检索结果-南通市图书馆

竖直加热平板自然对流边界层中流动稳定性与转捩过程的实验研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

北京大学学报（自然科学版） 1999年第3期35卷 340-345页

作者：陶建军颜大椿北京大学力学与工程科学系

对恒壁温竖直加热平板的自然对流边界层的流动稳定性与转捩过程进行了试验研究，研究结果表明在外层速度剖面拐点处测得的线性不稳定波的特性与Ｂｒｅｗｓｔｅｒ和Ｇｅｂｈａｒｔ的计算基本一致。在低频成分首先增长后，随着Ｇｒａｓｈ... 详细信息

对恒壁温竖直加热平板的自然对流边界层的流动稳定性与转捩过程进行了试验研究，研究结果表明在外层速度剖面拐点处测得的线性不稳定波的特性与Ｂｒｅｗｓｔｅｒ和Ｇｅｂｈａｒｔ的计算基本一致。在低频成分首先增长后，随着Ｇｒａｓｈｏｆ数的增加高频成分迅速发展，在湍流化过程中逐渐形成浮力子区；与此同时，在内层近壁处的测量发现，在更高频段存在一种具有较强选频特性的不稳定波及其亚谐波，并在转捩后期Ｇｒ≈３７８６时于其频谱的高频一侧逐渐形成惯性子区。

关键词：自然对流边界层稳定性竖直加热平板

大规模激光相干合成主动相位控制技术研究进展

在线全文

学校读者我要写书评

暂无评论

强激光与粒子束 2024年第6期36卷 1-23页

作者：周宏冰张昊宇李敏冯曦谢亮华刘玙楚秋慧闫玥芳陶汝茂林宏奂王建军颜立新景峰中国工程物理研究院激光聚变研究中心四川绵阳621900 清华大学加速器实验室北京100084

大规模激光相干合成是突破单口径激光特性极限、获得超高峰值/平均功率、超大脉冲能量、超高空/谱亮度等极端特性激光的有效技术路径之一,而大规模激光相干合成的关键是主动相位控制。主动相位控制技术可以对各路光束相位进行主动控制,... 详细信息

大规模激光相干合成是突破单口径激光特性极限、获得超高峰值/平均功率、超大脉冲能量、超高空/谱亮度等极端特性激光的有效技术路径之一,而大规模激光相干合成的关键是主动相位控制。主动相位控制技术可以对各路光束相位进行主动控制,补偿相位噪声引起的相干特性退化、合成效率下降,获得高品质的合成激光。自相干合成技术提出以来,研究人员开发了多种主动相位控制方法用于相干合成相位校正,其中适用于大规模激光相干合成的主动相位控制方法也得到了飞速发展。系统梳理了大规模激光相干合成的主动相位控制方法,深入分析了不同方法的原理、特点、适用场景和扩展能力,介绍了不同方法取得的相干合成研究最新进展及标志性成果,报道了19通道闭环上升时间仅6μs的相干合成锁相控制突破性结果,最后总结和展望了主动相位控制方法的发展趋势。

关键词：相干合成主动相位控制多抖动随机并行梯度下降机器学习

Thermogravimetric analysis of bamboo-tar under different heating rates based on distributed activation energy model

在线全文

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2018年第6期11卷 180-186页

作者： Huan Zhang Beibei yan Tingzhou Lei tao Liu jianjun Hu Yameng Li Guanyi Chen School of Environmental Science&Engineering Tianjin UniversityTianjin 300350China Collaborative Innovation Center of Biomass Energy Henan Agricultural UniversityZhengzhou 450002China Energy Institute Henan Academy of SciencesZhengzhou 450002China College of Resources and Environment Henan University of Economics and LawZhengzhou 450002China

