多对极发电机励磁绕组匝间短路故障在线定位理论研究

大型水轮发电机和抽水蓄能发电电动机均为多对极,现场迫切希望实现故障磁极的在线定位.本文基于一台3对极、12kW的发电机动模样机研究在线定位的理论基础.首先,采用场路结合法对该样机在联网工况下的励磁绕组匝间短路故障进行了计算,并与实验结果进行了对比和分析,验证了计算模型的正确性.然后,利用故障数学模型对该样机一极短路故障...     

城市污泥掺量对煤气化渣陶粒性能影响

以煤气化渣为主要原材料烧制陶粒,研究了陶粒的烧结制度以及城市污泥掺量对陶粒性能、孔结构影响及微观作用机制.结果表明:陶粒烧结制度为500℃预热30 min,1100℃烧结15 min时,煤气化渣陶粒强度可达11.3 MPa,且烧结出污泥质量掺量为20％、筒压强度为6.7 MPa的轻质高强陶粒;城市污泥掺量改变了陶粒孔结...     

An integrated multi-energy flow calculation method for electricity-gas-thermal integrated energy systems

The modeling and multi-energy flow calculation of an integrated energy system (IES) are the bases of its operation and planning. This paper establishes the models of various energy sub-systems and the coupling equipment for an electricity-gas-thermal IES, and an integrated multi-energy flow calculation model of the IES is constructed. A simplified calculation method for the compressor model in a natural gas network, one which is not included in a loop and works in constant compression ratio mode, is also proposed based on the concept of model reduction. In addition, a numerical conversion method for dealing with the conflict between nominal value and per unit value in the multi-energy flow calculation of IES is described. A case study is given to verify the correctness and speed of the proposed method, and the electricity-gas-thermal coupling interaction characteristics among sub-systems are studied.     

欧美军用红外通用组件技术的发展现状及趋势

在军用红外技术的早期发展阶段,欧美基于热成像系统关键部件的通用化形成了通用组件概念.通用组件虽然减少了工程上选择不同技术方案的余地,但是降低了热成像系统的研发成本和使用维护费用,有利于批量生产.美国以一代通用组件为基础形成了SADA系列组件,在SADA基础上推出的水平技术集成(Horizontal Technology Integration,HTI)项目,实现了军用热像仪的批量生产和装备.介绍了欧美通用组件技术的发展历史和现状.随着探测器、微电子等相关技术的发展,通用组件已经从原来的Common Module转变为Module.     

城市污泥对固废陶粒的强度影响研究

以城市污泥、建筑弃土等固废烧制陶粒,利用XRD、MIP孔结构和SEM等测试手段研究城市污泥对陶粒强度影响。结果表明:通过正交试验获得较优的烧结制度,烧制出污泥掺量为20%的轻质高强陶粒;污泥掺量及对应陶粒氧化物含量(SiO₂及Al₂O₃)均影响陶粒强度;陶粒内部结构随着污泥掺量的增加而变得疏松,污泥掺量为20%的陶粒较掺量为5%的陶粒孔隙率大3.9%以上,陶粒孔径也随着污泥掺量的增加而增大,进而影响陶粒强度;对于氧化物,Al₂O₃含量是影响陶粒强度的主要因素,当其含量超过20.5%以后,陶粒主晶相由石英相逐渐转变为蓝晶石,对陶粒强度提升明显。     

引江补汉工程段中分层减压控制闸布置与体型研究

引江补汉工程段中控制方案将控制闸设置在 164?km 处,以避免局部段内压过高的问题,主要从水动力特性的角度论证洞线总体布置及控制闸布置与体型的合理性。采用一、三维数学模型与物理模型相结合的复合模型开展相关研究：一维水锤数学模型用于闸门启闭过程的全线水力过渡过程分析,通过优化计算,得到相对较优的闸门启闭过程,同时为控制闸段的三维数模与物理模型提供边界条件;三维水气两相流数学模型与物理模型模拟分析闸室与调流池流态与水面波动、中孔溢流面压力分布等水力指标,同时为一维数学模型提供控制闸泄流能力曲线。结果表明：当控制中孔弧形门以先慢后快的三阶段变速率过程开启时,可将全线的最大水锤压力压值在规程允许范围内;中孔溢流面压力分布正常,调流池内水体消能充分,下有压洞进口前沿水面波动较小,未见吸气旋涡等不利流态。引江补汉工程工程采用段中分层减压控制的总体方案是可行的,控制闸布置与体型合理,研究方法可供类似工程参考。     

