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中美小学数学教材的比较研究——以三年级“分数的认识”为例

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数学教育学报 2016年第3期25卷 20-28页

作者：丁锐 yan ping xin 东北师范大学教育学部吉林长春130024 美国普渡大学教育学院西拉法叶47907

对比美国的en Vision math（简称EVM）和中国人教版两个版本的三年级小学数学教材中有关＂分数的认识＂部分（主要包括分数的引入、分数的意义、分数的大小比较等）的编写依据、主题、内容设计、组织结构和核心概念及规律的呈现方式等.... 详细信息

对比美国的en Vision math（简称EVM）和中国人教版两个版本的三年级小学数学教材中有关＂分数的认识＂部分（主要包括分数的引入、分数的意义、分数的大小比较等）的编写依据、主题、内容设计、组织结构和核心概念及规律的呈现方式等.结果发现,美国的EVM教材在三年级＂分数的认识＂部分强调不同的分数模型,比较忽视对分母、分子意义的理解;重视概念和规律的严谨性/完整性,但较少鼓励学生探究;同时,该教材注重不同的表征和方法,但是内容之间缺少较为紧密的联系.相比较来说,人教版数学教材在＂分数的初步认识＂部分则更强调学生对分数的基本意义（整体、分子、分母）的理解,而不是不同模型的介绍;强调通过直观和操作帮助学生建立分数的概念,进行大小比较;鼓励学生对规律进行探索和总结,重视计算和运算规律;内容设计由浅入深、逻辑联系紧密.

关键词：教材比较小学数学分数的意义分数模型

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我国航运业绿色低碳发展的需求、路径与展望

船海工程 2024年第4期53卷 1-5,12页

作者：范爱龙严新平李忠奎张海颖水路交通控制全国重点实验室(武汉理工大学) 武汉430063 武汉理工大学交通与物流工程学院武汉430063 交通运输部科学研究院北京100029

为探讨航运业在综合运输体系中的重要性,并针对加速航运业绿色低碳发展对实现交通运输行业双碳战略目标的意义展开分析。通过考察航运业当前的碳排放状况,分析我国在绿色低碳发展方面存在的问题,对国内外绿色航运政策需求及其对航运业... 详细信息

为探讨航运业在综合运输体系中的重要性,并针对加速航运业绿色低碳发展对实现交通运输行业双碳战略目标的意义展开分析。通过考察航运业当前的碳排放状况,分析我国在绿色低碳发展方面存在的问题,对国内外绿色航运政策需求及其对航运业的影响进行综合评估。在此基础上,研究我国航运业绿色低碳发展的路径,包括总体思路、基本原则,以及相应的策略与实施措施,展望航运业绿色低碳发展的技术创新方向,提出从能源替代和运营管理两个方面促进航运业绿色低碳发展。

关键词：航运业绿色低碳能源替代能效提升

斜航工况下吊舱推进器水动力性能数值及试验研究

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舰船科学技术 2024年第1期46卷 42-47页

作者：董小伟周永健张聪欧阳武梁兴鑫严新平招商局邮轮制造有限公司江苏南通226116 武汉理工大学船海与能源动力工程学院湖北武汉430063 武汉理工大学交通与物流工程学院湖北武汉430063 国家水运安全工程技术研究中心湖北武汉430063

为了探讨吊舱推进器在斜航工况下的水动力性能变化,以某豪华邮轮吊舱推进器为研究对象,采用STAR CCM+软件基于RANS(Reynolds-averaged Navier-Stokes)方法并结合标准速系数和偏转角的水动力性能进行数值模拟。同时,利用拖曳水池和吊舱... 详细信息

为了探讨吊舱推进器在斜航工况下的水动力性能变化,以某豪华邮轮吊舱推进器为研究对象,采用STAR CCM+软件基于RANS(Reynolds-averaged Navier-Stokes)方法并结合标准速系数和偏转角的水动力性能进行数值模拟。同时,利用拖曳水池和吊舱动力仪进行试验研究,并与仿真数据进行比较分析,进一步讨论螺旋桨与吊舱之间的相互作用对水动力性能的影响。结果表明,本文采用的数值模拟方法可较准确预测斜航工况下的水动力性能。螺旋桨推力系数、扭矩系数关于直航工况点对称,其数值随着偏转角的增大而增大;吊舱单元推力系数随着偏转角的增大而减小,吊舱侧向力随着偏转角的增大而增大;螺旋桨单元流场压力和流速在叶梢处达到最大值,吊舱左侧比右侧承担更多的表面压力幅值。

关键词：吊舱推进器偏转角度数值模拟模型试验水动力性能

Retinoic acid alleviates rotavirus-induced intestinal damage by regulating redox homeostasis and autophagic flux in piglets

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Animal Nutrition 2024年第1期16卷 409-421页

