检索结果-南通市图书馆

Particle convective heat transfer near the wall in a supercritical water fluidized bed by single particle model coupled with CFD-DEM

在线全文

学校读者我要写书评

暂无评论

Particuology 2023年第2期73卷 47-58页

作者： Tianning Zhang zhen wan Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Electronic Engineering Research Institute Xi'an710100ShaanxiChina

Supercritical water fluidized bed(SCWFB)is a promising reactor to gasify biomass or coal.Its optimization design is closely related to wall-to-bed heat transfer,where particle convective heat transfer plays an important role.This paper evaluates the particle convective heat transfer coefficient(h_(pc))at the wall in SCWFB using the single particle model.The critical parameters in the single particle model which is difficult to get experimentally are obtained by the computational fluid dynamics-discrete element method(CFD-DEM).The contact statistics related to particle-to-wall heat transfer,such as contact number and contact distance,are also presented.The results show that particle residence time(τ),as the key parameter to evaluate h_(pc),is found to decrease with rising velocity,while increase with larger thermal boundary layer thickness.τfollows a gamma function initially adopted in the gas-solid fluidized bed,making it possible to evaluate h_(pc) in SCWFB by a simplified single particle model.The theoretical predicted h_(pc) tends to increase with rising thermal gradient thickness at a lower velocity(1.5 U_(mf)),while first decreases and then increases at higher velocity(1.75 and 2 U_(mf)).h_(pc) occupies 30%-57%of the overall wall-to-bed heat transfer coefficient for a particle diameter of 0.25 mm.The results are helpful to predict the overall wall-to-bed heat transfer coefficient in SCWFB combined with a reasonable fluid convective heat transfer model from a theoretical perspective.

关键词： Supercritical water Fluidized bed Particle residence time Discrete element method Single particle model

Greatly increased visible-light photocatalytic activity of SnS_(2)/carbon nanotube composite for Cr(VI)reduction:Insights into effects of solid acid structure

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

Journal of Materials Science & Technology 2023年第30期161卷 233-244页

作者： zhen wan Qihang Mao Jingjing Xiang Dongge Ma Heqing Tang Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education College of Resources and Environmental ScienceSouth-Central Minzu UniversityWuhan 430074China Department of Chemistry College of Chemistry and Materials EngineeringBeijing Technology and Business UniversityBeijing 100048China

A composite of SnS_(2)and carbon nanotube(CNT)was successfully synthesized as a visible-light-driven photocatalyst with a mechanochemical method.In comparing with SnS_(2),the SnS_(2)/CNT composite im-proved much the photocatalytic removal of Cr(VI)in acidic condition,which was confirmed to its special solid acid structure.During the synthesis of the SnS_(2)/CNT composite by ball milling,S-C p-πbonding was formed between sulfur atoms in SnS_(2)and carbon atoms in CNT.The generated S-C p-πbonding enhanced the transfer of photo-induced electrons in the bulk phase of the composite photocatalyst un-der visible light irradiation.Moreover,the persistent radical sites on CNT were able to trap photo-induced electrons and served as conjugated acid sites in the photocatalysis,which increased surface concentration of protons through their association with H+.These made the catalyst have a solid acid structure with plentiful surface protons,promoting the interfacial electron transfer between the catalysts and Cr(VI)and increasing the source of H+for the reduction of Cr(VI).As a result,the photocatalytic reduction rate of Cr(VI)on the SnS_(2)/CNT composite were dramatically enhanced,being about 800%that on SnS_(2).On the basis of various characterizations and probe experiments,we confirmed the significance of the solid acid structure of the photocatalyst and clarified the catalytic mechanism of the new photocatalyst.Our finding may provide a new strategy to prepare highly active photocatalysts for proton-involved reactions.

关键词： SnS_(2)/CNT composite S-C p-πbonding Solid acid Ball milling Cr(VI)reduction

Instantaneous mixing characteristics of binary mixtures differing in density in a gas-solid fluidised bed

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

Particuology 2020年第6期18卷 63-71页

作者： zhen wan Youjun Lu Hao wang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

Characterisations of instantaneous mixing behaviours in fluidised beds with binary mixtures has many challenges.We studied the instantaneous mixing characteristics of binary mixtures in a 2-D quasi gas-solid fluidised bed using a capacitance probe method.This method enabled the quantitative assessment of instantaneous mixing behaviours,including mixing index,rate,and time.Three kinds of binary mixtures of similar size but different density were used for the transient and steady fluidisation experiments in a bubbling fluidised bed.The mixing curves of initially segregated binary mixtures were acquired,and the instantaneous characteristics for the entire process were analysed.An equation was proposed to describe the mixing process and predict the mixing degree over time.By comparing experiments with different working conditions,the effects of superficial gas velocity and density ratio on the mixing in the centre and at the wall of the fluidised bed were addressed.During the stable fluidisation stage,the axial concentration profiles of the mixtures were obtained,and the mechanisms of mixing were discussed.Results showed that the mixing level increased logarithmically with time and eventually reached a relatively stable value.Increasing the superficial gas velocity and reducing the density ratio promoted mixing and reduced mixing time.High superficial gas velocities tended to mix the mixtures well and quickly,regardless of the density ratio of the two components.

