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排序方式: 共有593条查询结果,搜索用时 15 毫秒
1.
Hechun Cao Hui Zheng Lining Fan Zifeng Cheng Jianwei Zhou Qiong Wu Peng Zheng Liang Zheng Yang Zhang 《International Journal of Applied Ceramic Technology》2020,17(2):813-822
In this study, yttrium iron garnet co-doped with Zn and Zr atoms with a chemical formula Y3ZnxZrxFe(5−2x)O12 (x = 0.0-0.3) has been successfully prepared by the solid-state reaction method. The effects of doping concentration on the microstructure, crystal structure, magnetic properties, and dielectric properties of Y3ZnxZrxFe(5−2x)O12 were investigated. The microstructure analysis indicates that co-doping of YIG with Zn and Zr can effectively reduce the grain size of the ceramic. The crystal structure results reveal that the doping concentration of Zn–Zr has substantial influence on the lattice parameters of YIG, such as, increases the lattice constant, crystal cell size, and interplanar spacing. However, the second phase of ZrO2 appears once x ≥ 0.15. Additionally, the dielectric properties of YIG ferrite can be regulated using this Zn–Zr co-doping method. Zn–Zr co-doping can improve the dielectric stability and reduce the dielectric loss at high temperature. The magnetization measurement shows that the saturation magnetization is stabilized at x < 0.15, and the magnetic loss is decreased with the increase in the doping concentration. Overall, the findings show that the ceramic with x = 0.1 exhibits better properties included high saturation magnetization (24.607 emu/g), low magnetic loss (0.0025 @ 1 MHz), and relatively low dielectric loss (496 @ 400°C). 相似文献
2.
随着我国城市化进程的加快,城市生活污水量急剧增加。污泥作为污水处理后的附属产品,对环境影响极大,因此污泥的无害化、减量化、资源化处理迫在眉睫。燃煤电厂污泥掺烧是实现最大体积减少污泥的处置方法之一。发达国家和地区中,污泥掺烧工艺已逐渐成熟,在燃煤电厂的应用更为广泛。综述了污泥掺烧技术的现状,分析了燃煤电厂掺烧污泥造成的影响,并讨论了燃煤电厂污泥掺烧技术的未来发展方向。 相似文献
3.
钠离子电池健康状态(SOH)预测对于电池优化管理有重要意义,但由于钠离子电池老化机理复杂,影响因素众多,精准SOH预测挑战巨大.为此,本研究从健康状态时序测量数据出发,提出了基于双指数模型的粒子滤波法(DEM-PF)和基于小波分析的高斯过程回归法(WA-GPR),以实现钠离子电池单步SOH和剩余可用寿命(RUL)预测.前者直接采用双指数函数构建时序SOH数据模型,并结合PF算法进行模型参数更新;后者采用小波分析实现时序SOH数据多尺度解耦,采用GPR构建各尺度数据模型并进行融合后实施预测.实验结果表明,相比DEM-PF方法,WA-GPR方法的单步SOH和RUL预测效果更好,单步SOH预测均方根误差为0.8%,RUL预测误差最小为3次循环,从而为钠离子电池管理提供有效支撑. 相似文献
4.
增设快速频率响应备用容量,为威胁系统频率安全事件设立备用规划方案,是应对电力系统频率稳定新形势的重要手段.首先,考虑一次调频事故拦截的潜在收益,采用风险偏好成本收益分析模型作为小概率极端事件的风险价值评估依据;基于序贯蒙特卡洛方法建立常规机组、高压直流传输线路、风电机组的运行状态模型,并将故障集输入所提的系统频率仿真模型中,对功率扰动实现系统频率追踪及下降最低点捕捉,进而获得满足快速频率响应备用容量;兼顾可靠性收益与备用综合成本,定义快速频率响应备用成本收益模型,并提出相应的备用方案可行性校验方法.算例结果表明:所提快速频率响应备用容量规划方案能有效的避免小概率极端事件被同质化,且极端事件概率越小,备用需求越高. 相似文献
5.
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7.
