一种调节阀式气体炮建模与分析

为研究气体炮各调整参数对其模拟性能的影响 ,笔者利用气体动力学相似理论的有关知识对双活塞调节阀式气体炮进行了数学建模与分析 ,采用四阶龙格—库塔法的思想进行计算 ,并利用MATLAB语言对其进行编程 ,通过在计算机上运行计算程序 ,得出模拟弹丸的加速度—时间模拟曲线。在对模拟曲线特征进行分析的基础上 ,指出了气体炮各调整参数对弹丸加速度—时间曲线的影响。     

机器翻译中语义块汉英变换处理

首先解释了要素句蜕的内涵,同时介绍了HNC理论的句蜕观,并依据HNC句类理论提出了汉英机器翻译中,要素句蜕处理的具体规则,还结合真实语料进行了验证。     

概念层次网络中对偶性设计

首先对概念层次网络（ＨＮＣ）理论作简要说明,然后根据ＨＮＣ中层符号个性化设计理论给出对偶性设计方案,和偶性的具体表现,并给出对偶性概念具体表现的注解。     

军校的改革在于开放

分析了我军院校发展中存在的问题,提出了培养合格军事人才军校必须采取的措施,阐明了军校教育必须从封闭走向开放,才能在世界军事斗争中处于不败之地。     

Estimating failure time distribution and its parameters based on intermediate data from a Wiener degradation model

Instead of measuring a Wiener degradation or performance process at predetermined time points to track degradation or performance of a product for estimating its lifetime, we propose to obtain the first‐passage times of the process over certain nonfailure thresholds. Based on only these intermediate data, we obtain the uniformly minimum variance unbiased estimator and uniformly most accurate confidence interval for the mean lifetime. For estimating the lifetime distribution function, we propose a modified maximum likelihood estimator and a new estimator and prove that, by increasing the sample size of the intermediate data, these estimators and the above‐mentioned estimator of the mean lifetime can achieve the same levels of accuracy as the estimators assuming one has failure times. Thus, our method of using only intermediate data is useful for highly reliable products when their failure times are difficult to obtain. Furthermore, we show that the proposed new estimator of the lifetime distribution function is more accurate than the standard and modified maximum likelihood estimators. We also obtain approximate confidence intervals for the lifetime distribution function and its percentiles. Finally, we use light‐emitting diodes as an example to illustrate our method and demonstrate how to validate the Wiener assumption during the testing. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

The building evacuation problem with shared information

In this article, the Building Evacuation Problem with Shared Information (BEPSI) is formulated as a mixed integer linear program, where the objective is to determine the set of routes along which to send evacuees (supply) from multiple locations throughout a building (sources) to the exits (sinks) such that the total time until all evacuees reach the exits is minimized. The formulation explicitly incorporates the constraints of shared information in providing online instructions to evacuees, ensuring that evacuees departing from an intermediate or source location at a mutual point in time receive common instructions. Arc travel time and capacity, as well as supply at the nodes, are permitted to vary with time and capacity is assumed to be recaptured over time. The BEPSI is shown to be NP‐hard. An exact technique based on Benders decomposition is proposed for its solution. Computational results from numerical experiments on a real‐world network representing a four‐story building are given. Results of experiments employing Benders cuts generated in solving a given problem instance as initial cuts in addressing an updated problem instance are also provided. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

基于工作流的GIS服务动态聚合方法、技术体系和参考模型研究

基于GIS服务的特点和动态服务聚合的应用实际,提出了一种基于工作流的GIS服务动态聚合实现方法,该方法通过引入服务群的概念,有效适应了GIS服务的动态变化性;提出了基于工作流的GIS服务聚合技术体系,界定了GIS服务聚合的研究内容和层次关系,为GIS服务动态聚合关键技术的研究提供了总体框架和顶层指导;参考工作流的研究成果,提出了动态服务聚合参考模型DSCRM,为开发聚合服务支撵平台以及在此基础上构造特定的服务聚合应用提供了可参考的计算模型.给出了一个GIS服务聚合应用实例来说明工作的可行性和有效性.     

关于半鞅向量随机积分的两个结果

首先利用半鞅Girsanov定理与闭图像定理证明了:若{Xn}是带滤基的完备概率空间(Ω,F,F,P)中的一列半鞅,其中滤基F=(Ft)t≥0满足通常条件,且{Xn}在关于P的Emery拓扑空间中收敛于X,则当概率测度Q相似文献   

攻角对双三角翼旋涡特性影响的数值模拟

采用数值方法研究了双三角翼上涡流运动随攻角的变化规律.计算取层流假设,研究了攻角在5°～30°,76°/40°后掠双三角翼绕流的流场结构随攻角的变化,并对双三角翼上涡破裂现象对流场结构及气动力性能的影响进行了分析.结果表明,双三角翼上的多涡结构存在强烈的相互影响,较大的攻角会导致涡破裂在翼面上发生,严重影响了双三角翼的气动力性能.     

大规模代谢网络分解的生物信息学研究

随着大规模分子相互作用数据的不断涌现,生物学网络方面的研究正日益得到重视.代谢网络处于生物体的功能执行阶段,其结构组成方式不仅反映了生物体的功能构成,也直接影响代谢工程中的途径分析和研究.作为代谢网络研究的重要环节,实现网络的合理分解不仅对于基因组范围内分子网络的结构和功能研究具有重要意义,也是代谢工程的途径分析和优化得以顺利进行的前提之一.在回顾代谢网络宏观结构和拓扑特征研究成果的基础上,通过对现有分解方法的深入分析,指出缺乏合理且有针对性的模型评估准则是目前网络分解研究中亟待解决的问题之一.今后的研究趋势在于如何整合更多的信息和发展更先进的分析方法,建立更合理的模型,并进一步拓展网络分解的应用范围.