Push和pull两种调度机制的仿真分析与研究

针对当前高性能路由器普遍采用的多级多平面交换结构,对"push"和"pull"这两种最常用的调度机制进行了分析.通过搭建opnet平台对这两种调度机制进行了仿真对比,结果表明,两种调度机制各有优缺点,需要根据实际需求来选择合适的调度机制.     

城市燃气管道喷射火事故后果分析

高压下的城市燃气如果泄露，气体在裂口处被点燃则形成喷射火，对管道周围人员和财产安全造成极大威胁。本文运用喷射火焰对目标的入射热辐射强度计算模型，给出了火灾伤害半径和伤害面积，进而根据城市街区平均人员密度和平均财产密度确定喷射火事故造成的人员伤亡数量和财产损失程度，为城市燃气管道风险评价提供重要的依据。     

Virtual community-based video resource sharing solution in MANETs

The virtual community has emerged as a state-of-the-art technology, grouping the user with the common interest and providing a feasible solution for large-scale deployment of resource sharing services. Efficient sharing for video resources and low maintenance cost of overlay topology are key factors in MP2P video on demand systems. In this paper, a novel virtual community-based video resource sharing (VCVRS) solution in MANETs is proposed. VCVRS design a virtual community construction strategy to group the nodes with the common playback behavior and a flexible community maintenance mechanism so as to obtain the fast supplier discovery and low maintenance overhead. Simulation results show how VCVRS achieves higher lookup success rate, lower server stress, lower node load and less overlay maintenance overhead, in comparison with another state of the art solution.     

适用于柴油HCCI燃烧的碳烟半经验模型研究

将改进的碳烟半经验模型和简化正庚烷的化学反应机理纳入KIVA-3V程序中,以描述柴油燃烧过程中碳烟的生成和氧化历程。通过以正庚烷为燃料的激波管试验验证发现,在较宽的温度和压力范围内,该碳烟半经验模型可以相对准确地预测碳烟的生成率、颗粒直径和数密度。在定容燃烧器中典型的传统柴油机的扩散燃烧和接近于均质压燃(HCCI)发动机的预混燃烧状况下,应用此碳烟模型进一步研究了喷孔直径和喷射压力对碳烟排放的影响。结果发现模型预测得到的碳烟体积分数分布与试验吻合得较好,同时显示当控制局部当量比小于2.0时可以避免碳烟的生成。     

Synthesis and Bacterial Mutagenicity of Oxidized Derivatives of-Polycyclic Aromatic Hydrocarbons

A series of oxidized derivatives of nitrophenanthrene and nitrobenz[a]anthracene were synthesized and their mutagenicities in Salmonella typhimurium TA98, TA98NR, TA98/1,8-DNP₆, TA100, and TA100NR were determined. These compounds exhibited markedly different mutagenicities. Orientation of the nitro group is an important structural feature for correlation with mutagenic potency.     

Effect of sloped die lip geometry on the operability window in slot coating flows using viscocapillary and two-dimensional models

As an indicator for determining the operability window in slot coating flow, the viscocapillary model considering various configurations of upstream and downstream slot die lips was tested and compared with Navier–Stokes two-dimensional model. Bead pressure and sloped lip angle conditions for uniform coating operation demarcated from leaking and bead break-up defects were quantitatively predicted from the position of upstream meniscus from both models. By comparing the results, it is confirmed that the viscocapillary model for many kinds of sloped die lips could predict the operability window accurately. It is also found that there exists vortex or recirculation regimes inside upstream and downstream coating bead regions, depending on the angles of sloped die lips, even for the stable coating flow. The flow control by die lip structure will be usefully applied to design the strategy for the reliable and optimal coating process, including vortex-free windows.     

基于微平面模型的混凝土本构矩阵

在Zdenek P Baant等人提出的微平面模型的基础上,提出了确定混凝土本构矩阵的逐步拟合方法.给出了基于微平面的应力-应变刚度矩阵,并采用逐步拟合法根据试验数据给出了微平面上应力-应变关系函数的量化形式.模型基于单轴试验数据进行拟合,可用于计算材料的多轴本构关系,也可用来进行隐式分析.     

开放网络环境下的程序设计：从RPC到REST

在Internet/WWW这一开放软件平台上已发展了诸多软件架构技术,针对开放网络环境下不同的应用场景与需求,如何对复杂多样的技术进行架构决策、技术选取等提供指导是亟需解决的问题。在考察RPC、Web服务等已有架构、技术的基础上,总结了它们共有的重要方面,分析了这些方面是如何相互交织并影响系统的非功能属性,从而形成一个评估框架。最后,选取典型的技术对其进行比较评估。     

镀钛金刚石制备金刚石聚晶的研究

在国产六面顶高压设备上,以镀钛金刚石为原料,镍基合金为烧结助剂,采用熔渗法成功制备了金刚石聚晶（PCD）,通过扫描电镜（SEM）、X射线衍射（XRD）、拉曼光谱（Raman）等测试方法,研究了不同烧结压力和温度对镀钛金刚石聚晶组织形貌的影响,与普通金刚石聚晶进行了物相成分及残余应力的对比分析。实验结果表明：烧结条件为5.4-5.6GPa,1350℃-1450℃下的镀钛PCD具有较高的致密性和机械性能;镀钛PCD的衍射峰中有NiMnCo、碳化钛和TiMnC化合物。镀钛PCD相比普通的PCD表面残余应力略大。