Ma Xuedan Guo Daishi Jiang Qizhong Ma Zifeng Ma Zhengfei Ye Weidong Li Chunbo 《Frontiers of Chemical Engineering in China》2007,1(1):45-49
Nanosized solid superacids SO4
2−/TiO2 and S2O8
2−/TiO2, as well as MCM-41-supported SO4
2−/ZrO2, were prepared. Their structures, acidities, and catalytic activities were investigated and compared using XRD, N2 adsorption-desorption, and in situ FTIR-pyridine adsorption, as well as an evaluation reaction with pseudoionone cyclization. The results showed that SO4
2−/TiO2 and S2O8
2−/TiO2 possess not only nanosized particles with diameters < 7.0 nm, a BET surface greater than 140 cm2/g and relatively regular mesostructures with pores around 4.0 nm, but also a pure anatase phase and strong acidity. Different
from the Lewis acid nature of SO4
2−/ZrO2/MCM-41, SO4
2−/TiO2 and S2O8
2−/TiO2 exhibit mainly Bronsted acidities. The strongest Bronsted acid sites were produced on SO4
2−/TiO2 promoted with H2SO4, while Lewis acid sites on S2O8
2−/TiO2 even stronger than those on SO4
2−/ZrO2/MCM-41 were generated when persulfate solution was used as sulfating agent. Because of their distinct acid natures, SO4
2−/TiO2 and S2O8
2−/TiO2 exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO4
2−/ZrO2/MCM-41. It can be concluded that the existence of more Br?nsted acid sites was favorable for proton participation in the
cyclization reaction.
Translated from Journal of Chemical Engineering of Chinese Universities, 2006, 20(2): 239–244 [译自: 高校化学工程学报] 相似文献
8.
Jadoon Habib Ullah Khan Huang Deqing Qin Na Gong Zifeng 《International Journal of Control, Automation and Systems》2021,19(8):2769-2783
International Journal of Control, Automation and Systems - The fault and disturbances estimation has an important role in the modern traction railway system. This paper proposes a unique method for... 相似文献
9.
在全钢载重子午线轮胎胎面胶中直接添加5~15份杜仲橡胶或用杜仲橡胶等量替代天然橡胶(NR),研究其对胎面胶性能的影响。结果表明:在胎面胶中直接添加杜仲橡胶,胶料的门尼粘度增大,门尼焦烧时间略有延长;且随着杜仲橡胶用量的增大,t90略有延长,Fmax-FL呈减小趋势,硫化胶的邵尔A型硬度、100%定伸应力和300%定伸应力呈减小趋势,抗切割指数先减小后增大,拉伸强度和回弹值变化不大,拉断伸长率呈增大趋势,胶料0和25 ℃时的损耗因子(tanδ)先增大后减小,但均大于未添加杜仲橡胶的胶料,60 ℃时的tanδ变化不大;将杜仲橡胶等量替代NR,随着杜仲橡胶用量的增大,胶料的门尼粘度呈增大趋势,t90基本呈延长趋势,Fmax-FL先增大后减小,硫化胶的硬度、100%定伸应力、300%定伸应力呈减小趋势,拉断伸长率、回弹值、DIN磨耗指数和抗切割指数呈增大趋势,拉伸强度变化较小,胶料0 ℃时的tanδ增大,60 ℃时的tanδ减小,表明胶料的抗湿滑性能提高,滚动阻力下降。 相似文献
10.
Xiaolei Li Zifeng Lin Na Jin Lei Sun Xiaojiao Yang Ying Liu 《Advanced functional materials》2023,33(20):2214667
Polyoxometalates are intriguing high-capacity anode materials for alkali-metal-ion storage due to their multi-electron redox capabilities and flexible structure. However, their poor electrical conductivity and high working voltage severely restrict their practical application. Herein, the dinuclear polyoxovanadate Sr2V2O7·H2O with unusually high electrical conductivity is reported as a promising anode material for lithium-ion batteries. During the initial lithiation process, the Sr2V2O7·H2O anode experiences an electrochemically induced crystalline-to-amorphous transition. The resulting amorphous structure provides high redox activity and fast reaction kinetics via reversible V4.9+/V2.8+ redox couple through the intercalation mechanism. Furthermore, when coupled with the LiFePO4 cathode, the strong V O bonds of the amorphous anode provide excellent structural stability, with the full-cell capable of performing >12 000 cycles with a capacity retention of 72%. Another advantage of Sr2xV2O7-δ·yH2O (0.5 ≤ x ≤ 1.0) is its composition adjustability, which enables delicately regulating the Sr vacancy content without destroying the structure. The defect Sr2xV2O7-δ·yH2O (x = 0.5) electrodes show significantly improved specific capacity and rate capability without sacrificing other key properties, delivering a high specific capacity of 479 mAh g-1 at 0.1 mA cm-2 and 41.9% of its capacity in 2 min. Overall, the preliminary study points the way forward for the facile preparation of high-quality polyoxometalates for advanced energy storage applications and beyond. 相似文献