检索结果-南通市图书馆

面向广电5G的NTN融合组网架构与关键技术研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

广播与电视技术 2024年第10期51卷 46-50页

作者：梁海凤王志峰庞硕中广电广播电影电视设计研究院有限公司北京100045

本文概述了5G非地面网络(NTN)的背景及发展现状,从3GPP标准演进、网络架构以及国内运营商的研究进展三个方面详细介绍了5G NTN的技术特点。提出了面向5G-Advanced时代的NTN融合组网架构,深入分析了其中的关键技术,并探讨了广电5G+NTN融... 详细信息

本文概述了5G非地面网络(NTN)的背景及发展现状,从3GPP标准演进、网络架构以及国内运营商的研究进展三个方面详细介绍了5G NTN的技术特点。提出了面向5G-Advanced时代的NTN融合组网架构,深入分析了其中的关键技术,并探讨了广电5G+NTN融合组网在实际应用中的潜在场景。

关键词：广电5G NTN 5G-A 星地融合

熔盐塔式太阳能吸热器传热特性计算模型研究进展

在线全文

学校读者我要写书评

暂无评论

热力发电 2024年第7期53卷 24-33页

作者：唐宪友张亚南李欣怡白凤武王志峰中国广核新能源控股有限公司北京100160 中国科学院电工研究所北京100190 中国科学院大学北京100190

熔盐塔式太阳能热发电技术是目前国际主流的光热发电技术,熔盐吸热器作为将太阳能转换为热能的核心设备,其性能直接影响系统发电效率,吸热器安全性影响电厂运行小时数。因此,建立熔盐吸热器传热模型,获得准确的传热特性十分重要。对主... 详细信息

熔盐塔式太阳能热发电技术是目前国际主流的光热发电技术,熔盐吸热器作为将太阳能转换为热能的核心设备,其性能直接影响系统发电效率,吸热器安全性影响电厂运行小时数。因此,建立熔盐吸热器传热模型,获得准确的传热特性十分重要。对主流的外置圆柱式熔盐吸热器的传热计算模型进行了系统梳理,总结了传热模型中投入辐射能、辐射热损失、对流热损失及熔盐得热量的计算过程及基本方法。根据计算结果的精细程度,吸热器传热模型分为详细模型和简化模型。详细模型的计算精度高,能细致反映实际能量转换过程,但计算成本较高,瞬态过程计算耗时多,但其特定工况的计算结果可为简化模型提供计算结果的验证参考。简化模型是对描述熔盐吸热器传热特性的理论模型做合理简化,在较为准确地完成计算的同时具备较快的计算速度,多用于吸热器设计阶段。通过各模型特点及性能的总结对比,可为熔盐吸热器热性能计算过程的传热模型选择提供技术指导。

关键词：熔盐塔式太阳能热发电技术外置圆柱式吸热器计算模型热性能参数

The Multireceiver Commitment Schemes

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2008年第6期13卷 759-764页

作者： wang Shuhong QI zhifeng Security Research Center Sumavision Technologies CO. LTD. Beijing 100085 China

Existing commitment schemes were addressed under the classic two-party scenario, However, popularity of the secure multi-party computation in today＇s lush network communication is motivating us to adopt more sophisticate commitment schemes. In this paper, we study for the first time multireceiver commitment in unconditionally secure setting, i.e., one committer promises a group of verifiers a common secret value （in computational setting it is trivial）. We extend the Rivest model for this purpose and present a provably secure generic construction using multireceiver authentication codes （without secrecy） as building blocks. Two concrete schemes are proposed as its immediate implementations, which are almost as efficient as an optimal MRA-code. We believe using other primitives to construct variants of this concept will open doors for more interesting research.

关键词： commitment scheme multi-party computation unconditional security authentication code verifiable secret sharing

Measurement of the remnant magnetic-field in Lorentz mode using permalloy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2009年第6期22卷 435-439页

作者： Haihua LIU Xiaokun DUAN Renchao CHE zhifeng wang Xiaofeng DUAN Beijing Laboratory of Electron Microscopy Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics Chinese Academy of Sciences Beijing 100190 China Advanced Technology ＆ Materials Co. Ltd. Beijing 100081 China

A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-tie wall in Permalloy is used to measure the remnant magnetic field by tilting the specimen and adjusting the objective lens current. The remnant magnetic field is estimated to be about 17 Oe, in a direction opposite to that of the objective lens magnetic field. The remnant magnetic field can be compensated by adjusting the value of the objective lens current.

