单洞双层隧道围岩力学特性分析

单洞双层隧道作为一种新的隧道形式,不同于分离式隧道和连拱式隧道。利用ANSYS对单洞双层隧道和分离式隧道开挖后围岩的情况进行数值模拟,分析开挖后围岩的应力和位移变化情况、塑性区分布和安全系数,通过对比得出：在浅埋情况下两种隧道围岩应力和位移分布基本一致,地表沉降和分离式隧道相当;单洞双层隧道对围岩扰动深度较大,边墙是其薄弱部位,应力松弛明显,水平位移较大,塑性区水平方向分布较大。     

多目标数据关联的多维Lagrangian松驰法

将多目标跟踪中的数据关联问题提成为一个离散最优化问题 ,并采用 L agrangian松驰算法来克服该问题面临的计算困难 ,这是目前多祯多目标测量数据关联研究发展的重要方向。首先将多祯多目标数据关联问题建立为一个带约束的多维分配问题 ;并在维数大于 2时 ,采用 L agrangian松驰算法来松驰约束条件 ,使问题降维为计算上可接受的二维分配问题。     

Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging

In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process, a one month thermal aging test was carried out at 70 C with pre-strain of 0％, 3％, 6％ and 9％, respectively. The low-field 1H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages. The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging. The results showed that with the increase of aging time, the decay rate of transverse relaxation curve became faster, the transverse relaxation time decreased, the value of combined parameter qMrl increased, the proportion of crosslinking chain decreased, while the proportion of dangling chain increased. Moreover, the stress relaxation modulus increased, the crosslinking network structure of HTPB coating became denser and the degree of cross-linking increased. At the initial aging stage, the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent. With the increase of aging time, the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase. The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950, which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.     

高速核在高温热平衡等离子体中的非平衡弛豫过程对热核反应率参数的影响

高速核入射到高温热平衡等离子体背景中,由于入射核动能远大于背景等离体中带电粒子之平均动能,入射核在与背景等离子体达到热平衡之前,会存在一段逐渐损失能量的非平衡弛豫过程。本文以高速氘核入射到高温氘化锂等离子体为例,在计及氘核的这种非平衡弛豫过程时,给出了一种计算热核反应D(t,n)~4He之反应率参数的方法。氘核在弛豫过程中的能量损失考虑了氘核与各种带电粒子的库仑散射过程,其能量损失率采用快速带电粒子的慢化理论来计算;氘与背景等离子体中的原子核发生的核反应过程,考虑了非平衡状态下束靶机制的D(t,n)~4He反应和热平衡状态下的D(t.n)~4He反应。在暂未考虑核散射的情况下,计算结果表明,当等离子体温度在7.5KeV～20KeV范围内变化时,氘核的非平衡弛豫过程对热平衡状态下D(t,n)~4He反应率参数的修正因子大致在1.0062～1.0943范围内变动,且温度越高,修正因子越小。计算还表明,当温度一定时,修正因子随等离子体中粒子的数密度变化不明显。     

多输入多输出雷达恒模稳健波形联合优化算法

针对目标冲激响应及杂波冲激响应分布特性先验知识不准确导致的多输入多输出雷达检测性能下降的问题,提出恒模稳健波形与接收机滤波器联合优化算法。将目标冲激响应及杂波冲激响应分布特性先验知识不准确时的优化问题建模为一个极大极小化问题。运用迭代优化算法将联合优化问题分解为两个子优化步骤:将波形固定时的接收机滤波器权值优化问题建模为广义瑞利商模型,求解得到相应的接收机滤波器权值矢量;利用半正定松弛技术对权值固定时的波形优化问题进行求解,获得对应的波形矩阵,并根据得到的波形矩阵,通过高斯随机化的方法获得所需的恒模波形。对所提算法的收敛性进行了证明,仿真结果表明所提算法有效。     

Optimal patrol to uncover threats in time when detection is imperfect

Consider a patrol problem, where a patroller traverses a graph through edges to detect potential attacks at nodes. An attack takes a random amount of time to complete. The patroller takes one time unit to move to and inspect an adjacent node, and will detect an ongoing attack with some probability. If an attack completes before it is detected, a cost is incurred. The attack time distribution, the cost due to a successful attack, and the detection probability all depend on the attack node. The patroller seeks a patrol policy that minimizes the expected cost incurred when, and if, an attack eventually happens. We consider two cases. A random attacker chooses where to attack according to predetermined probabilities, while a strategic attacker chooses where to attack to incur the maximal expected cost. In each case, computing the optimal solution, although possible, quickly becomes intractable for problems of practical sizes. Our main contribution is to develop efficient index policies—based on Lagrangian relaxation methodology, and also on approximate dynamic programming—which typically achieve within 1% of optimality with computation time orders of magnitude less than what is required to compute the optimal policy for problems of practical sizes. © 2014 Wiley Periodicals, Inc. Naval Research Logistics, 61: 557–576, 2014     

线性规划的一种并行修正松弛算法

对求解线性规划问题的松弛算法进行了修正,在此基础上提出了一种基于cluster结构的并行算法,分析了算法的性能;基于曙光3000大规模并行计算机,给出了算法用于求解线性规划问题实例的实验结果.理论分析和实验结果表明,修正算法改进了松弛算法的实际性能,同时具有较好的并行性和稳定性,可用于求解此类大规模科学与工程规划问题的高性能计算.     

A combination of Lagrangian relaxation and column generation for order batching in steelmaking and continuous‐casting production

This article considers the order batching problem in steelmaking and continuous‐casting production. The problem is to jointly specify the slabs needed to satisfy each customer order and group all the slabs of different customer orders into production batches. A novel mixed integer programming model is formulated for the problem. Through relaxing the order assignment constraints, a Lagrangian relaxation model is then obtained. By exploiting the relationship between Lagrangian relaxation and column generation, we develop a combined algorithm that contains nested double loops. At the inner loop, the subgradient method is applied for approximating the Lagrangian dual problem and pricing out columns of the master problem corresponding to the linear dual form of the Lagrangian dual problem. At the outer loop, column generation is employed to solve the master problem exactly and adjust Lagrangian multipliers. Computational experiments are carried out using real data collected from a large steel company, as well as on large‐scaled problem instances randomly generated. The results demonstrate that the combined algorithm can obtain tighter lower bound and higher quality solution within an acceptable computation time as compared to the conventional Lagrangian relaxation algorithm. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

听力教学中“环境训练法”的实验研究

本文就学生在听力技能训练中普遍存在较为突出的问题:大脑疲劳与精神紧张,从心理学和生理学的角度提出了"环境训练法".其目的是通过放松练习来改善大脑环境从而使学生在轻松愉快的状态下积极高效地练习听力.通过实验对比与分析,实验组与对照组相比p<0.01,实验组听力成绩明显优于对照组.实验研究证明这一方法具有实用性与有效性.     

一种电阻-时间变换器及应用

以张弛振荡器为基础,提出了一种用电阻-时间变换电路将所测信号转化为量化时间的信号检测新方法。分析表明,该变换器电阻变化与输出时间呈线性关系,电路误差小、抗干扰,调理简单,给出了应用这种电阻时间变换器进行多路检测的单片机系统实例。