9 research outputs found

    The Solvability to the Compressible Isentropic Navier-Stokes Equations

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    众所周知,现实世界中许许多多的流体运动规律都可以用可压等熵~Navier-Stokes~方程来刻画.因此,对这类可压流体方程的研究不仅有理论意义,而且有重要的实际应用价值.本文主要研究粘性系数依赖密度的含真空的三维可压等熵~Navier-Stokes~方程的局部古典解存在性与一般初值常粘性系数的三维含真空可压等熵~Navier-Stokes~方程的整体光滑解存在性. 本文在第二章证明了粘性系数依赖于密度(~μ(ρ),lambda(ρ)\mu(\rho),\\lambda(\rho)~)、三维含真空可压等熵~Navier-Stokes~方程的局部古典解存在性.克服的主要困难是其中线性化技巧和非线性椭圆方程理论的应...It's well known that the Navier-Stokes equations is the model describing the motion of fluids. The research of compressible fluids has the important theory significance and strong application value. This article is mainly concerned with the local existence of classical solutions with density-dependent viscosity coefficients, and the global existence of classical solutions with general initial dat...学位:理学博士院系专业:数学科学学院_基础数学学号:1902010015395

    Singular Solution Of A Quasilinear Convection Diffusion Degenerate Parabolic Equation With Absorption

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    在这篇文章中我们讨论了一类P-Laplace方程的初值问题的非负非平凡解的存在性问题。In this paper, we are interested in the existence and nonexistence of non-negative and non-trivial solution of a P-Laplace equation's Cauchy problem .学位:理学硕士院系专业:数学科学学院数学系_基础数学学号:20032302

    以“听读后写”为特点的医务英语写作测试评分量表研究

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    语言测试中的行为测试常和专门用途英语测试相结合。本研究设计了一项模拟现实交际任务的医务英语写作行为测试:考生扮演医生的角色并完成对某位患者的诊断过程,在获得相关信息的基础上撰写英文病历书,测试形式以\"听读后写\"为特点,测试具有真实性。评分量表兼顾语言技能和基于特定工作的行业技能,体现现实交际任务的评价准则。三个评分分项分别为语言运用水平、对病情的理解和把握情况、病历书的结构和逻辑。评分结果分析表明,该量表具有较好的信度和效度。该测试的任务形式和评分量表都独具特色,对类似的专门用途英语测试的开发和研究具有一定的借鉴意义。2016年教育部人文社会科学研究青年基金项目“新TEM-8写作测试评分量表建构研究”(编号16YJC740029)阶段性成果之一,“第四届全国外语测试学术研讨会”宣读论

    基于人工智能技术的火电厂燃煤锅炉智能燃烧优化研究及应用

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    为了降低火电厂燃煤锅炉的氮氧化合物排放浓度和锅炉煤耗,提出了样本增量量子神经网络和改进型量子蜂群算法。样本增量量子神经网络可以动态建立燃煤锅炉的氮氧化合物排放浓度和锅炉煤耗的综合模型,并且可实现模型滚动优化。基于建立的综合模型,通过应用改进型量子蜂群算法优化一二次风量、燃煤量和各二次风门开度来实现锅炉燃烧优化。基于上述两种方法,开发了一套燃煤锅炉智能燃烧优化软件,并应用于某热电厂330 MW锅炉上,测试结果表明,氮氧化合物排放浓度和锅炉煤耗均有不同程度的降低,说明建模方法和优化算法是有效的

    纳米能源技术研究态势分析

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    &nbsp; &nbsp; &nbsp;本书对美国、欧盟、日本、中国的纳米能源相关战略部署和项目规划进行了调研;对纳米能源领域的重点研究前沿进行遴选和解读分析,以期呈现纳米能源领域的研究热点和趋势;利用专利数据对纳米光伏、纳米电极、纳米发电机、资源小分子纳米催化剂四个主题方向进行了技术研究态势分析,以期对我国的纳米能源技术发展提供有益的参考。 &nbsp; &nbsp; 本书适合政府科技管理部门、科研机构管理部门、科技战略研究人员,以及纳米科技和能源科技领域的研究人员阅读参考。</p

    Asymmetric syntheses of (8R,8aS)-and (8R,8aR)-8-hydroxy-5-indolizidinones:Two promising oxygenated indolizidine building blocks