关键词： Binary mixtures Fluidised bed Mixing Instantaneous characteristics

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

香港地区高校图书馆科研支持服务实践及启示

大学图书情报学刊 2024年第3期42卷 95-102页

作者：邢婉贞常州大学图书馆 213164

开展科研支持服务已成为高校图书馆高质量发展的必然趋势。文章对香港地区高校图书馆网站进行总体调查,根据各高校图书馆网站科研支持服务情况,选取科研支持服务开展较好的8所高校图书馆,对其科研支持服务栏目、团队、项目、具体开展情... 详细信息

开展科研支持服务已成为高校图书馆高质量发展的必然趋势。文章对香港地区高校图书馆网站进行总体调查,根据各高校图书馆网站科研支持服务情况,选取科研支持服务开展较好的8所高校图书馆,对其科研支持服务栏目、团队、项目、具体开展情况做了详细分析。分析发现,上述图书馆在科研准备阶段、开展阶段、成果出版和共享阶段、成果保存与评价阶段,服务项目虽不尽相同,但都较全面且具有特色。通过总结其成功经验,得出内地高校图书馆科研支持服务可以从树立服务理念、寻求多方合作、整合相关资源、提升馆员能力、建立反馈系统五个方面进行借鉴和参考。

关键词：图书馆服务科研支持科研服务香港地区高校图书馆

维普期刊数据库博看期刊

大口径辅助阳极型辉光放电溅射源的设计与研究

在线全文

学校读者我要写书评

暂无评论

光谱学与光谱分析 2024年第6期44卷 1640-1647页

作者：万真真武佳施宁王永清刘少锋沈懿璇王海云河北大学电子信息工程学院河北保定071002 北京科技大学国家材料服役安全科学中心北京100083

辉光放电原子发射光谱分析技术可对金属样品表面进行沿深度方向的逐层分析与表征,具有溅射速率快、分析效率高、可大面积溅射的优点。另外,辉光放电等离子体能量较低,材料逐层溅射激发过程中不易引起材料本身组织结构的变化,能够实现沿... 详细信息

辉光放电原子发射光谱分析技术可对金属样品表面进行沿深度方向的逐层分析与表征,具有溅射速率快、分析效率高、可大面积溅射的优点。另外,辉光放电等离子体能量较低,材料逐层溅射激发过程中不易引起材料本身组织结构的变化,能够实现沿样品深度方向逐层剥蚀制样。将辉光放电溅射源与扫描电镜、光谱分析检测仪器等联用,可作为金属材料高通量定量表征的有效手段。为了高通量地获取材料表面的成分分布信息,需要对材料表面在多尺寸、大面积溅射条件下进行辉光放电等离子体溅射。因此在传统辉光溅射源的基础上,改进了阳极筒结构,设计了4种直径为cm级的(15、20、30和40 mm)大口径阳极筒,并对其进行COMSOL数值模拟仿真和实际溅射效果研究。大尺寸溅射面可获得材料表面更为丰富的信息,但在相同溅射条件下,阳极口径增大也带来溅射速率下降、溅射面中心区域离子化率降低、影响溅射均匀性和坑型平整度等问题。为解决这些问题,设计了可应用于大口径直流辉光放电溅射源的辅助阳极结构,通过改变放电空间的电场分布情况调控等离子体分布,增强了阳极中心区域离子化率。详细阐述了辅助阳极结构的设计原理,并对传统阳极和辅助阳极进行了数值模拟仿真研究和实际溅射效果对比实验。结果表明增设辅助阳极对大口径溅射源溅射速率的提升效果明显,对阳极口径30 mm溅射源的溅射速率提升33%~48%,对阳极口径40 mm溅射源的溅射速率提升34%~57%。采用大口径辅助阳极型溅射源对紫铜样品进行了溅射激发,并用光学相干断层扫描仪(OCT)测试了溅射坑形貌,结果表明增设辅助阳极可有效改善溅射均匀性和坑型平整度。

关键词：辉光放电高通量表征辅助阳极溅射速率溅射坑形貌

在线全文

学校读者我要写书评

暂无评论

鸡鸣口引水枢纽坝型比选研究

山东水利 2024年第3期 46-48页

作者：万珍中工武大设计集团有限公司湖北武汉430205

根据鸡鸣口引水枢纽地形地质条件等基本资料,对自密实块石混凝土拱坝、混凝土重力坝和混凝土闸坝3种坝型方案进行技术经济比较,依据比较结果,推荐鸡鸣口引水枢纽采用自密实块石混凝土拱坝坝型。

关键词：鸡鸣口水电站坝型比选自密实块石混凝土拱坝

Preliminary limits of a logarithmic correction to the Newtonian gravitational potential in binary pulsars

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第10期14卷 1301-1306页

作者： Chang Lu Zi-Wei Li Sheng-Feng Yuan zhen wan Song-He Qin Kai Zhu Yi Xie School of Astronomy and Space Science Nanjing University Key Laboratory of Modern Astronomy and Astrophysics Nanjing UniversityMinistry of Education

