4300/400五叠网多缸涂布白纸板机结构特征

介绍4300/400五叠网多缸涂布白纸板纸机的配置结构及特点.     

弱L-余拓扑空间的可数紧性

紧性是模糊拓扑学中的重要概念.给出了弱L-余拓扑空间中紧性,可数紧性的定义,讨论了可数紧集在L-值Zadeh型函数下的逆不变性,证明了可数紧集与紧集的乘积是可数紧的. 另外, 通过引入具有有限交性质的弱闭集族给出了可数紧空间的一个新特征.     

Jimbo-Miwa方程的对称约化及不变解

基于李群理论利用直接对称法得到了(3 1)-维Jimbo-Miwa方程的对称性.在此基础上,对相应的李代数进行优化,得到了方程的七种相似约化,通过变量分离以及借助辅助函数的方法,对得到的约化方程进行求解,并且得到了方程的一些新的不变解.     

Fine-grained BNT-based lead-free composite ceramics with high energy-storage density

The low breakdown strength of BNT-based dielectric ceramics limits the increase in energy-storage density. In this study, we successfully reduced the sintering temperature of BNT-ST-5AN relaxor ferroelectric ceramics from 1150 to 980 °C by two-phase compounding with nano-SiO₂. Meanwhile, the average grain size of the composite ceramics is also greatly reduced from 4.45 μm to 0.37 μm. Thus, a large recoverable energy-storage density (3.22 J/cm³) is achieved under the ultrahigh breakdown strength (316 kV/cm). Moreover, good temperature (25–150 °C) and frequency (10–200 Hz) stabilities are simultaneously achieved. The excellent energy-storage properties suggest that BNT-ST-based ceramics composited with SiO₂ form a promising low-temperature sintered dielectric material for pulsed power multilayer ceramic capacitors.     

Synthesis and electrochemical properties of nanosized LiFeO2 particles with a layered rocksalt structure for lithium batteries

Layered rocksalt-type LiFeO₂ particles (O3-LiFeO₂) with average particle sizes of ca. 40 and 400 nm were synthesized by an ion exchange reaction from α-NaFeO₂ precursors. X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images confirmed the formation of nanosized O3-LiFeO₂. 40-nm LiFeO₂ exhibited a higher discharge capacity (115 mAh g^?1) than 400-nm LiFeO₂ (80 mAh g^?1), and also had better rate characteristics. The downsizing effect and cation disorder between the lithium and iron layers may have improved the electrochemical activity of the LiFeO₂ particles. Transmission electron microscopy (TEM) observation indicated a phase transition from O3-LiFeO₂ to a cubic lattice system during the electrochemical process. The cubic lithium iron oxide exhibited stable electrochemical reactions based on the Fe²⁺/Fe³⁺ and Fe²⁺/Fe⁰ redox couples at voltages between 4.5 and 1.0 V. The discharge capacities of 40-nm LiFeO₂ were ca. 115, 210, and 390 mAh g^?1 under cutoff voltages of 4.5–2.0 V, 4.5–1.5 V, and 4.5–1.0 V, respectively.     

Pyrochlore free 0.67PMN–0.33PT ceramics prepared by particle-coating method

In present study, pyrochlore-free 0.67Pb(Mg_1/3Nb_2/3)O₃–0.33PbTiO₃ (0.67PMN–0.33PT) powders and ceramics have been successfully prepared. Using oxides as raw materials, pyrochlore-free 0.67PMN–0.33PT powders were obtained by two-step particle-coating method. The XRD and EDS results confirmed that the Mg–citric acid polymeric complex coatings effectively prevent the direct contact between PbO and Nb₂O₅ and thus avoid the formation of pyrochlore phase. The obtained pyrochlore-free 0.67PMN–0.33PT powders at 800 °C showed uniform and even grain size. The 0.67PMN–0.33PT ceramics sintered at 1150 °C for 2 h exhibited 99% of relative density and a piezoelectric coefficient (d₃₃) of 576pC/N, a remnant polarization (P_r) of 28.4 μC/cm², a planar electromechanical coupling factor (k_p) of 0.55 and a mechanical quality factor (Q_m) of 90.     

(2+1)维Gardner方程的对称、约化及其群不变解

利用经典李群方法,得到了一类(2+1)维Gardner方程的显式解,推广了唐和陈勇的某些结果,并且得到了该方程的对称、约化及其群不变解.     

(3+1)-维非线性发展方程新的精确解和守恒律

利用改进的CK直接方法,求出了(3+1)-维非线性发展方程的一般对称群、李对称及其对应的向量场,建立了方程新旧解之间的关系,同时由旧解得到了方程的许多新的精确解.由于对称和守恒律之间有密切的关系,同时找到了此方程的无穷多守恒律.     

CSRZ-DPSK调制信号的PMD补偿性能分析

主要研究新型调制格式CSRZ-DPSK的PMD补偿性能,从理论上推导了CSRZ-DPSK信号的调制原理公式,并给出了实现的具体过程,通过Matlab仿真得到了NRZ、CSRZ、NRZ-DPSK和CSRZ-DPSK的调制信号经过PMD补偿系统前后的DOP值.结果表明,与00K格式相比,DPSK调制格式补偿后的DOP值更多的分布在接近1的范围,其中CSRZ-DPSK具有最好的PMD补偿效果,是实现PMD补偿的首选格式.     

苏通大桥索塔变形自动监测系统的研究

本文介绍了基于测量机器人的索塔变形自动监测系统的组成、定位原理及精度,并分析了苏通大桥索塔施工期的变形情况。试验证明,索塔变形自动监测系统工作可靠,反应灵敏,可以胜任桥梁的自动变形监测工作。