Carbon fiber is a kind of new polymer material with excellent mechanical properties and being applied *** process of carbon fiber prepared by bamboo tar,including extraction,condensation,spinning,oxidation and carbonation,is influenced by the pyrolysis kinetics *** this paper,the thermogravimetric analysis(TGA)of bamboo tar produced in the process of pyrolysis and gasification of the bamboo which is known as Phylostachys sulphurea,was analyzed by the distributed activation energy model(DAEM)to understand the kinetic properties and parameters of bamboo *** thermogravimetric analysis of bamboo tar which is used as the raw material of carbon fiber was conducted under 5 different heating rates(i.e.5,10,15,30 and 50℃/min,etc.)in nitrogen *** results show that the activation energy of bamboo tar and the exponential factor increased significantly with the increase of the heating rate,and the low heating rate is advantageous to the extraction of bamboo tar solvent and the thermal polycondensation,which can provide scientific reference for the optimization of carbon fiber *** thermal weight results show that the temperature range of bamboo tar being decomposed rapidly is 213℃-410℃.The ranges of the activation energy were calculated by DAEM,which have small difference in comparisons with five heating rates when the conversion rate is at 0.1-0.6 and the average value of the activation energy is 119 kJ/*** stability range of the activation energy is enlarged when the conversion rate is greater than 0.6 and heating rate increases.

关键词： bamboo tar carbon fiber thermogravimetric analysis(TGA) distributed activation energy model(DAEM)

Optimization on transport of charge carriers in cathode of sulfide electrolyte-based solid-state lithium-sulfur batteries

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

Nano Research 2023年第6期16卷 8139-8158页

作者： Zengqi Zhang yantao Wang tao Liu Gang Li Jun Ma jianjun Zhang Pengxian Han Shanmu Dong Xuedong yan Yue Tang Guanglei Cui Qingdao Industrial Energy Storage Research Institute Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao 266101China School of Future Technology University of Chinese Academy of SciencesBeijing 100049China College of Chemical Engineering Ningbo PolytechnicNingbo 315800China The Biodesign Institute and School of Molecular Sciences Arizona State University TempeArizona 85287USA

Lithium-sulfur(Li-S)batteries are considered as promising candidates for novel energy storage technology that achieves energy density of 500 Wh·kg^(−1).However,poor cycle stability resulting from notorious shuttle effect and the safety concerns deriving from flammability of ether-based electrolyte hinder the practical application of Li-S *** of low solubility to polysulfide,high ionic conductivity,and safety property,sulfide-based electrolytes can fundamentally address above *** is widely known that the effective transports of both electrons and ions are basic requirement for redox reaction of active materials in ***,construction of fast and stable ionic and electronic transport paths in cathode is especially pivotal for cycle stability of solid-state Li-S batteries(SSLSBs).In this review,we provide research progresses on facilitating transport of charge carriers in composite cathode of *** perspective of materials,intrinsically conductivity of electrolyte and carbon shows dramatic effect on migration of charge carriers in cathode of SSLSBs,thereby the conductive additives are summarized in the ***,the charge transport in cathode of SSLSBs fully depends on the physical contact between active materials and conductive additives,therefore we summarized the strategies optimizing interfacial contact and reducing interfacial ***,potential future research directions and prospects for SSLSBs with improved energy density and cycle performance are also proposed.

关键词： sulfide electrolyte charge transport composite cathode solid-state lithium-sulfur battery

新外来中药玛咖对甲状腺功能调节作用和安全性实验研究

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

世界中医药 2024年第11期19卷 1555-1562页

作者：陈彦王林元陈亚文陶然李爱民张睿张建军费文婷吴晓磊北京中医药大学中药学院北京100029 烟台新时代健康产业有限公司烟台264006 国珍健康科技〔北京〕有限公司北京102206 北京中医药大学中医学院北京100029

目的:探究新外来中药玛咖对正常大鼠和甲状腺肿大鼠甲状腺功能的调节作用,并观察其安全性。方法:采用Wistar雌性大鼠探究玛咖对甲状腺肿大鼠甲状腺功能调节作用和安全性,随机数字表法随机分为对照组、模型组、阳性药组、玛咖高剂量组、... 详细信息

