Sorption behavior of thorium(IV) onto activated bentonite

Journal of Radioanalytical and Nuclear Chemistry - Activated bentonite was obtained from acid activation and purification of raw bentonite, sorption of Th(IV) onto activated bentonite was studied...     

Blind restoration of real turbulence-degraded image with complicated backgrounds using anisotropic regularization

This paper proposes a novel blind image restoration method based on estimating the point-spread functions by using two real turbulence-degraded images as input. The non-negative constraint and the spatial correlation are transformed mathematically into the penalty terms and added to the objective function. An anisotropic and nonlinear regularization function is proposed to adequately punish the differences of the point spread functions (PSFs) in the process of optimization estimation. Some definitions of weighted second-order differences are given and a fast method to construct the matrix of second-order weighted gradient operator is derived. The PSF values can be quickly estimated. With the estimated PSFs, the true images can be recovered by non-blind restoration methods. Experiment results for the restoration of real turbulence-degraded images with complicated backgrounds support the effectiveness of this proposed method.     

铁谱图像分析技术的应用研究

本文将计算机图像处理技术应用于铁谱定量分析,对谱片中各单个磨粒的特征参数进行统计,并根据统计模式识别理论设计了4类典型磨粒的分类器。利用统计参数,可以实现磨粒的自动识别分类和统计,大大提高了铁谱定量分析的准确性。     

Stereoselective Electro‐2‐deoxyglycosylation from Glycals

We report a novel and highly stereoselective electro‐2‐deoxyglycosylation from glycals. This method features excellent stereoselectivity, scope, and functional‐group tolerance. This process can also be applied to the modification of a wide range of natural products and drugs. Furthermore, a scalable synthesis of glycosylated podophyllotoxin and a one‐pot trisaccharide synthesis through iterative electroglycosylations were achieved.     

Assessing Markov property in multistate transition models with applications to credit risk modeling

Multistate transition models are increasingly used in credit risk applications as they allow us to quantify the evolution of the process among different states. If the process is Markov, analysis and prediction are substantially simpler, so analysts would like to use these models if they are applicable. In this paper, we develop a procedure for assessing the Markov hypothesis and discuss different ways of implementing the test procedure. One issue when sample size is large is that the statistical test procedures will detect even small deviations from the Markov model when these differences are not of practical interest. To address this problem, we propose an approach to formulate and test the null hypothesis of “weak non‐Markov.” The situation where the transition probabilities are heterogeneous is also examined, and approaches to accommodate this case are indicated. Simulation studies are used extensively to study the properties of the procedures, and two applications are to illustrate the results.     

新(2+1)-维超可积系统的生成

本文利用二项式残数表示方法生成(2+1)-维超可积系统. 由这些系统得到了一个新的(2+1)-维超孤子族,它能约化为(2+1)-维超非线性Schrodinger方程. 特别地,我们得到两个具有重要物理应用的结果,一个是(2+1)-维超可积耦合方程,另一个是(2+1)-维的扩散方程. 最后借助超迹恒等式给出了新(2+1)-维超可积系统的Hamilton结构.     

JEMS-FDTD软件在飞机HIRF仿真中的应用

高强辐射场防护逐渐受到重视,并成为飞机设计和机载设备装机的必要条件。将自主研发的大规模并行三维时域全波电磁模拟软件JEMS-FDTD应用于飞机高强辐射场(HIRF)仿真。数值模拟中为保证计算精度,采用了非均匀网格及共形网格技术。根据实验条件,平面波近似与实验条件差异较大,需考虑天线近场效应,故构建了球面波等效源。给出了平面波近似及球面波近似下的仿真结果与实验结果的对比,结果显示,球面波近似与实验结果更加吻合。在完成数值模拟的基础上,采用PFC方法对仿真结果与实验结果的吻合度进行了评估,评估等级与欧盟HIRF-SE项目定级相当。     

磁绝缘线振荡器的自动优化设计

为克服全电磁粒子模拟(PIC)程序不利于优化设计的弱点, 提高高功率微波器件的优化设计水平, 将遗传算法与全电磁粒子模拟算法有机融合, 研制出二维全电磁粒子模拟并行优化程序。据此对高功率微波源器件两个波段的磁绝缘线振荡器（MILO）：C-MILO和L-MILO进行优化设计。在输入功率不变的条件下, 原C-MILO效率为10.8%, 经优化后效率为15.4%; 原L-MILO效率为12.6%, 经优化后效率为17.7%。由此得出, 两类MILO模型经优化后在输入功率基本不变的情况下输出功率和效率都有很大程度的提高, 且模型几何参数合理, 物理图像正确。     

2 MV激光触发多级气体开关结构设计

高功率开关是脉冲功率装置中的重要部件。介绍了2 MV激光触发多级气体开关的设计思路,给出了开关在强光一号装置上的的静态实验和触发实验结果。实验结果表明：开关的性能基本达到设计的要求;开关在低阻抗传输线中进行实验,面临传输电荷量大的问题,传输电荷越大,将导致更多的放电产物,从而使绝缘能力下降,直接影响开关的使用寿命。     

测量1 MA/100 ns脉冲大电流的微分环

强光一号加速器能输出上升沿约100 ns、幅值约2 MA的电流脉冲。实验中通常采用自积分式Rogowski线圈监测负载电流。为与该线圈比对校验,研制了一种快响应、结构简单、抗电磁干扰性能较好的微分环。标定实验给出,微分环测量的响应时间约1.2 ns,频谱响应范围10 kHz~100 MHz,灵敏度为6.1310-11(Vs)/A。其快时间响应将有助于监测与负载物理特性有关的瞬态电流变化。在加速器二极管短路状态对微分环和积分式Rogowski线圈进行了实验比对,数值积分给出的电流波形与后者基本相符,峰值偏差小于10%,表明微分环的设计合理,同时校验了电流测量的可信度。 