Measurement Geometry and Hydrostatic Pressure-Dependent Magnetoresistance in All-Oxide-Based Synthetic Antiferromagnets

The electronic structure of constituent layers and the spin channel of propagating electrons are critical factors that affect the magnitude and sign of magnetoresistance (MR) in synthetic antiferromagnets (SAFMs), which are important for spintronic applications. However, for all-oxide-based SAFMs, where there is strong coupling between multiple degrees of freedom, spin transport becomes more complex and remains elusive. Here, using ultrathin half-metallic manganite/doped ruthenate SAFMs as a model system, three sign reversals of MR are demonstrated accompanied by the crossover between underlying spin-dependent transport mechanisms. Electron tunneling produces normal MR in the current-perpendicular-to-plane (CPP) geometry at low temperatures, whereas carrier confinement causes inverse MR in the current-in-plane (CIP) geometry. Strikingly, CPP MR can undergo a temperature-driven sign reversal due to resonant tunneling via localized states in the spacer. Moreover, hydrostatic pressure can modulate the interlayer exchange coupling and induce an asymmetric interfacial response to dramatically facilitate electron tunneling, driving a controllable sign reversal of CIP MR. These results provide new insights into understanding and optimization of MR in all-oxide-based SAFMs.     

大米表面颜色与碾削程度的相关性分析

以两优6393、蓉优3号、益禾8号3种稻谷为试验材料,研究大米表面颜色与糙出白率的关系。垄谷后,对每种糙米进行15、30、45、60和90 s的碾削,得到不同碾削程度的大米样本,测定出每个样本的糙出白率、明度(L)、红绿色调(a)和黄蓝色调(b)值,分析大米颜色特征随碾削时间的变化关系,通过回归分析的方法,分别建立大米表面明度(L)值、红绿色调(a)值和黄蓝色调(b)值与糙出白率关系的模型。结果显示,随着碾削时间的延长,大米的糙出白率显著降低,大米的表面明度明显增大,而红绿色调和黄蓝色调则逐渐减小;随着糙出白率的减少,大米表面的明度线性增大,红绿色调值和黄蓝色调值则线性降低;大米表面的L、a和b值与糙出白率的关系可以描述为简单的线性函数式。     

建构360度师德考核法推进高校师德建设

高校教师职业道德的现状,在主流上是好的,同时,也出现了高校教师职业道德缺失的现象.关键原因是高校缺乏公正、虾侠淼牟僮餍郧康氖Φ驴己朔椒?本文以360度师德考核法为着力点,来解决高校师德中面临的问题.由于360度师德考核具有客观、公正的优良的实践品质和注重考核结果运用的特性,因此在高校师德建设中发挥着独特的作用.     

基于主成分和二维差示扫描量热法分析掺假油菜蜜

结合主成分分析和二维相关分析方法深入挖掘掺假油菜蜜在30~100℃温度范围的差示扫描量热(differential scanning calorimetry,DSC)曲线,揭示该温度范围掺假对油菜蜜的影响。结果表明,温度微扰下的二维DSC相关谱图和主成分分析结果能相互印证,都能深入揭示原始曲线内含的细节信息。掺假对DSC分析中热流率的影响总体是不规则表现。前者在呈现不规则表现的特点上更为直观,后者则能呈现隐藏着的微弱规律。两者结合可用来深入分析掺假油菜蜜样本的DSC特性。