低功耗矢量水声信号采集处理系统设计与实现

为进一步降低矢量水听器信号采集处理系统对水下滑翔机平台的续航影响,设计了一种以 ARM和 DSP 为核心控制 器的低功耗信号采集处理系统。利用ARM 控制器实现系统的多种工作模式,以达到不同状态下的最佳功耗控制。此外,在 控制软件中加入必要的优先级设计和流水线设计,以提高系统硬件控制效率,最后利用功率测试仪对系统不同工作模式进行 测试。结果表明,低功耗模式下平均功耗约为1.27 W, 实时处理模式下平均功耗约为4.29 W。 在长时间连续工作情况下,可 大幅度降低实时处理模式的工作时间占比,功耗控制效果显著,有效证明了该方案的有效性和优越性。     

晶界扩散Tb对烧结Nd-Fe-B组织与磁性能的影响

用磁控溅射法在烧结Nd-Fe-B磁体表面沉积Tb金属薄膜并进行晶界扩散处理,对比经不同热扩散温度及时间处理后的磁体组织和磁性能变化.结果 表明,925℃×10 h+500℃×2 h为最佳晶界扩散工艺,可将磁体矫顽力提高到1630.9 kA· m-1,较原始磁体提升50％,同时剩磁和磁能积无明显下降,磁体仍具有较高的退磁...     

Stable sodium metal anode enhanced by advanced electrolytes with SbF3 additive

The practical application of sodium metal batteries (SMBs) is hampered due to the inferior interfacial stability between Na metal and conventional electrolytes....     

Size-controlled MoS<Subscript>2</Subscript> nanodots supported on reduced graphene oxide for hydrogen evolution reaction and sodium-ion batteries

Transition metal dichalcogenide nanodots (NDs) have received considerable interest.We report a facile bottom-up synthetic route for MoS2 NDs by using molybdenum pentachloride and L-cysteine as precursors in oleylamine.The synthesis of NDs with a narrow size distribution ranging from 2.2 to 5.3 nm,was tailored by controlling the reaction time.Because of its coating characteristics,oleyalmine leads to uniformity and monodispersity of the NDs.Moreover,the NDs synthesized have large specific surface areas providing active sites.Graphene possesses outstanding conductivity.Combining the advantages of the two materials,the 0D/2D material exhibits superior electrochemical performance because of the 2D permeable channels for ion adsorption,energy storage,and conversion.The as-prepared MoS2/rGO (～2.2 nm) showed a stable capacity of 220 mAh·g-1 after 10,000 cycles at the current density of 20 A·g-1.Furthermore,a reversible capacity ～140 mAh·g-1 was obtained at a much higher current density of 40 A·g-1.Additionally,this composite exhibited superior catalytic performance evidenced by a small overpotential (222 mV) to afford 10 mA·cm-2,and a small Tafel slope (59.8 mV·decade-1) with good acid-stability.The facile approach may pave the way for the preparation of NDs with these nanostructures for numerous applications.     

多孔高吸水性树脂制备方法及应用研究进展

多孔高吸水性树脂是一种新型的高分子材料,性能优异,用途广泛。综述了多孔高吸水性树脂的的吸水机理及应用,介绍了多孔高吸水性树脂的形成方法,并对其发展前景进行了展望。     

Ca杂质对Na-β″-Al_2O_3在钠硫电池中退化的影响

研究了钠硫电池中 β″-Al_2O_3固体电解质、钠电极和硫电极的 Ca 杂质对 β″-Al_2O_3电性能退化的影响。用电子探针分析检测了电池失效后,β″-Al_2O_3陶瓷管在两个电极之间表面的 Ca 杂质。Ca 杂质主要存在于β″-Al_2O_3的内表面,即在 β″-Al_2O_3/Na 电极界面。试验表明硫电极中的 Ca 杂质(<60 ppm)对钠硫电池电阻随工作循环周次的升高在早期没有影响。在钠硫电池工作过程中,结合 β″-Al_2O_3电解质中的 Ca 杂质最有害于 β″-Al_2O_3的电导及其强度的退化,讨论了电池在充放电过程中 Ca 杂质对 β″-Al_2O_3电阻增加及其损坏的影响机理。     

