超强激光场中氘原子电离几率的研究

研究了在相对论领域内,超强激光场的不同条件（频率、强度、脉冲波形磁场分量）对氘原子电离几率的影响,研究表明：电离几率随激光强度的增加而增加,随激光频率的增加而减少。而激光脉冲波形对电离几率的影响仅在激光无磁场分量时比较显著。激光场的磁场分量对原子的电离有一定的影响。     

太赫兹光谱技术用于干旱胁迫下大豆冠层含水量检测研究

近年来水资源短缺问题日益严重,部分地区由于农业灌溉用水不足导致庄稼减产农民利益受损。大豆是一种需水量较大的农作物,一旦水分亏缺将直接影响大豆植株的形态和生长发育,从而造成大豆品质降低和产量减少。大豆叶片的水分状况可真实地反映植株水分受土壤水分亏缺的影响程度,因此,大豆冠层叶片水分含量的快速获取成为一种需要。太赫兹辐射在水中的强烈衰减使其成为一种非常灵敏的非接触式探针,可以快速、无损地检测叶片含水量。因此基于太赫兹光谱这一新技术进行大豆冠层叶片含水量的检测研究,用于实时监测田间大豆的健康状况。实验选用中黄13号大豆进行栽培,为尽可能模拟田间不同程度的干旱胁迫状况,将开花期大豆进行5个不同梯度：正常供水、轻度干旱胁迫、中度干旱胁迫、重度干旱胁迫、严重干旱胁迫(分别占田间最大持水量的80%,65%,50%,35%,20%)的水分灌溉,每个梯度设置3个重复。利用人工称重法与便携式土壤水分速测仪结合将土壤含水量调控到各水分梯度要求。然后,将实验大豆植株运回实验室并利用透射式太赫兹时域光谱仪进行样本扫描,每个梯度采集18片冠层叶片,共90个样本,以2∶1的比例分为校正集和预测集。在获取各样本时域光谱数据后,根据Dorney和Duvillaret提出的模型进行了光学参数的提取,得到各样本的吸收系数谱以及折射率谱。定性分析了太赫兹时域光谱、吸收系数、折射率随水分胁迫程度不同的变化情况。实验发现：随着水分胁迫程度的降低,时域光谱的峰值呈不断衰减趋势,且均低于空白参考峰值,同时有明显的时间延迟。吸收系数值随干旱胁迫程度的加剧逐渐降低;折射率值同样随干旱胁迫程度的加剧逐渐降低。并利用偏最小二乘(PLS)和多元线性回归(MLR)方法定量研究了时域光谱、吸收系数、折射率光谱数据与叶片含水率的相关关系。结果表明,太赫兹波对大豆叶片水分差异十分敏感,基于时域光谱最大值和最小值的MLR预测精度最高,预测集相关性(r_p)达-0.939 3,均方根误差(RMSEP)为0.049 5。研究表明太赫兹光谱技术应用于大豆冠层叶片含水量观测具有良好的可行性,为开展大豆冠层含水量信息快速获取,实现科学节水管理与灌溉决策提供了新的检测手段和实验依据。     

深海直达波区卷积神经网络测距方法

深海声场通常可以看作不同掠射角的多途声线在接收器处的叠加,其中经海底反射的声线携带与海底参数有关的声场特征。利用深度卷积神经网络分别学习垂直阵声压域(CNN-Field)和垂直阵波束域(CNN-CBF)特征的方法被用来估计直达波区声源距离。该方法首先对仿真直达波区声场数据做预处理,然后将声压域和波束域的声场数据分别作为训练集训练深度卷积神经网络模型,最后输入测试集数据到训练完成的模型中估计声源距离.实测环境参数的仿真实验表明CNN-Field方法在不同海底参数的测试集下测距结果差异较大,CNN-CBF方法差异较小,而且在16阵元10 m等间距垂直阵的阵元域信噪比大于0dB时估计准确率可以达到97%.海试数据处理结果表明CNN-CBF方法的直达波区内测距准确率高于CNN-Field,在距离10 km以内的平均准确率可以达到93.16%.     

含一般模糊弹性约束的广义模糊变量线性规划

建立并讨论了一类含有一般模糊弹性约束的广义模糊变量线性规划问题.首先,简单介绍了结构元方法并对结构元加权排序中权函数表征决策者风险态度进行了深入分析.然后选取风险中性的决策者来定义序关系,应用Verdegay模糊线性规划方法将含一般模糊弹性约束的广义模糊变量线性规划转化经典的线性规划问题,简化了原问题的求解.最后通过数值算例进一步说明了该方法的有效性.     

Cramer’s rule over residue class rings of Bézout domains

Cramer’s rule over residue class rings of Bézout domains is given.     

A new formulation of regularized meshless method applied to interior and exterior anisotropic potential problems

This paper proposes a new formulation of regularized meshless method (RMM), which differs from the traditional RMM in that the traditional formulation generates the diagonal elements of influence matrix via null-field integral equations, while our new one directly employs the boundary integral equations at the domain point to evaluate the diagonal elements. We test the present RMM formulation to two-dimensional anisotropic potential problems in finite and infinite domains in comparison with the traditional RMM. Numerical results show that the present RMM sharply outperforms the traditional RMM in the solution of interior problems, while the latter is clearly superior for exterior problems. A rigorous theoretical analysis of circular domain case also corroborates such numerical experiment observations and is provided in the appendix of this paper.     

Design and analysis of a Schwarz coupling method for a dimensionally heterogeneous problem

In the present work, we propose and analyse an efficient iterative coupling method for a dimensionally heterogeneous problem. We consider the case of a 2D Laplace equation with non‐symmetric boundary conditions coupled with a corresponding 1D Laplace equation. We first show how to obtain the 1D model from the 2D one by integration along one direction, by analogy with the link between shallow water equations and the Navier–Stokes system. Then we focus on the design of a Schwarz‐like iterative coupling method. We discuss the choice of boundary conditions at coupling interfaces. We prove the convergence of such algorithms and give some theoretical results related to the choice of the location of the coupling interface, and to the control of the difference between a global 2D reference solution and the 2D coupled solution. These theoretical results are illustrated numerically. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimality theory for semi-infinite linear programming ∗

This paper presents an exhaustive approach to optimality theory in semi-infinite linear programming, placing a special emphasis on generality. After surveying optimality conditions for general problems, a detailed analysis is made of problems in which the coefficients are continuous functions of a parameter which varies on a compact set, adopting a feasible directions approach. Lastly, the case of analytical coefficients over an interval is considered in some detail.