基于电压曲线特征的电压暂降凹陷域快速计算

针对现有的电压暂降凹陷域计算方法进行了分析研究,提出一种基于敏感负荷节点电压曲线特征的凹陷域快速计算方法.当线路发生单相接地故障时,分析敏感负荷节点电压的表达式,在此基础上定义了由节点阻抗矩阵元素组成的一致性参数和单调性参数,用来判断电压曲线是否具有单调性.根据电压曲线单调与否,把线路分为两类,采用不同的临界故障点计算方法.以IEEE 39节点标准测试系统为例,分析敏感负荷节点的凹陷域.并与已有的解析式法对比,结果表明,该算法在保证精确度的前提下提高了计算速度.     

强震区土石坝筑坝材料动力特性试验研究(投稿研究生论坛)

土石坝筑坝材料的动力特性是进行坝工设计和动力评价的基础。以西部强震区某土石坝工程为研究对象,采用室内动三轴试验,对其坝壳料、心墙料和坝基断层料进行动力特性试验研究,并以Hardin-Drnevich模型为基础,确定筑坝材料的动弹模、阻尼比等特性参数,试验表明：在动应变在10-6 ～ 10-5 范围内,动模量与围压、固结比成正相关;随动模量的增大,相关性降低;动应变和振级的拟合指数模型则表明不同围压、固结比的心墙料的应变-振级曲线趋势一致,坝壳料较为离散;试验中固结围压对粗骨料阻尼比-应变曲线的影响较固结比大,可为强震区土石坝的动力稳定评价提供可靠的理论依据。     

丁苯透明抗冲树脂的合成和性能

以苯乙烯、丁二烯为单体，Ｓ－ＢｕＬｉ为引发剂，环己烷为溶剂，烷氧基硅烷为偶联剂，通过负离子聚合和偶合反应，再经化学处理而制得了具有星形嵌段结构的两个牌号丁苯透明抗冲树脂ＬｙＢＤＳ－０１，ＬｙＢＤＳ－０３。试验考察了聚合温度对反应速率的影响，单体配比，共聚物结构与树脂性能的关系，测试结果表明，ＬｙＢＤＳ－０３的伸长率约为ＬｙＢＤＳ－０１的１０倍，冲击强度约大１倍，硬度小于ＬｙＢＤＳ－０１。两个牌号树     

我国典型地区大气腐蚀性的综合评价

运用模糊综合评价方法,选择合适的隶属函数,根据国际标准化组织ISO9223大气腐蚀性评价分级标准和我国大气腐蚀网站的腐蚀数据,对我国典型地区的大气腐蚀性进行了综合评价,其结果与单因素评价进行了对比。综合评价结果能较好地反映我国典型地区大气环境的腐蚀性。     

Gd0.8Sr0.2CoO3阴极的甘氨酸-硝酸盐法制备及性能研究

为探索适于中温条件下使用的固体氧化物燃料电池的阴极材料,用甘氨酸-硝酸盐法(GNP法)制备了Gd0.8Sr0.2CoO3(GSC)阴极粉体,用X-ray衍射考察了GSC的成相温度.采用丝网印刷法将GSC沉积在(Sm2O3)0.2(CeO2)0.8(SDC)圆片上,制成对称阴极,在不同温度下烧结.用交流阻抗谱从500℃到750℃测量了GSC阴极和SDC电解质之间的界面电阻.结果表明,用甘氨酸-硝酸盐法制备的GSC粉体的成相温度比传统固相法降低了400℃～500℃;700℃时,GSC阴极的界面电阻仅为0.26 Ω·cm2.     

(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3-Co0.85Cu0.15Fe2O4复合陶瓷的磁电性能研究

以压电体(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3和压磁体Co0.85Cu0.15Fe2O4为原料,通过传统的固相反应法制备了(1-x)[(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3]-xCo0.85Cu0.15Fe2O4多铁性复合陶瓷,并使用X射线衍射仪、扫描电子显微镜、压电测试仪、铁电测试仪和磁电耦合测试仪对物相、显微结构、压电、铁电、磁电耦合性能进行了分析。结果表明,复合陶瓷的相结构保持为(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3和Co0.85Cu0.15Fe2O4两种物相,但两者之间发生了轻微的化学反应。随着Co0.85Cu0.15Fe2O4压磁相含量的增加,复合陶瓷的压电系数从56pC/N减小到21pC/N,剩余极化强度略有降低。在压磁相含量为0.2时可获得4.3mV·cm-1·Oe-1的最佳磁电耦合系数。     

Thermodynamic description of the Al-Li-Zn system

The Al-Li-Zn system was critically assessed using the CALPHAD technique. The solution phases (liquid, bcc, fcc and hcp) were described by the substitutional solution model. The compounds Al₂Li₃ and Al₄Li₉ in the Al-Li system had homogeneity ranges of Zn and were treated as (Al,Zn)₂Li₃ and (Al,Zn)₄Li₉ in the Al-Li-Zn system, respectively. The compounds αLi₂Zn₃, βLi₂Zn₃, αLi₂Zn₅, βLi₂Zn₅ and αLiZn₄ in the Li-Zn system had no solubility of the third component Al in the Al-Li-Zn system. A two-sublattice model (Al,Li,Zn)_0.2(Al,Li,Zn)_0.8 was applied to describe the compound βLiZn₄ in the Al-Li-Zn system in order to cope with the order-disorder transition between hexagonal close-packed solution (hcp-A3) and βLiZn₄ with the Mg-type structure. The ternary compound τ₂ with a NaTl-type structure (B32) had the same structure with the compounds AlLi in the binary Al-Li system and LiZn in the binary Li-Zn system. In the present work, the three compounds AlLi, LiZn and τ₂ were treated as one phase by a two-sublattice model (Al,Li,Zn)_0.5(Al,Li,Zn)_0.5 in order to cope with the order-disorder transition between B32(AlLi, LiZn and τ₂) and body-centered cubic solid solution (bcc-A2). The ternary intermetallic compounds τ₁ and τ₃ in the Al-Li-Zn system were treated as the formula Li(Al,Zn)₂ and (AlLi,Zn)Zn₃, respectively. A set of self-consistent thermodynamic parameters describing the Gibbs energy of each individual phase as a function of composition and temperature in the Al-Li-Zn system was obtained.     

小型一体化PLC在气箱式脉冲袋收尘器中的应用

采用HOLLiAS—LEC G3小型一体化PLC对气箱式脉冲袋收尘器的控制系统进行了改造，提高了控制系统的稳定性和灵活性。