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香港中学文凭考试等级预测研究

中国考试 2024年第2期 33-39+101页

作者：许嘉凌萧伟乐席小明香港考试及评核局

为研究香港中学文凭考试（简称文凭试）等级预测结果，以过往文凭试结果作为依据，通过标准化程序，对2020—2023年共计146 180名考生根据其校内评核成绩进行文凭试等级预测；并采用问卷调查法，基于各参与学校组织架构、教师的工作经... 详细信息

为研究香港中学文凭考试（简称文凭试）等级预测结果，以过往文凭试结果作为依据，通过标准化程序，对2020—2023年共计146 180名考生根据其校内评核成绩进行文凭试等级预测；并采用问卷调查法，基于各参与学校组织架构、教师的工作经验、公开考试阅卷经验及专业发展活动等，运用多层线性模型探讨学校属性与校内评核的关系。结果显示：中文、英文、数学、通识教育4门核心科目等级预测结果具有较高的准确度，其中英文预测结果最佳，其余3科预测结果类似；选修科目则因每年选考人数少导致文凭试成绩变化大，进而影响预测结果；多层线性模型分析显示，不同学校属性对于不同科目的校内评核具有不同的预测效果。

关键词：香港中学文凭考试等级预测校内评核标准参照测验

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香港地区中学文凭考试等级预测研究

中国考试 2024年第2期 33-39,101页

作者：许嘉凌萧伟乐席小明香港考试及评核局中国香港999077

为研究香港地区中学文凭考试(简称文凭试)等级预测结果,以过往文凭试结果作为依据,通过标准化程序,对2020—2023年共计146180名考生根据其校内评核成绩进行文凭试等级预测;并采用问卷调查法,基于各参与学校组织架构、教师的工作经验、... 详细信息

为研究香港地区中学文凭考试(简称文凭试)等级预测结果,以过往文凭试结果作为依据,通过标准化程序,对2020—2023年共计146180名考生根据其校内评核成绩进行文凭试等级预测;并采用问卷调查法,基于各参与学校组织架构、教师的工作经验、公开考试阅卷经验及专业发展活动等,运用多层线性模型探讨学校属性与校内评核的关系。结果显示:中文、英文、数学、通识教育4门核心科目等级预测结果具有较高的准确度,其中英文预测结果最佳,其余3科预测结果类似;选修科目则因每年选考人数少导致文凭试成绩变化大,进而影响预测结果;多层线性模型分析显示,不同学校属性对于不同科目的校内评核具有不同的预测效果。

关键词：香港地区中学文凭考试等级预测校内评核标准参照测验

高功率光纤激光器反常模式不稳定效应实验研究

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中国激光 2024年第6期51卷 1-8页

作者：曾令筏文榆钧王小林王鹏奚小明杨保来张汉伟习锋杰韩凯王泽锋许晓军国防科技大学前沿交叉学科学院湖南长沙410073 国防科技大学南湖之光实验室湖南长沙410073 国防科技大学高能激光技术湖南省重点实验室湖南长沙410073

模式不稳定是限制当前高功率光纤激光器功率提升的主要因素。在近单模光纤激光器中,一般采用减小光纤弯曲直径的方法增加高阶模损耗、提升模式不稳定阈值;然而,少模光纤激光器中存在多个高阶模式,会导致动态模式不稳定(TMI)阈值随着弯... 详细信息

模式不稳定是限制当前高功率光纤激光器功率提升的主要因素。在近单模光纤激光器中,一般采用减小光纤弯曲直径的方法增加高阶模损耗、提升模式不稳定阈值;然而,少模光纤激光器中存在多个高阶模式,会导致动态模式不稳定(TMI)阈值随着弯曲直径减小而降低的反常模式不稳定现象。基于纤芯/包层直径为30/600μm的双包层掺镱光纤以及具有不同直径的光纤水冷柱,设计了一台后向泵浦的高功率光纤放大器,研究了该激光器中的反常模式不稳定现象。结果表明:当采用中心波长为976 nm的稳波长激光二极管(LD)作为泵浦源时,随着增益光纤弯曲直径由13 cm增加至16 cm,激光器的TMI阈值由1650 W提升至3740 W,提升幅度约为1.27倍,输出激光的相对亮度提升了87%。光纤弯曲直径的增加虽然会带来输出激光光束质量的轻微退化,但输出激光的相对亮度能够大幅提升。最终,结合光纤弯曲以及泵浦波长优化,实现了7.1 kW高亮度光纤激光输出,相对亮度为1293。

关键词：光纤光学光纤放大器反常模式不稳定光纤弯曲泵浦波长优化

香港地区中学文凭考试诊断反馈系统的开发及改进

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中国考试 2024年第2期 40-46页

作者：禤美瑶萧伟乐周钜宽杨汉基席小明香港考试及评核局中国香港999077

为进一步推动“评核促进学习”,香港地区考试及评核局以历年香港地区中学文凭考试(HKDSE)的评核数据为基础开发了HKDSE诊断反馈系统。目前,该系统结合HKDSE 6个科目选择题的试题库,对学生学习表现数据加以分析并建立统计模型,为教师与... 详细信息