作者： xin Lai Aimin Wu Bing Yu Hui yan Junqiu Luo ping Zheng Jie Yu Daiwen Chen Institute of Animal Nutrition Sichuan Agricultural University Key Laboratory for Animal Disease-resistance Nutrition of China Ministry of Education Sichuan Agricultural University

Rotaviruses(RV) are a major cause of severe gastroenteritis, particularly in neonatal piglets. Despite the availability of effective vaccines, the development of antiviral therapies for RV remains an ongoing challenge. Retinoic acid(RA), a metabolite of vitamin A, has been shown to have anti-oxidative and antiviral properties. However, the mechanism by which RA exerts its intestinal-protective and antiviral effects on RV infection is not fully understood. The study investigates the effects of RA supplementation in Duroc × Landrace × Yorkshire(DLY) piglets challenged with RV. Thirty-six DLY piglets were assigned into six treatments, including a control group, RA treatment group with two concentration gradients(5and 15 mg/d), RV treatment group, and RV treatment group with the addition of different concentration gradients of RA(5 and 15 mg/d). Our study revealed that RV infection led to extensive intestinal architecture damage, which was mitigated by RA treatment at lower concentrations by increasing the villus height and villus height/crypt depth ratio(P < 0.05), enhancing intestinal stem cell signaling and promoting intestinal barrier functions. In addition, 15 mg/d RA supplementation significantly increased NRF2 and HO-1 protein expression(P < 0.05) and GSH content(P < 0.05), indicating that RA supplementation can enhance anti-oxidative signaling and redox homeostasis after RV challenge. Additionally,the research demonstrated that RA exerts a dual impact on the regulation of autophagy, both stimulating the initiation of autophagy and hindering the flow of autophagic flux. Through the modulation of autophagic flux, RA influence the progression of RV infection. These findings provide new insights into the regulation of redox hemostasis and autophagy by RA and its potential therapeutic application in RV infection.

关键词： Rotavirus Piglet Retinoic acid Intestinal barrier Redox hemostasis Autophagic flux

Latest insights into the global epidemiological features,screening,early diagnosis and prognosis prediction of esophageal squamous cell carcinoma

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World Journal of Gastroenterology 2024年第20期30卷 2638-2656页

作者： Yi-xin Zhao He-ping Zhao Meng-Yao Zhao yan Yu Xi Qi Ji-Han Wang Jing Lv Department of Clinical Laboratory Honghui HospitalXi’an Jiaotong UniversityXi’an 710054Shaanxi ProvinceChina Institute of Medical Research Northwestern Polytechnical UniversityXi’an 710072Shaanxi ProvinceChina

As a highly invasive carcinoma,esophageal cancer(EC)was the eighth most prevalent malignancy and the sixth leading cause of cancer-related death worldwide in 2020.Esophageal squamous cell carcinoma(ESCC)is the major histological subtype of EC,and its incidence and mortality rates are decreasing globally.Due to the lack of specific early symptoms,ESCC patients are usually diagnosed with advanced-stage disease with a poor prognosis,and the incidence and mortality rates are still high in many countries,especially in China.Therefore,enormous challenges still exist in the management of ESCC,and novel strategies are urgently needed to further decrease the incidence and mortality rates of ESCC.Although the key molecular mechanisms underlying ESCC pathogenesis have not been fully elucidated,certain promising biomarkers are being investigated to facilitate clinical decision-making.With the advent and advancement of highthroughput technologies,such as genomics,proteomics and metabolomics,valuable biomarkers with high sensitivity,specificity and stability could be identified for ESCC.Herein,we aimed to determine the epidemiological features of ESCC in different regions of the world,especially in China,and focused on novel molecular biomarkers associated with ESCC screening,early diagnosis and prognosis prediction.

关键词： Esophageal squamous cell carcinoma Epidemiology Diagnosis Genomics Proteomics Metabolomics

Study on tungsten sintering temperature field based on electromagnetic simulation and computational fluid dynamics

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Tungsten 2024年第2期6卷 355-366页

作者： Lu-yan Wang Yue-Guang Yu Jian-xin Dong Kai-ping Du Shan-Yu Liu Cao-Bing Li University of Science and Technology Beijing Beijing 100083China BGRIMM Technology Group Beijing 100160China China Iron&Steel Research Institute Group Beijing 100081China

In order to study the influence of various sintering variables more intuitively and clearly,electromagnetic field analysis and computational fl uid dynamics are used to analyze the infl uence of gas flow,heating power and other process parameters on the temperature range of medium-frequency sintering in this paper.The results indicate that the uniformity of temperature fi eld is determined by the gas flow rate and heating power.When the heating power is 50 kW,the stable temperature drops about 10 K for every 1 m^(3)·h^(−1)increase of hydrogen flow.The peak value of the maximum temperature diff erence on the tungsten rods gradually increases with the increase of the hydrogen flow rate,and it appears slightly later.The temperature distribution of tungsten rods in furnace is similar with diff erent hydrogen flow rate.At the same time,the closer to the furnace wall,the higher the temperature of the tungsten rod.The temperature diff erence between tungsten rods mainly occurred within 1 h after the beginning of heating.Increasing the heating power can improve the stable temperature,but has little eff ect on the heating time.Increasing heating power can increase the peak value of the maximum temperature diff erence on the tungsten rods,but has little eff ect on the occurrence time of the peak value of the maximum temperature diff erence on the tungsten rods.Increasing the heating power will increase the temperature diff erence of a single tungsten rod,but the temperature diff erence of a single tungsten rod never exceeds 65 K.This study can be used to guide the process optimization design.Combined with numerical simulation calculation,the sintering parameters with low energy consumption and high temperature uniformity can be quickly and eff ectively found,thus improving the microstructure and properties of sintered tungsten products.