信号解调的正交滤波器方法

信号的解调分析是通讯领域和机械故障诊断的常用方法。本文从数字滤波器的角度出发,提出了实现信号解调的正交滤波器法,即基于 Ｆ Ｉ Ｒ 正交滤波器方法和基于正交小波函数的正交滤波器方法。正交滤波器方法将带通滤波和希尔伯特变换的过程和功能有合二为一,实现过程方便。针对 Ｆ Ｉ Ｒ 正交滤波器方法的缺点,本文根据函数逼近理论,在理论上,证明了正交小波函数可以最佳一致逼近理想滤波器。并在具体应用上,介绍了采用正交小波函数构造正交滤波器时,参数的选择和信号解调分析的具体实施方法。采用正交小波函数设计的正交滤波器方法,带宽选择方便,相位的线性度高,正交性好,而且滤波器的滤波性能更优。可根据要求很方便地实现多通带信号滤波和多通带信号的解调分析     

Core–Shell Structure and Interaction Mechanism of γ‐MnO2 Coated Sulfur for Improved Lithium‐Sulfur Batteries

Lithium‐sulfur batteries have attracted worldwide interest due to their high theoretical capacity of 1672 mAh g^?1 and low cost. However, the practical applications are hampered by capacity decay, mainly attributed to the polysulfide shuttle. Here, the authors have fabricated a solid core–shell γ‐MnO₂‐coated sulfur nanocomposite through the redox reaction between KMnO₄ and MnSO₄. The multifunctional MnO₂ shell facilitates electron and Li⁺ transport as well as efficiently prevents polysulfide dissolution via physical confinement and chemical interaction. Moreover, the γ‐MnO₂ crystallographic form also provides one‐dimensional (1D) tunnels for the Li⁺ incorporation to alleviate insoluble Li₂S₂/Li₂S deposition at high discharge rate. More importantly, the MnO₂ phase transformation to Mn₃O₄ occurs during the redox reaction between polysulfides and γ‐MnO₂ is first thoroughly investigated. The S@γ‐MnO₂ composite exhibits a good capacity retention of 82% after 300 cycles (0.5 C) and a fade rate of 0.07% per cycle over 600 cycles (1 C). The degradation mechanism can probably be elucidated that the decomposition of the surface Mn₃O₄ phase is the cause of polysulfide dissolution. The recent work thus sheds new light on the hitherto unknown surface interaction mechanism and the degradation mechanism of Li‐S cells.     

Hybrid Perovskite Light‐Emitting Diodes Based on Perovskite Nanocrystals with Organic–Inorganic Mixed Cations

Organic–inorganic hybrid perovskite materials with mixed cations have demonstrated tremendous advances in photovoltaics recently, by showing a significant enhancement of power conversion efficiency and improved perovskite stability. Inspired by this development, this study presents the facile synthesis of mixed‐cation perovskite nanocrystals based on FA_{(1?x )}Cs_x PbBr₃ (FA = CH(NH₂)₂). By detailed characterization of their morphological, optical, and physicochemical properties, it is found that the emission property of the perovskite, FA_{(1?x )}Cs_x PbBr₃, is significantly dependent on the substitution content of the Cs cations in the perovskite composition. These mixed‐cation perovskites are employed as light emitters in light‐emitting diodes (LEDs). With an optimized composition of FA_0.8Cs_0.2PbBr₃, the LEDs exhibit encouraging performance with a highest reported luminance of 55 005 cd m^?2 and a current efficiency of 10.09 cd A^?1. This work provides important instructions on the future compositional optimization of mixed‐cation perovskite for obtaining high‐performance LEDs. The authors believe this work is a new milestone in the development of bright and efficient perovskite LEDs.     

几种江蓠属海藻的ISSR标记分析

用ISSR标记对几种江蓠属海藻进行了遗传多样性的研究。所用的7种实验材料包括4株龙须菜(其中3株分别来自中国青岛、委内瑞拉和南非，及1株青岛产龙须菜的高温选育种)和细基江蓠繁枝变型、真江蓠、芋根江蓠。用9条ISSR引物进行筛选，有6条可扩增出清晰可辨条带。这6条引物在7种材料中共扩增出151条带，其中117条(77．48％)表现出多态性。根据Nei等的遗传相似性系数(S)对7种材料进行分析，结果显示青岛产龙须菜与其选育种的相似性最高(S为0．939)。在3株不同产地龙须菜中，青岛龙须菜与南非龙须菜的遗传距离最近(S为0．643)，委内瑞拉龙须菜与前两者的S分别为0．167和0．192，因此初步推断委内瑞拉龙须菜不属于龙须菜种。包括龙须菜(产自青岛或南非)在内的4种江蓠间的相似性系数在0～0．143之间。