为进一步推动“评核促进学习”,香港地区考试及评核局以历年香港地区中学文凭考试(HKDSE)的评核数据为基础开发了HKDSE诊断反馈系统。目前,该系统结合HKDSE 6个科目选择题的试题库,对学生学习表现数据加以分析并建立统计模型,为教师与学生提供诊断性反馈报告,突出学生在不同能力或范畴的不足与强项。来自14所学校的约2200名学生及教师试用了该系统,通过问卷调查和访谈法,收集意见建议,以改进系统设计。系统改良版在“数据主导评核提升计划”中正式推出,辅之以学科教师培训,以帮助学校提升评核质量。

关键词：香港地区中学文凭考试诊断反馈评核促进学习个性化学习

Difficulty-aware prior-guided hierarchical network for adaptive segmentation of breast tumors

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Science China(Information Sciences) 2023年第2期66卷 127-141页

作者： Sumaira HUSSAIN xiaoming xi Inam ULLAH Syeda Wajiha NAIM Kashif SHAHEED Cuihuan TIAN Yilong YIN School of Software Engineering Shandong University Department of Computer Science Sindh Madressatul Islam University School of Computer Science and Technology Shandong Jianzhu University School of Computer Science and Engineering South China University of Technology School of Medicine Shandong University Health Management Center Qilu Hospital of Shandong University

Breast tumor segmentation is vital to tumor detection at the early stages. Deep learning methods are typically used in automatic tumor segmentation tasks. However, in existing methods, the difference between pixels is disregarded, and the union network architecture is used to segment all pixels; these methods involve a tradeoff between accuracy and efficiency. A novel, difficulty-aware, prior-guided hierarchical network for the adaptive segmentation of breast tumors is presented herein. A difficulty prior learning module is proposed to learn the pixel’s difficulty prior to guild adaptive segmentation in the proposed network. To achieve a more accurate segmentation of hard pixels, a hard pixel processing unit is presented to learn more discriminative features for hard pixels. Experiments are conducted based on three datasets. The experimental results show that the proposed methods outperform traditional deep learning methods and achieve a balance between accuracy and efficiency.

关键词： breast tumor ultrasound image segmentation deep neural network difficulty-awareness

Structural self-reconstruction strategy empowering Ni-rich layered cathodes with low-strain for superior cyclabilities

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Nano Research 2023年第4期16卷 4950-4960页

作者： Zhouliang Tan Yunjiao Li xiaoming xi Shijie Jiang xiaohui Li xingjie Shen Panpan Zhang Zhenjiang He School of Metallurgy and Environment Central South UniversityChangsha 410083China Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083China Changsha Research Institute of Mining and Metallurgy Changsha 410083China Office of Laboratory and Equipment Management Xinjiang UniversityUrumqi 830000China

The key to hindering the commercial application of Ni-rich layered cathode is its severe structural and interface degradation during the undesired phase transition(hexagonal to hexagonal(H2→H3)),degenerating from the build-up of mechanical strain and undesired parasitic ***,a perovskite Li_(0.35)La_(0.55)TiO_(3)(LLTO)layer is built onto Ni-rich cathodes crystal to induce layered@spinel@perovskite heterostructure to solve the root cause of capacity *** exploration based on structure characterizations,in situ X-ray diffraction techniques,and first-principles calculations demonstrate that such a unique heterostructure not only can improve the ability of the host structure to withstand the mechanical strain but also provides fast diffusion channels for lithium ions as well as provides a protective barrier against electrolyte ***,the LLTO modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)cathode manifests an unexpected cyclability with an extremely high-capacity retention of≈94.6%after 100 cycles,which is superior to the pristine LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(79.8%).Furthermore,this modified electrode also shows significantly enhanced cycling stability even withstanding a high cut-off voltage of 4.6 *** surface self-reconstruction strategy provides deep insight into the structure/interface engineering to synergistically stabilize structure stability and regulate the physicochemical properties of Ni-rich cathodes,which will also unlock a new perspective of surface interface engineering for layered cathode materials.

关键词： Ni-rich layered oxides cathode structural self-reconstruction phase transition mechanical strain first-principal calculation

External-to-internal synergistic strategy to enable multi-scale stabilization of LiCoO_(2)at high-voltage

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Journal of Energy Chemistry 2023年第1期76卷 516-527,I0013页

作者： Shuaipeng Hao Yunjiao Li Jiachao Yang Shan Wang Zhouliang Tan xiaoming xi Zhenjiang He Panpan Zhang School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina Changsha Research Institute of Mining and Metallurgy Changsha 410083HunanChina Office of Laboratory and Equipment Management Xinjiang UniversityUrumqi 830000XinjiangChina