关键词： Tungsten products Sintering Hydrogen flow rate Heating power

Detection of UAV Target Based on Continuous Radon Transform and Matched Filtering Process for Passive Bistatic Radar

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Journal of Beijing Institute of Technology 2024年第1期33卷 9-18页

作者： Luo Zuo Yuefei yan Jun Wang xin Sang yan Wang Dongming Ge Lihao ping Zhihai Wang Congsi Wang Guangzhou Institute of Technology Xidian UniversityGuangzhou 510555China National Laboratory of Radar Signal Processing Xidian UniversityXi’an710071China School of Information and Control Engineering Xi’an University of Architecture and TechnologyXi’anShaanxi 710055China CETC Wuhu Diamond Aircraft Manufacturing Co. LtdWuhuAnhui 241000China Beijing Space Vehicle General Design Department Beijing 100094China CETC No.38 Research Institute Hefei 230088China

Long-time integration technique is an effective way of improving target detection performance for unmanned aerial vehicle(UAV)in the passive bistatic radar(PBR),while range migration(RM)and Doppler frequency migration(DFM)may have a major effect due to the target maneuverability.This paper proposed an innovative long-time coherent integration approach,regarded as Continuous Radon-matched filtering process(CRMFP),for low-observable UAV target in passive bistatic radar.It not only mitigates the RM by collaborative research in range and velocity dimensions but also compensates the DFM and ensures the coherent integration through the matched filtering process(MFP).Numerical and real-life data following detailed analysis verify that the proposed method can overcome the Doppler mismatch influence and acquire comparable detection performance.

关键词： passive bistatic radar unmanned aerial vehicle long-time coherent integration Radon-matched filtering process

Model-driven path planning for robotic plasma cutting of branch pipe with single Y-groove based on pipe-rotating scheme

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Advances in Manufacturing 2024年第1期12卷 94-107页

作者： yan Liu Qiu Tang xin-Cheng Tian School of Control Science and Engineering Shandong UniversityJinan250061People’s Republic of China Engineering Research Center of Intelligent Unmanned System Ministry of EducationJinan250061People’s Republic of China School of Mechanical and Electronic Engineering Shandong Jianzhu UniversityJinan250101People’s Republic of China

The automatic cutting of intersecting pipes is a challenging task in manufacturing.For improved automation and accuracy,this paper proposes a model-driven path planning approach for the robotic plasma cutting of a branch pipe with a single Y-groove.Firstly,it summarizes the intersection forms and introduces a dual-pipe intersection model.Based on this model,the moving three-plane structure(a description unit of the geometric characteristics of the intersecting curve)is constructed,and a geometric model of the branch pipe with a single Y-groove is defined.Secondly,a novel mathematical model for plasma radius and taper compensation is established.Then,the compensation model and groove model are integrated by establishing movable frames.Thirdly,to prevent collisions between the plasma torch and workpiece,the torch height is planned and a branch pipe-rotating scheme is proposed.Through the established models and moving frames,the planned path description of cutting robot is provided in this novel scheme.The accuracy of the proposed method is verified by simulations and robotic cutting experiments.

关键词： Automatic groove cutting of intersecting pipes Model-driven robot path planning Plasma beam radius and taper compensation

Shedding light on gene therapy of Parkinson’s disease in non-human primates

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The Innovation 2024年第2期5卷 15-16页

作者： Xunyi yan xin Jin New Cornerstone Science Laboratory Center for Motor Control and DiseaseKey Laboratory of Brain Functional GenomicsEast China Normal University3663 North Zhongshan RoadShanghai 200062China NYU–ECNU Institute of Brain and Cognitive Science New York University Shanghai3663 North Zhongshan RoadShanghai 200062China

Parkinson’s disease(PD)is a progressive neurodegeneration disease initially described by James Parkinson.It is typically diagnosed based on clinical features such as bradykinesia,resting tremor,rigidity,and,in later stages,postural instability.Epidemiologically,the prevalence of PD ranges from 5 to over 35 cases per 100,000 population,with the majority affecting individuals aged 50 years or older.The risk increases with age,particularly in males.Various factors,including genetics,lifestyle,specific environmental influences,and geometry,contribute to the disease.

关键词： clinical rigidity initially