关键词： Lorentz electron microscopy Lorentz lens Remnant magneticfield Permalloy Cross-tie walls

Estimation and Prediction of Typhoons and Wave Overtopping in Qingdao, China

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2020年第5期19卷 1017-1028页

作者： wang zhifeng LI Songtao HAO Yan MA Yan WU Kejian Shandong Province Key Laboratory of Ocean Engineering Ocean University of ChinaQingdao 266100China Qingdao Meteorological Bureau Qingdao 266003China College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China

This study aims to estimate and predict the impact of climate change on typhoons and wave overtopping during typhoon progresses in Qingdao, China. The SWAN wave model is used to simulate wave elements. The scale coefficients of wave overtopping are estimated using an empirical prediction formula. A total of 75 tropical cyclones affected Qingdao from 1949 to 2019. These tropical cyclones can be grouped into eight categories according to typhoon tracks. Typhoon wind speed during Track G is projected to decrease, and those of the other seven typhoon progresses will increase by 0.35% – 0.75% in 2025, 0.69% – 1.5% in 2035, and 1.38% – 3.0% in 2055. The significant wave height and wave overtopping outside the bay are greater than those inside the bay. Among the 506 typical points selected, the maximum values of the significant wave height and wave overtopping inside the bay are mainly distributed in the range of 0 – 2 m and 0 – 60 m^3 km^(-1) s^(-1), respectively. The increments of the significant wave height and wave overtopping of Track F are most obvious. The significant wave height of Track F will increase by 50.5% in 2025, 51.8% in 2035, and 53.4% in 2055. In the 2℃ scenario, the maximum value of wave overtopping of Track F will increase by 21.9% in 2025, 24.3% in 2035, and 29.5% in 2055. In the 4℃ scenario, the maximum value of wave overtopping of Track F will increase by 21.9% in 2025, 24.3% in 2035, and 29.5% in 2055.

关键词： climate change typhoon wind typhoon wave wave overtopping Qingdao

A numerical estimation of the impact of Stokes drift on upper ocean temperature

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2014年第7期33卷 48-55页

作者： ZHANG Xiaoshuang wang zhifeng wang Bin WU Kejian HAN Guijun LI Wei Key Laboratory of Marine Environmental Information Technology National Marine Data and Information ServiceState Oceanic Administration Ocean University of China National Ocean Technology Center State Oceanic Administration

The impact of Stokes drift on the mixed layer temperature variation was estimated by taking into account an advective heat transport term induced by the Stokes drift in the equation of mixed layer temperature and using the oceanic and wave parameters from a global ocean circulation model （HYCOM） and a wave model （Wave Watch III）. The dimensional analysis and quantitative estimation method were conducted to assess the importance of the effect induced by the Stokes drift and to analyze its spatial distribution and seasonal variation characteristics. Results show that the contribution of the Stokes drift to the mixed layer temperature variation at mid-to-high latitudes is comparable with that of the mean current, and a substantial part of mixed layer temperature change is induced by taking the Stokes drift effect into account. Although the advection heat transport induced by the Stokes drift is not the leading term for the mixed layer temperature equation, it cannot be neglected and even becomes critical in some regions for the simulation of the upperocean temperature.

关键词： sea surface waves Stokes drift mixed layer temperature

中低位直肠癌新辅助放疗前后肛门功能的比较:单中心回顾性观察性研究

在线全文

学校读者我要写书评

暂无评论

中华胃肠外科杂志 2024年第1期27卷 63-68页

作者：孙振王智凤孙曦羽徐徕张冠南陆君阳肖毅中国医学科学院北京协和医学院、北京协和医院基本外科结直肠专业组北京100730 中国医学科学院北京协和医学院、北京协和医院消化内科北京100730

目的比较中低位直肠癌患者放疗前后的肛门测压资料,探讨新辅助放疗对肛门功能的影响。方法本研究采用回顾性观察性研究方法,收集2020年6月至2023年4月期间,北京协和医院基本外科结直肠专业组直肠癌前瞻性登记数据库中具有新辅助放疗前... 详细信息

