticity ~ Haversian fluid - Porepressure ~ Annular cylinder