基于FLAC^3D的岩土边坡施工效应研究

采用FLAC3D对预应力锚索框架梁支护的岩土边坡施工过程进行数值模拟,围绕施工中坡体位移场与应力场的变化以及下级边坡施工对上部已完成的支挡结构受力影响进行研究.结果表明坡体开挖引起的松弛区呈圆弧状,且位移由临空面向坡体内逐渐减小,坡体弹性模量与其变形呈非线性递减关系;预应力锚索框架梁能有效抑制坡体变形,从坡顶到坡脚锚索轴力依次增大,故工程设计中宜对其分别设计,做到“强腰固脚”;下级边坡与上级边坡的支挡结构相互约束,共同承担滑坡推力,形成一种“联合支挡结构”.     

基于位置信息的无线传感网络路由改进

基于位置信息的无线传感器网络如果完全采用无状态的方式路由,在某些拓扑结构中存在数据不可到达的缺陷,即死亡点的问题.针对这一问题,将无线传感器网络抽象为一数学模型,在此模型的基础上,给出了问题的数学描述.经分析,提出了一种基于逃离算法的详细解决方案.对算法的性能从理论上分析得出算法没有环路,是正确可行的,而仿真结果也验证了这一点,算法的时间复杂度为O(n).     

冷兵器时代战争对经济发展的影响——以唐、五代时期华北平原为考察中心

安史之乱爆发,使华北陷入战争的泥潭,特别是安史之乱后期,中央和安史叛军主要在华北一带争夺,这里的经济发展受到了严重的破坏,"人烟断绝,千里萧条".有些学者认为安史乱后,华北经济从此便衰落下去,也有些学者不赞成此说.那么,华北平原是否由于安史战乱而一蹶不振呢?     

火炮身管内孔测量仪自动定心装置设计

介绍了一种用于火炮身管内孔参数测量仪的新型自动定心装置设计,给出了这种定心装置的设计思想、工作原理和所达到的定心精度.     

多帧高斯混合概率假设密度的多目标跟踪算法

针对低检测概率下多目标跟踪时,概率假设密度滤波器难以正确估计当前目标个数以及目标状态问题,提出一种基于多帧融合的高斯混合概率假设密度滤波算法。根据不同时刻目标权值构造目标多帧权值记录集及目标状态抽取标志。当某些时刻目标被漏检时,依据目标状态抽取标志,并结合目标多帧权值记录集中权值信息估计丢失目标的状态。仿真实验表明,算法有效地提高了低检测概率下现有相关算法的目标状态和数目估计精度。     

信息化战场下军事指挥决策的人机交互技术与方式研究

人机交互环境是影响信息化战场下军事指挥决策能力与效率的一个重要因素。文章分析了未来信息化战场军事指挥决策面临的挑战,对军事指挥决策人机交互技术与方式的理论、技术与实践进行了深入探讨,研究了我军军事指挥决策人机交互技术与方式的发展思路和方向,提出了信息时代提升我军军事指挥决策能力的建议和对策。     

基于自适应原理的传感器增益故障诊断方法

基于自适应原理提出一种传感器增益故障诊断方法。首先将传感器增益故障表示为传感器偏差故障,再将其表示为执行机构故障,利用自适应原理估计出传感器偏差故障幅度,最后用最小二乘法估计出增益故障幅度。分别对有、无系统噪声和模型误差的情况进行了讨论,最后给出仿真结果     

Market entry strategy in the presence of market spillovers and efficiency differentiation

Firms form various alliances or use brand extensions to enter new markets in order to improve their operational efficiency and create a positive spillover. However, they do not always know the implications of these strategies for market entry and multimarket competition because the sale of products in one market can have negative spillover effects on product sales in other markets. We present an analytical framework to examine whether and how (i.e., by choosing alliance entry or independent entry) competing firms should enter a market in a situation where market spillovers occur when a firm enters a spillover-producing market to sell products that may increase or decrease the consumers' willingness to pay for products in the primary market. Our analysis shows that the operational efficiency (or quality differentiation ability) of firms in a spillover-producing market varies, and hence, the impact of market spillovers differs for firms. We identify the key factors, such as bargaining power, brand value difference in the primary market, and the extent of efficiencies and spillovers, that determine the firms benefitting from the different entry strategies. Specifically, we show that firms would be more willing to choose an alliance strategy to enter a spillover-producing market if the negative spillover is small and alliance efficiency is high. In contrast, if an alliance entry is not favored, the firms' relative operational efficiency is crucial for them to decide whether to enter the market independently under moderate spillover conditions. Finally, we show the implications of market entry strategies for managers.     

新型教学模式下教学路径探讨——基于本科教育“四个回归”

实现本科教育的“四个回归”,是新时代背景下高等本科教育教学改革应该完成的目标。要围绕学生的主体地位来建构新型教学模式下教学路径中的学生角色。学生刻苦学习是学生主体学习地位的基础,实行一定比例的淘汰制是学生刻苦学习的重要保证,助力实现“回归常识”。在教师主导课程学习的过程中,要以学生究竟能学到什么和事实上学到什么作为衡量教学效果的标准,助力实现“回归本分”。课程全过程评价方式是动态全方面的评价方式,改变了目的性极强的单一期末考试评价机制,打破了期末考试一考定成绩的传统做法,助力实现“回归初心”和“回归梦想”。     

Strategic dynamic sourcing from competing suppliers with transferable capacity investment

We study the supplier relationship choice for a buyer that invests in transferable capacity operated by a supplier. With a long‐term relationship, the buyer commits to source from a supplier over a long period of time. With a short‐term relationship, the buyer leaves open the option of switching to a new supplier in the future. The buyer has incomplete information about a supplies efficiency, and thus uses auctions to select suppliers and determine the contracts. In addition, the buyer faces uncertain demand for the product. A long‐term relationship may be beneficial for the buyer because it motivates more aggressive bidding at the beginning, resulting a lower initial price. A short‐term relationship may be advantageous because it allows switching, with capacity transfer at some cost, to a more efficient supplier in the future. We find that there exists a critical level of the switching cost above which a long‐term relationship is better for the buyer than a short‐term relationship. In addition, this critical switching cost decreases with demand uncertainty, implying a long‐term relationship is more favorable for a buyer facing volatile demand. Finally, we find that in a long‐term relationship, capacity can be either higher or lower than in a short‐term relationship. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009