目的:探究新外来中药玛咖对正常大鼠和甲状腺肿大鼠甲状腺功能的调节作用,并观察其安全性。方法:采用Wistar雌性大鼠探究玛咖对甲状腺肿大鼠甲状腺功能调节作用和安全性,随机数字表法随机分为对照组、模型组、阳性药组、玛咖高剂量组、玛咖低剂量组。通过灌胃丙硫氧嘧啶(PTU)4周复制甲状腺肿模型,同时阳性药组,玛咖高、低剂量组分别给予相应药物。观察各组大鼠甲状腺组织病理形态,甲状腺系数,甲状腺激素合成、调控等相关指标;观察大鼠肝、肾组织形态和肝肾功能相关指标。采用Wistar雌性大鼠探究玛咖对正常大鼠甲状腺功能的调节作用,随机分为对照组和4个不同剂量的玛咖组。除对照组外,其余4组分别给予相应药物。统计甲状腺系数,测定大鼠甲状腺激素合成、调控等相关指标。结果:与模型组比较,玛咖组大鼠的体质量升高(P0.05),甲状腺系数、甲状腺和肝肾组织形态无明显差异。玛咖对正常大鼠体质量、甲状腺系数、T_(3)、T_(4)、FT_(3)、FT_(4)、TSH、TRH、Tg、TPO和TSHR水平无影响(P>0.05)。结论:玛咖对甲状腺肿异常状态的甲状腺功能减退具有一定的治疗作用,对正常大鼠的甲状腺功能没有不良影响,且未发现玛咖对甲状腺肿大鼠的安全性问题。

关键词：玛咖甲状腺激素安全性甲状腺肿甲状腺功能减退肝肾功能实验研究新外来中药

Fouling community characteristics in subtropical coastal waters of the southwestern East China Sea

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2017年第10期36卷 70-78页

作者： LIN Heshan WANG jianjun LIU Wei LIU Kun ZHANG Shuyi HE Xuebao HUANG Yaqin LIN Junhui MOU Jianfeng ZHENG Chengxing yan tao Laboratory of Marine Biology and Ecology Third Institute of Oceanography State Oceanic Administration Ning De Marine Environmental Monitoring Center CAS Key Laboratory of Tropical Marine Bio-resources and Ecology South China Sea Institute of OceanologyChinese Academy of Sciences

A fouling study was conducted in coastal waters southwest of the East China Sea between December 2013 and November 2014. A total of 84 species of fouling organisms belonging to 69 genera, 49 families, and 10 phyla were recorded over the entire year. The community composition was dominated by coastal warm-water species belonging to typical subtropical inner bay communities. The prosperous stage of settlement lasted from April to September, and the adhesion strength of the fouling organisms was the highest in summer. Sessile suspension feeders constituted the main core of settlement for the fouling community. Amphibalanus reticulatus was the most dominant and representative species of fouling organism, and other dominant species included Caprella equilibra, Ectopleura crocea, Anthopleura nigrescens, Stylochus ijimai, Spirobranchus kraussii, Crassostrea angulata, Perna viridis, Jassa falcata, Stenothoe valida, Sphaerozius nitidus, and Biflustra grandicella. The individuals in the fouling community showed a mutual dependence or constraint relationship due to competition for settlement space and food, and they exhibited a particular spatiotemporal distribution in accordance with adaptation to environmental factors. Temperature was the most important environmental factor determining the geographic distribution of fouling organisms. The temperature characteristics of species essentially reflect the differences in the fouling community composition in various climate zones. The species number, settlement stage, and settlement rate of fouling organisms are closely related to water temperature. Local natural environmental conditions（salinity, water currents, light, etc.） as well as human activity（such as aquaculture production） are all important factors affecting the settlement of fouling organisms.

