基于匹配追踪稀疏分解的电能质量扰动检测

根据基于冗余字典的匹配追踪(MP)信号分解思想,提出一种电能质量扰动信号的参数检测与特征波形提取方法。在MP算法的每次迭代中,首先采用快速傅里叶变换(FFT)搜索能量最大的频率成分,然后采用基于离散Gabor原子中心区域的简化内积计算方法获得扰动参数的估计值,并以该估计值作为初始解,采用BFGS算法做局部搜索,进而获得精确匹配参数,并结合基于递归的内积计算确定扰动的起止时刻,最后根据电力信号扰动波形特点,设计合成字典,确定与扰动成分最匹配的波形。对单一和混合电能质量扰动信号的分解实验表明,该方法可以实现扰动参数的快速精确检测,进而有效提取扰动特征波形,并具有较好的抗噪性能。     

Assessment of conversion efficiency of Cr4+ ions by aliovalent cation additives in Cr:YAG ceramic for edge cladding

0.25at.% Cr:YAG ceramics were successfully fabricated as the edge cladding of Yb:YAG transparent ceramic slabs through vacuum sintering of co‐precipitated powders, using oxide additives to introduce different cations. The effects of various cation additives (Si⁴⁺, Ca²⁺, and Si⁴⁺ + Ca²⁺) on the conversion efficiency of Cr⁴⁺ ions and optical characteristics of the Cr:YAG edge cladding were investigated. Measurements of the absorption spectra of the Cr:YAG ceramics without any additives revealed 2 absorption bands centered at 430 nm and 600 nm, which imparted the sample with a green color. The introduction of only Si⁴⁺‐bearing additive did not promote the transition of Cr ions from the 3+ to 4+ state. Theoretical analysis and experimentation revealed that the addition of CaO not only enhanced the microstructure and improved the transmittance of the Cr:YAG ceramic, but also introduced vacancies that assisted in the formation of Cr⁴⁺ ions. It was determined that CaO has the same effect on the conversion efficiency of Cr⁴⁺ ions whether it is added as a single additive or in combination with SiO₂. The underlying mechanisms by which these aliovalent cation additives influence the formation of Cr⁴⁺ ions and affect optical properties are discussed in detail. High quality composite ceramics with Yb:YAG transparent ceramic slabs and dark brown‐colored Cr⁴⁺: YAG ceramic edge cladding were achieved through the addition of 0.05 wt.% CaO to the edge cladding, with no interfacial effects between the 2 regions being observed.     

Enhanced Hydrolysis of Cellulose to Reducing Sugars on Kaolinte Clay Activated by Mineral Acid

Catalysis Letters - Kaolinite, a natural, layered phyllosilicate, has been used as the solid catalyst for the hydrolysis of cellulose in our previous work. In the present study, kaolinite was...     

Dy203掺杂(Ba,Sr)TiO3基电容器陶瓷的研究

采用单因素变量法研究了(Ba,Sr)TiO3基电容器陶瓷中掺杂稀土氧化物Dy2O3对材料介电性能的影响,得到了Dy2O3影响其性能的规律,即随着Dy2O3加入量的增加材料的介电常数开始增大随后减少,当W(Dy2O3)=0.5%时介电常数最大,而介质损耗逐渐减少.得到了介电常数为5245,介质损耗为0.0026,耐压为5.5kV/mm的高压低损耗陶瓷电容器瓷料.利用SEM分析了不同Dy2O3加入量样品的表面形貌.结果表明Dy2O3有强烈的偏析晶界、抑制晶粒生长和细晶、形成固溶体等来影响BST性能.这些结果为Dy2O3掺杂改性(Ba,Sr)TiO3基电容器陶瓷提供依据.     

高速逆流色谱法在天然香料单离中的应用

高速逆流色谱(HSCCC)是一种新型的液-液分配色谱分离技术.由于其具有无不可逆吸附等优点,已被广泛应用于各个领域.在简介HSCCC分离流程与策略的基础上,综述了HSCCC在天然香料分离纯化领域中的应用,并展望了HSCCC在该领域的研究及应用前景.     

煤系地层致密砂岩气甜点区地震逐级预测——以鄂尔多斯盆地东南缘下二叠统山西组2~3亚段为例

鄂尔多斯盆地东南部下二叠统山西组2~3亚段(以下简称山2~3亚段)为该盆地重要的天然气勘探目的层,但该亚段储层薄、厚度变化快、非均质性强,储层预测和勘探目标优选难度大。为了准确预测该亚段煤系地层致密砂岩气甜点区、提高天然气勘探成功率,针对该套储层的特征和预测难点,提出了90°相移技术识别河道外形、模型约束波阻抗反演刻画砂体厚度和子波衰减梯度属性识别含气砂体的地震逐级预测技术。研究结果表明:①山2~3亚段上覆5号煤地震强反射层,下伏储层地震反射能量弱,加之为稀疏二维地震测网、井控程度低,致使致密砂岩气甜点区预测难度大;②所提出的技术方法通过地震逐级预测约束,可以有效地刻画河道砂体分布并识别有效含气储层,提高了对勘探开发目标预测的精度;③基于该技术方法指导部署的勘探开发目标实钻效果好,地震预测结果横向分辨率高,真实地反映了河道及河道砂体的变化特征。结论认为,采用该方法可以有效地解决二维地震勘探区煤系地层强非均质性、薄储层致密砂岩气甜点区预测的地质难题。     

提高电网功率因数的研究

本文从理论和实践两方面对电网的功率因数提高及供电电压质量的提高作了深入的研究，并以实例提出了切实可行的解决方法。     

十三陵抽水蓄能机组生产制造工艺

十三陵机组是我公司生产制造的首台抽水蓄能机组，是与ＥＬＩＮ公司合作制造的新产品。本文着重介绍其主要部件及装配的生产制造工艺。     

氮碳化合物超细粉中氧的状态分析

用新开发的热抽取法，测定了超细粉中不同状态氧的含量。应用ＸＰＳ，ＡＥＳ和ＦＴ—ＩＲ表面分析技术鉴定粉末颗粒中氧的物种和分布。探讨了Ｓｉ３Ｎ４，ＡｌＮ，ＴｉＣＮ和ＳｉＣ超细粉中各状态氧含量与样品制备工艺、颗粒度及放置时间的关系。     

N2 adsorption curve of mesoporous SiO2: A neglected characterization technique

Mesoporous SiO₂ sieve and SiO₂ nanoparticles were synthesized by a traditional method in the presence and absence of tri-block copolymer surfactant P123 as structure directed agent respectively. The characterization results show that the mesoporous SiO₂ sieve has larger specific area (789 m²/g) than SiO₂ nanoparticles (373 m²/g), and there exists a substantial difference in the N₂ adsorption curves between the two samples. A speculative scheme shows that the formation of bottleneck during the N₂ adsorption process of mesoporous SiO₂ sieve should be responsible for the phenomenon.