目的比较中低位直肠癌患者放疗前后的肛门测压资料,探讨新辅助放疗对肛门功能的影响。方法本研究采用回顾性观察性研究方法,收集2020年6月至2023年4月期间,北京协和医院基本外科结直肠专业组直肠癌前瞻性登记数据库中具有新辅助放疗前后肛门直肠压力测定数据的中低位直肠癌患者临床资料,观察指标包括患者临床病理资料以及新辅助放疗前后患者肛门直肠压力测定结果,并使用logistic回归分析确定与肛门直肠测压指标发生显著改变的有关因素。结果对45例中低位直肠癌患者进行分析。其中男性32例(71.1%),女性13例(28.9%);年龄为(60±11)岁;体质指数(BMI)为(23.4±3.7)kg/m^(2)。肿瘤距肛缘距离为(5.4±1.5)cm,MRI T分期(mrT)3~4期患者有41例(81.1%),MRI N分期(mrN)阳性患者有40例(88.9%),肿瘤最大径中位数为3.4(2.9~4.5)cm,环周比中位数为66.0(45.5~75.0)%。新辅助放疗后患者的最大静息压有降低的趋势[(55.3±32.0)mmHg比(48.0±28.5)mmHg,t=1.930,P=0.060],但差异无统计学意义;最大缩榨压无明显变化。新辅助放疗后患者各时期感觉阈值均降低,其中感觉阈值的最大耐受量降低具有统计学意义[66.0(49.0,88.0)ml比52.0(39.0,73.5)ml,Z=-2.481,P=0.013]。logistic回归分析结果提示,mrN降期与最大静息压的降低有关(OR=6.533,95%CI:1.254~34.051,P=0.026),未发现与感觉阈值的最大耐受量降低有关的因素。结论新辅助放疗会导致直肠癌患者肛门功能损伤,使得肛门静息压降低和排便敏感性增高,此外mrN降期与最大静息压的降低有关。

关键词：直肠肿瘤新辅助放疗肛门功能肛门直肠测压

在线全文

学校读者我要写书评

暂无评论

可视化反馈促进自我调节学习的实验研究

中国教育信息化 2024年第2期30卷 119-128页

作者：罗恒李洁张雪迪王志锋华中师范大学人工智能教育学部湖北武汉430070 华南师范大学附属中学增城学校广东广州511300

建设终身学习型社会要求学习者具备更高的自我调节学习能力。这就要求教育不仅要教会学生知识,更要教会学生学习。然而,当前关于促进基础教育中学习者自我调节学习的研究较少,并且缺乏可以应用于线下课堂的实用工具,导致测评数据无法被... 详细信息

建设终身学习型社会要求学习者具备更高的自我调节学习能力。这就要求教育不仅要教会学生知识,更要教会学生学习。然而,当前关于促进基础教育中学习者自我调节学习的研究较少,并且缺乏可以应用于线下课堂的实用工具,导致测评数据无法被深入解读。立足于基础教育课堂教学,设计开发促进学习者自我调节学习的可视化反馈工具,深入分析测评数据,挖掘其中蕴藏的有效信息。该工具提供包括自我认识、学习动机、学习策略三个维度的可视化反馈报告,将知识掌握情况、错题归因、试题定位等信息呈现给学习者,助力其自我调节学习的发生。为检验该工具的效果,在两个班级开展对比实验,对两组学生的自我调节学习能力和学习成绩进行差异性检验。独立样本T检验结果显示,实验班和对照班在自我调节学习能力和学习成绩之间均存在显著性差异,并且均呈现出0.4左右的效应量。证明该工具提供的可视化反馈报告能够有效促进学习者的自我调节学习,同时能够促进学业表现。

关键词：自我调节学习可视化学习反馈测评数据终身学习

Fabrication of quaternary Mg-Zn-Y-Ce quasi-crystal alloys and their strengthening effects on AZ91 magnesium alloys

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

China Foundry 2010年第4期7卷 342-348页

作者： wang zhifeng Zhao Weimin Li Haipeng Liang Chunyong School of Materials Science and Engineering Hebei University of Technology Tianjin 300130 China

Quaternary Mg-Zn-Y-Ce quasi-crystal-containing alloys were fabricated using a metal mold casting route. The microstructures of Mg-Zn-Y-Ce alloys and the distribution of the major elements were analyzed. The differences in morphology and micro-hardness between quaternary Mg-Zn-Y-Ce quasi-crystals and ternary Mg- Zn-Y quasi-crystals were discussed. The result showed that the micro-hardness of Mg-Zn-Y-Ce quasi-crystals reached peak value when the content of Ce was 0.8at.%. Subsequently, various contents of Mg-Zn-Y-0.8Ce alloys were used to strengthen AZ91 magnesium alloys. The microstructural modification and mechanical properties of reinforced AZ91 alloys with and without solution, as well as their aging treatments, were also studied. Further research showed that aging-treated AZ91-10wt.%(Mg-Zn-Y-0.8at.%Ce) alloys exhibited excellent mechanical properties: their Brinell hardness, tensile strength, and elongation were HV91, 252 MPa, and 4.1%, respectively. Through this study, the range of application of AZ91 alloys can further be extended.

关键词： quasi-crystals magnesium alloys AZ91 strengthening effects Mg-Zn-Y-Ce