浅水方程大规模并行计算模拟城市洪水演进

基于有限体积法建立求解溃坝水流运动的数学模型,利用Riemann问题求解Godunov格式计算通量,通过空间分块划分的大规模并行计算来加速运算,实现了城市洪水演进的精细数值模拟.数值模拟结果表明,建筑物在溃坝波波前到达初期所受水流荷载最大;受上游建筑物消波、蔽护作用,溃口下游建筑物所受荷载随至溃口的距离的增大而减小,建筑物的存在使得溃坝波在城区传播速度减慢.并行测试表明,缓冲模式比非缓冲模式更适用于浅水方程大规模并行求解.目前大规模并行计算能够实现对面积达400,km2的城区洪水演进进行实时仿真模拟,为滨河、滨海城市在受到溃坝、海啸等洪水威胁时的快速决策和应急疏散提供科学依据.     

Three-dimensional FEM analysis of stress distribution in dynamic maxillary canine movement

An alteration in stress/strain distribution within periodontal ligament (PDL) occurs when the tooth is mechanical stimulated in orthodontic treatment. The majority of previous finite element studies were confined to a static evaluation on initial loading status, and a dynamic long-term analysis was rarely performed in orthodontics. The present study sought to analyze the stress distribution patterns within tooth root, PDL, and alveolar bone during dynamic canine tipping and bodily movement with three-dimensional finite element method in four consecutive therapeutic weeks. We observed that the highest stress was on root surface, secondly alveolar bone, and finally, PDL for either tipping or bodily movement. Throughout the PDL and root surface, the highest stress was always around the cervical area in both patterns of movement through four phases. Moreover, a lower and more uniform stress distribution was produced during bodily movement compared with tipping movement. These results indicated that canine translation might be healthier for periodontal tissue than tipping movement; the cervical region bore a greater load and might also be a susceptible area for tissue damage (except for the apex) regardless of movement pattern.     

带有扩散的两种群时滞生态模型的振动性

对用偏泛函微分方程组所描述的密度分布非均匀的两种群相互作用生态模型进行了讨论 .通过利用时滞泛函微分不等式 ,研究了时滞生态模型的振动性 ,得到了其解关于正平衡态振动的简捷的充分判据 .     

化工专业实验报告撰写改革探索

实验报告是实验操作过程总结以及对获得实验结果分析讨论的书面表达形成。针对传统实验报告存在形式固定和缺乏个性等弊端,在化工专业实验教学中,探索以小论文代替传统实验报告形式的教学改革。实验教学表明,小论文形式的实验报告有助于提供教学质量,对提高学生查阅文献资料和撰写科技论文的能力以及培养学生实事求是的科研态度都起到了积极作用,为大四的毕业论文以及后续的继续学习或科研奠定良好的基础。     

七辊卧式轧机液压系统技术改进

七辊卧式轧机是1995年引进的加拿大二手设备,在国内至今已使用近10年,在这10年期间对机械方面作了大量的修理和更换,但作为轧机重要的控制部分液压控制系统并未改动,频繁出现问题,为了提高轧机运行的稳定性和产品产出,对其系统作了全面改进.     

Effect of cooling rate on the magnetic properties of Fe53Nd37Al10 alloy

The effect of cooling rate on the magnetic properties of the Fe₅₃Nd₃₇Al₁₀ alloy prepared by different methods, i.e., suction casting and melt spinning at different rates, was investigated. The Fe₅₃Nd₃₇Al₁₀ ribbon at the wheel speed of 5 m·s^?1 exhibits the highest coercivity in the samples. Two hard magnetic phases are detected from the hysteresis loops of the 5 m·s^?1 ribbon at all temperatures below room temperature. Their appearance is associated with different exchange coupling interactions, which are between the two kinds of hard magnetic phases or between the hard magnetic phase and the soft magnetic phase.     

模拟微波数字化改造基本方案

介绍了广播电视系统模拟微波进行数字化改造的基本思想，根据不同情况采用SDH、PDH技术进行改造的实施方案。     

工业反哺农业是实现我国农业现代化的必由之路

文章从农业现代化入手,介绍了农业现代化的内涵及特点,指出了中国农业现代化发展的进展及障碍,文章分析了工业反哺农业的内涵,指出工业反哺农业是实现中国农业现代化的必由之路.     

社会转型与道德教育

每当社会转型（即在特定社会时期社会关系，社会制度及社会生活方式的演变）之时，最容易引起人们道德观念的变化，因此，这一时期更应加强度道德教育。     

浅析城市道路沥青路面的养护与施工管理

对路面使用性能作出合理的评价,是路面养护管理系统基本的组成部分.结合太原市的道路实际以路面的各种病害及使用功能作出合理的养护方法.