High-voltage LiCoO_(2)(LCO)offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries,however,LiCoO_(2)is subject to serious structural and interfacial degradation above voltages>4.55 V(***/Li^(+)).Herein,an in-situ Li_(6.25)La_(3)Zr_(2)A_(l0.25)O_(12)(LLZAO)layer is constructed on the LCO surface to achieve operating voltage at 4.6 *** detailed characterizations(ex-situ XRD,ex-situ Raman,DFT,etc.)reveal that the LLZAO layer greatly enhances Li+conductivity attributed to the ionconducting layer on the surface/interface,and closely combines with LiCoO_(2)particle to ensure stable cathode/electrolyte interface,thus suppressing the highly reactive Co^(4+)and O^(-)triggered surface side reactions at ***,the introduction of La^(3+)/Zr^(4+)/Al^(3+)with a larger ionic radius(La^(3+)/Zr^(4+)are larger than Co^(3+))and weaker electronegativity(La/Zr/Al are weaker than Co)into Co^(3+)sites readjusts the electron cloud density between Co–O–Li,which reinforces the Co–O bond and widens the band-center gap of Co 3d and O 2p,thus restraining the detrimental phase transition(from H3 to H1-3 phase)and the formation of Co_(3)O_(4)spinel phase(attributed to lattice oxygen release),subsequently alleviating the particle cracking and structural collapse during repeated Li^(+)de/***,after 100 cycles at 3.0–4.6 V,LCO@1.0LLZAO exhibits a superior discharge capacity of 188.5 m A h g^(-1),with a capacity retention of 85.1%.The above research has brought about meaningful guidance for the evolution of cathode materials with high voltage.

关键词： LLZAO layer High-voltage LiCoO_(2) Irreversible phase transition Band-center gap Lattice oxygen release

A novelty strategy induced pinning effect and defect structure in Ni-rich layered cathodes towards boosting its electrochemical performance

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Journal of Energy Chemistry 2022年第9期31卷 570-580,I0016页

作者： Zhouliang Tan Yunjiao Li xiaoming xi Shijie Jiang xiaohui Li xingjie Shen Panpan Zhang Zhenjiang He Junchao Zheng School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina Changsha Research Institute of Mining and Metallurgy Changsha 410083HunanChina Office of Laboratory and Equipment Management Xinjiang UniversityUrumqi 830000XinjiangChina

Layered Ni-rich transition metal oxide is treated as the most promising alternative cathode due to their high-capacity and flexible ***,the severe lattice strain and slow Li-ion migration kinetics severely restrict their practical ***,a novelty strategy induced pinning effect and defect structure in layered Ni-rich transition metal oxide cathodes is proposed via a facile cation(iron ion)/anion(polyanion)co-doping ***,the effects of pinning effect and defect structure on element valence state,crystal structure,morphology,lattice strain,and electrochemical performance during lithiation/delithiation are systematically *** detailed characterizations(soft X-ray absorption spectroscopy(sXAS),in-situ X-ray diffraction(XRD),etc.)and density functional theory(DFT)calculation demonstrate that the pinning effects built-in LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)materials by the dual-site occupation of iron ions on lithium and transition metal sites effectively alleviate the abrupt lattice strain caused by an unfavorable phase transition and the subsequent induction of defect structures in the Li layer can greatly reduce the lithium-ion diffusion ***,the modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)exhibits a high-capacity of 206.5 mAh g^(-1)and remarkably enhanced capacity retention of 93.9%after 100 cycles,far superior to~14.1%of the pristine ***,an excellent discharge capacity of 180.1 mAh g^(-1)at 10 C rate is maintained,illustrating its remarkable rate *** work reports a pinning effect and defect engineering method to suppress the lattice strain and alleviate lithium-ion kinetic barriers in the Ni-rich layered cathodes,providing a roadmap for understanding the fundamental mechanism of an intrinsic activity modulation and structural design of layered cathode materials.

关键词： Ni-rich layered cathode Pinning effect Defect structure Lattice strain Lithium-ion kinetic

Designing and evaluating assessment and learning in adaptive learning systems

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语言测试与评价 2022年第1期 94-115,119,120页

作者： xi xiaoming Hong Kong Examinations and Assessment Authority

The recent emergence of adaptive language learning systems calls for conceptual work to guide the design of assessment and learning in an adaptive *** adaptive learning might have been touted as a universal cure for learning problems,many adaptive language learning systems fall short of educators’expectations,partly due to a lack of standards and best practices in this *** fill this gap,this paper proposes some major considerations in designing a high-quality assessment and learning experience in adaptive learning and ways to evaluate an adaptive learning *** architecture of adaptive learning is decomposed,with a chain of inferences supporting the overall efficacy of an adaptive learning system presented,including user property representation,user property estimation,content representation,user interaction representation,and user interaction impact.A detailed analysis of key validity issues is provided for each inference,which motivates the major considerations in designing and evaluating assessment and *** paper first provides an overview of different types of assessment used in adaptive learning and an analysis of the assessment approach,priorities,and design considerations of each to optimize its use in adaptive *** it proposes a framework for evaluating different aspects of an adaptive learning *** special connections are made to models,techniques,designs,and technologies specific to language learning and assessment,bringing more relevance to adaptive language learning *** establishing some guidelines on key aspects to evaluate and how to evaluate them,the work intends to bring more rigor to the field of adaptive language learning systems.

关键词： assessment adaptive learning evaluation framework efficacy validity