Moderate deviations and Erdös-Rényi-Shepp laws for weighted sums

Let X₀,X₁,… be i.i.d. random variables with E(X₀)=0, E(X²₀)=1 and E(exp{tX₀})<∞ for any |t|<t₀. We prove that the weighted sums V(n)=∑_j=0^∞a_j(n)X_j, n?1 obey a moderately large deviation principle if the weights satisfy certain regularity conditions. Then we prove a new version of the Erdös-Rényi-Shepp laws for the weighted sums.     

Asymptotic behaviors for functionals of random dynamical systems

In this article, we consider asymptotic behaviors for functionals of dynamical systems with small random perturbations. First, we present a deviation inequality for Gaussian approximation of dynamical systems with small random perturbations under Hölder norms and establish the moderate deviation principle and the central limit theorem for the dynamical systems by the deviation inequality. Then, applying these results to forward-backward stochastic differential equations and diffusions in small time intervals, combining the delta method in large deviations, we give a moderate deviation principle for solutions of forward-backward stochastic differential equations with small random perturbations, and obtain the central limit theorem, the moderate deviation principle and the iterated logarithm law for functionals of diffusions in small time intervals.     

Geometry-Sensitive Ensemble Mean Based on Wasserstein Barycenters: Proof-of-Concept on Cloud Simulations

An ensemble of forecasts generated by different model simulations provides rich information for meteorologists about impending weather such as precipitating clouds. One major form of forecasts presents cloud images created by multiple ensemble members. Common features identified from these images are often used as the consensus prediction of the entire ensemble, while the variation among the images indicates forecast uncertainty. However, the large number of images and the possibly tremendous extent of dissimilarity between them pose cognitive challenges for decision making. In this article, we develop novel methods for summarizing an ensemble of forecasts represented by cloud images and call them collectively the Geometry-Sensitive Ensemble Mean (GEM) toolkit. Conventional pixel-wise or feature-based averaging either loses interesting geometry information or focuses narrowly on some pre-chosen characteristics of the clouds to be forecasted. In GEM, we represent a cloud simulation by a Gaussian mixture model, which captures cloud shapes effectively without making special assumptions. Furthermore, using a state-of-the-art optimization algorithm, we compute the Wasserstein barycenter for a set of distributional entities, which can be considered as the consensus mean or centroid under the Wasserstein metric. Experimental results on two sets of ensemble simulated images are provided. Supplemental materials for the article are available online.     

锂离子电池聚阴离子型正极材料

聚阴离子型正极材料具有高安全性、低成本和环境友好等优点,是最具潜力的车用动力锂离子电池正极材料之一,但是较低的电子电导率和离子电导率以及较差的倍率性能和低温性能限制了这类材料的实际应用。近年来,通过对材料进行表面包覆电子良导体、体相掺杂以及制备纳米尺寸材料等,显著提升了部分聚阴离子型正极材料的电化学性能;同时,还实现了磷酸亚铁锂在车用动力电池中的实际应用。本文论述了近年来聚阴离子型正极材料研究领域中的研究热点及进展,特别是近几年重新成为研究热点的硅酸盐和硫酸盐正极材料,重点讨论了各种聚阴离子型正极材料的晶体结构、合成及改性方法、电化学性质、安全性以及实际应用所面临的技术瓶颈等,最后探讨了提升材料性能的可能途径。     

Enhanced Conductivity and Antibacterial Behavior of Cotton via the Electroless Deposition of Silver

In this study, the surface-initiated atom transfer radical polymerization (SI-ATRP) technique and electroless deposition of silver (Ag) were used to prepare a novel multi-functional cotton (Cotton-Ag), possessing both conductive and antibacterial behaviors. It was found that the optimal electroless deposition time was 20 min for a weight gain of 40.4%. The physical and chemical properties of Cotton-Ag were investigated. It was found that Cotton-Ag was conductive and showed much lower electrical resistance, compared to the pristine cotton. The antibacterial properties of Cotton-Ag were also explored, and high antibacterial activity against both Escherichia coli and Staphylococcus aureus was observed.     

Synthesis and Characterization of Nano‐Ziconium Dioxide in Recombination Surfactant Association System

This article investigates the influence factors of reagent ratio, pH, stirring intensity, sintering temperature along with ultrasonic wave to particle size, distribution of nanoziconium dioxide in recombination surfactant system. The optimized reagent ratio (wt) of cyclohexan, OP‐10, n‐Amyl alcohol, zircon salt solution are 55%, 17.5%, 17.5%, 10%, respectively. At pH=8.7, the size of nanozirconium oxide has the priority of smaller (<10 nm), narrower particle size distribution and better performance in W/O form.     

电磁场中变厚度载流圆板的非线问题

本文建立了在非定常电磁场和机械场作用下变厚度载流弹性圆板在非线性变形状态下的磁弹性二维关系方程和运动方程，给出了弹性圆板在轴对称条件下的数值解．     

Markov过程的一致中偏差──离散参数情形

本文证明：离散参数Ｍａｒｋｏｖ过程的一致中偏差原理成立的充要条件是Ｄｏｅｂｌｉｎ常返性（即：满足Ｄｏｅｂｌｉｎ条件且是Ｈａｒｒｉｓ常返的）。     

N-Doped carbon dots decorated ceria hollow spheres for enhanced activity of RhB degradation by visible light

The fabrication of low-cost and environmentally friendly photocatalysts with superior photodegradation efficiency remains one of the most pressing challenges in present research. Herein, we elaborately designed and synthesized a promising N-doped carbon quantum dots/CeO₂ hollow microsphere (NCQDs/h-CeO₂) photocatalyst with superior photoresponse property and photoactivity in visible light. The removal efficiencies of rhodamine B (RhB) under visible light illumination for NCQDs/h-CeO₂ exhibits a 30.3% enhancement compared with pure h-CeO₂. The results of EIS and PL imply that the excellent performance may be attributed to the strong synergistic effect between NCQDs and h-CeO_2, thus effectively promoting charge transfer and restraining the recombination of photogenerated holes and electrons. Accordingly, a synergistic photocatalysis mechanism was proposed to explain the photocatalytic reaction process. Besides, the NCQDs/h-CeO₂ exhibits better cycle stability than common CQDs/h-CeO₂ after a four-cycle photocatalytic test. Therefore, the NCQDs/h-CeO₂ may represent a promising strategy for the current water pollution issues.     

光电跟踪系统的共轴跟踪控制技术研究

为了提高光电跟踪系统的跟踪精度,对其粗跟踪环节的共轴跟踪控制技术进行了研究。介绍了共轴跟踪控制的基本原理,分析了常用非线性卡尔曼滤波算法,并仿真比较了无迹卡尔曼滤波(UKF)和容积卡尔曼滤波(CKF)的位置和速度的预测精度。在此基础上综合UKF和CKF的优点,设计了对延迟的合成位置信号进行处理的双并联滤波器,实现了光电跟踪系统的共轴跟踪控制。利用实测数据仿真实验表明,光电跟踪系统的跟踪精度明显提高。