关键词： biofouling coastal waters East China Sea community structure

A novel approach to melt purification of magnesium alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2016年第1期4卷 8-14页

作者： Fusheng Pan Xianhua Chen tao yan Tingting Liu jianjun Mao Wei Luo Qin Wang Jian Peng Aitao Tang Bin Jiang College of Materials Science and Engineering Chongqing UniversityChongqing 400045China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400045China Chongqing Academy of Science and Technology Chongqing 401123China

A novel low-cost method for melt purification of magnesium alloys,the melt self-purifying technology(MSPT),has been developed successfully based on a low temperature melt treatment(LTMT)without adding any *** iron solubility in the molten liquid of magnesium and its alloys,and the settlement velocity of iron particles were *** is shown that the low temperature melt treatment is an effective method to decrease the impurity Fe content in magnesium and its *** any additions,the Fe content in the AZ31 alloy was reduced to 15 ppm from the initial 65 ppm,and the Fe content in the AZ61 melt was decreased to 20 ppm from the initial 150 ppm after the low temperature melt *** results also showed that the Fe content in AM60 and AM50 dropped to 15 and 18 ppm,respectively,from the initial 150 ppm after the low temperature melt *** ZK 60,the Fe content in the melt down to less than 5 ppm was *** the low temperature melt treatment,the Si content in the above alloys was also decreased obviously.

关键词： Magnesium alloys Purification Impurity Melt Iron Silicon

Symptom clustering in chronic gastritis based on spectral clustering

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 Traditional Chinese Medicine 2014年第4期34卷 504-510页

作者： Wenhua Zhu Zhaoxiang Fan Guoping Liu jianjun yan tao Zhong Wu Zheng Ruiqing Wang Chunying Wang Basic Medical College Shanghai University of Traditional Chinese Medicine Center for Mechatronic Engineering EastChina University of Science and Technology

OBJECTIVE: Apply spectral clustering to analyze the patterns of symptoms in patients with chronic gastritis(CG).METHODS: Based on 919 CG subjects, we applied mutual information feature selection to choose the positively correlated symptoms with each ***, we used the Shi and Malik spectral clustering algorithm to select the top 20 correlated ***: We ascertained the results of six *** were three categories for the pattern of accumulation of damp heat in the spleen-stomach(0.00332). There were six categories for the pattern of dampness obstructing the spleen-stomach(0.02466). There were two categories for the pattern of spleen-stomach Qi deficiency(0.013 89).There were three categories for the pattern of spleen-stomach deficiency cold(0.009 15). There were five categories for the pattern of liver-Qistagnation(0.01910).There were four categories for the pattern of stagnant heat in the liver-stomach(0.00585).CONCLUSION: Most of the spectral clustering results of the symptoms of CG patterns were in accordance with clinical experience and Traditional Chinese Medicine theory. Most categories suggested the nature and/or location of the disease.

关键词： Gastritis Cluster analysis Pattern Symptom complex

Principle and numerical demonstration of high power all-fiber coherent beam combination based on self-imaging effect in a square core fiber

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2022年第2期10卷 444-455页

作者： Yuefang yan Yu Liu Haoyu Zhang Yue Li Yuwei Li Xi Feng Donglin yan jianjun Wang Honghuan Lin Feng Jing Wenhui Huang Rumao tao Laser Fusion Research Center China Academy of Engineering PhysicsMianyang 621900China Key Laboratory of Particle&Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

The self-imaging effect in a square core fiber has been investigated, and an integrated all-fiber combiner has been proposed based on a large mode area double clad fiber, which can be employed to construct high power coherent beam combining sources in the all-fiber format. The influence of various parameters on beam quality(M^(2)) and efficiency of the all-fiber coherent beam combiner has been studied numerically, which reveals that the near diffraction-limited laser beam can be achieved. A principle demonstration of the self-imaging effect has been carried out experimentally in a square core fiber, which proves the feasibility of beam combining with the square fiber, and that it is a promising way to develop high power coherent beam combination sources.

关键词： fiber power beam