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    以3-苄氧基哌啶-2,6-二酮衍生物20为起始原料,分别合成了两类新的合成砌块(8r,8AS)-及(8r,8Ar)-8-羟基-5-吲哚里西啶酮19A/19b和15A/15b.19A/19b的合成是基于反式非对映立体选择性还原烷基化反应(dr=93:7),接着经4步转化而成;而化合物15A/15b的制备则以双烯29的rCM反应为关键步骤,再经顺式立体选择性催化氢化(dr=91:9)反应完成.此外,还原化合物15A得到了(8r,8Ar)-8-羟基-5-吲哚里西啶18.Starting from the oxygenated piperidine building block 20,two synthetic approaches to new building blocks(8R,8aS) -and(8R,8aR) -8-hydroxy-5-indolizidinones 19a/19b and 15a/15b have been developed,respectively.The first one is based on the trans-diastereoselective reductive alkylation(dr=93:7) ,followed by a four-step procedure;and the second one called for the RCM reaction on the N,O-acetal derived from a vinylation,which was followed by a pyrrole formation,and a stereocontrolled cis-selective(dr=91:9) catalytic hydrogenation.Reduction of the diastereomer 15a produced(8R,8aR) -8-indolizidinol(18).国家自然科学基金(20672089;20832005);国家基础科学人才培养基金(J1030415);国家重点基础研究发展计划(973项目;2010CB833200)的资

    Effects of Spartina alterniflora Invasion on Soil Carbon, Nitrogen, Phosphorus and Their Ecostoichiometric Characteristics in the Yellow River Estuary Wetlands

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    Spartina alterniflora invasion has severely threatened the ecological integrity of coastal wetland ecosystems. The carbon, nitrogen, phosphorus and ecostoichiometric characteristics of soils in different layers were investigated under different stages of S. alterniflora invasion in the Yellow River Estuary wetlands. Using the method of substituting space for time, 0-100 cm soil samples were collected in wetlands of different stages of S. alterniflora invasion (SA3, invaded in 2016;SA8, invaded in 2011;SA13, invaded in 2006)and uninvaded bare flats (SA0). The contents of total carbon (TC), total nitrogen (TN)and total phosphorus (TP), were then measured and analyzed by the stoichiometric ratios of carbon, nitrogen and phosphorus. Results showed that (1)S. alterniflora invasion increased the content of TC and TN in surface soils, but had little effects on TP. (2)TC contents in the 0-10 cm soil layer of SA16, SA11 and SA06 were 18.9%, 27.6% and 57.6% higher than that of SA0, respectively, and TN contents were 1.39, 2.37 and 3.66 times higher than that of SA0, respectively. (3)S. alterniflora invasion didn't significantly affect soil w(C)/w(N), but increased w(C)/w(P)and w(N)/w(P)in shallow soils, and decreased w(C)/w(P)and w(N)/w(P)in deep soils. The order of soil w(C)/w(P)and w(N)/w(P)in the 0-10 cm soil layer was SA13>SA8>SA3>SA0. In the 0-100 cm soil layer, the order of soil w(C)/w(N)was SA0>SA8>SA13>SA3, that of soil w(C)/w(P)was SA13>SA8>SA0>SA3, and that of soil w(N)/w(P)was SA13>SA0>SA3>SA8. In the 0-100 cm soil layer, soil pH, electrical conductivity, bulk density and water content were important environmental factors affecting the contents of carbon, nitrogen and phosphorus. There were no significant correlations between w(C)/w(N)and soil environmental factors, but w(C)/w(P)and w(N)/w(P)were significantly correlated with environmental factors. In conclusion, S. alterniflora invasion changed the contents of soil carbon and nitrogen in the salt marsh wetlands of the Yellow River Estuary and affected the balance of soil nutrient resources

    基于附加参数光束法平差的非量测型数码相机检校研究/Calibration of a Nonmetric Camera Based on Bundle Adjustment with Additional Parameters[J]

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    本文主要研究利用附加参数光束法平差和高精度的室内三维检校场对非量测型数码相机进行内方位元素和镜头光学畸变差的测定.论文详细阐述了利用附加参数光束法平差进行相机检校的原理,实现过程,并对检校参数进行了精度评定和可靠性验证.实验结果表明经该方法进行检校的相机可用于大比例尺摄影测量
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