We obtain preliminary limits on a logarithmic correction to the Newtonian gravitational potential by using five binary pulsars： PSR J0737-3039, PSR B 1534＋12, PSR J 1756-2251, PSR B 1913＋ 16 and PSR B2127＋ 11C. This kind of correction may originate from fundamental frameworks, like string theories, effective models of grav- ity due to quantum effects and the non-local gravity scheme. We estimate the upper limit of the Tohline-Kuhn-Kruglyak parameter A and the lower limit of the Fabris- Campos parameter α, which parameterize the correction and are connected to each other by αλ = -1. By analyzing the advances of periastron of these binary pulsars, we find that the preliminary upper limit of a is 0.19 ± 0.14 kpc^-1 and the prelimi- nary lower limit of ）, is -5.2 4± 3.8 kpc. They are compatible with the bounds based on dynamics of spiral galaxies but quite different from those given by solar system dynamics. These results indicate that this logarithmic correction might be more ob- servable in current timings of binary pulsars than in motions of the solar system.

关键词： gravitation -- relativity -- pulsars individual （PSR 0737-3039, PSRB 1534＋12, PSR J1756-2251, PSR B1913＋16, PSR B2127＋11C）

有氧运动对自发性高血压大鼠心肌内皮型一氧化氮合酶解耦联的影响

在线全文

学校读者我要写书评

暂无评论

中华物理医学与康复杂志 2024年第3期46卷 193-198页

作者：寇冠万震刘晓哲牛晓阳郑州航空工业管理学院体育与健康促进研究中心郑州450046 河南省人民医院检验科郑州430003 郑州大学第五附属医院郑州450001

目的观察规律有氧运动对自发性高血压大鼠(SHR)心脏重塑的影响,并探讨内皮型一氧化氮合酶(eNOS)解耦联在其间的作用机制。方法采用随机数字表法将30只6周龄健康雄性SHR大鼠分为安静组和运动组,每组15只;同时选取10只鼠龄、性别相匹配的W... 详细信息

目的观察规律有氧运动对自发性高血压大鼠(SHR)心脏重塑的影响,并探讨内皮型一氧化氮合酶(eNOS)解耦联在其间的作用机制。方法采用随机数字表法将30只6周龄健康雄性SHR大鼠分为安静组和运动组,每组15只;同时选取10只鼠龄、性别相匹配的Wistar-Kyoto大鼠纳入正常对照组。将正常对照组和安静组大鼠置于鼠笼内安静饲养,运动组大鼠则给予8周中等强度跑台运动干预,每周运动5次。于末次训练结束48 h后采用超声心动图设备检测各组大鼠心脏结构及功能,分别对其心肌组织进行麦胚凝集素和天狼星红染色,观察病理学改变并获取心肌细胞横截面积(CSA)及间质胶原容积分数(CVF),采用TUNEL染色法检测心肌细胞凋亡率,采用高效液相色谱法测定心肌四氢生物喋呤(BH4)含量,采用Western blot法检测心肌组织eNOS总蛋白、eNOS二聚体及单体蛋白表达量。结果与正常对照组比较,安静组左心室壁厚度(LVWT)、心肌CSA和CVF升高(P0.05)。3组大鼠eNOS总蛋白含量组间均无明显差异(P>0.05)。结论规律有氧运动可能通过调控eNOS解耦联改善SHR大鼠心脏重塑。

关键词：有氧运动高血压心脏重塑内皮型一氧化氮合酶解耦联

基于真实情境的初中化学问题导向式教学实践——探究过氧化氢分解原理与催化剂的特点

在线全文

学校读者我要写书评

暂无评论

化学教育（中英文） 2024年第3期45卷 60-65页

作者：范婉贞侯晓蓓张惠敏广东广雅中学广东广州510160 深圳市福田区外国语学校(香蜜) 广东深圳518000 深圳市宝安中学(集团)第二外国语学校广东深圳518125

《义务教育化学课程标准(2022年版)》提出了化学学科发展学生的4大核心素养,倡导在发挥化学学科价值的同时,引导学生解决真实情境中的跨学科问题,应对未来充满不确定性的挑战。过氧化氢制备氧气的教学存在缺乏贴切的真实情境、课堂实验... 详细信息

《义务教育化学课程标准(2022年版)》提出了化学学科发展学生的4大核心素养,倡导在发挥化学学科价值的同时,引导学生解决真实情境中的跨学科问题,应对未来充满不确定性的挑战。过氧化氢制备氧气的教学存在缺乏贴切的真实情境、课堂实验缺乏可操作性、知识要点难以全面论证、缺乏定量思维的发展等问题。本研究以肿瘤缺氧治疗为情境,问题导向贯穿情境、创新实验生成情境、智慧平板服务情境、任务驱动推进情境,让学生体验科研工作者研究的全过程,有效完成过氧化氢分解原理和催化剂特点的教学。

关键词：真实情境问题导向过氧化氢分解催化剂