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991.
A computational methodology for the simulation of the transient aeroelastic response of an unrestrained and flexible aircraft
during high-G maneuvers is presented. The key components of this methodology are: (a) a three-field formulation for coupled
fluid/structure interaction problems; (b) a second-order time-accurate and geometrically conservative flow solver for CFD
computations on unstructured dynamic meshes; (c) a corotational finite element method for the solution of geometrically nonlinear
and unrestrained structural dynamics problems; (d) a robust method for updating an unrestrained and unstructured moving fluid
mesh; and (e) a second-order time-accurate staggered algorithm for time-integrating the coupled fluid/structure semi-discrete
equations of motion. This computational methodology is illustrated with the simulation on a parallel processor of several
three-dimensional high-G pullup maneuvers of the Langley Fighter in the transonic regime, using a detailed finite element
aeroelastic model. 相似文献
992.
{In a seminal paper of 1989, Fredman and Saks proved lower bounds for some important data-structure problems in the cell
probe model. In particular, lower bounds were established on worst-case and amortized operation cost for the union-find problem and the prefix sum problem. The goal of this paper is to turn their proof technique into a general tool that can be applied to different problems
and computational models. To this end we define two quantities: Output Variability depends only on the model of computation. It indicates how much variation can be found in the results of a program with
certain resource bounds. This measures in some sense the power of a model. Problem Variability characterizes in a similar sense the difficulty of the problem.
}
Our Main Theorem shows that by comparing a model's output variability to a problem's problem variability, lower bounds on
the complexity of solving the problem on the given model may be inferred. The theorem thus shows how to separate the analysis
of the model of computation from that of the problem when proving lower bounds.
We show how the results of Fredman and Saks fit our framework by computing the output variability of the cell probe model
and the problem variability for problems considered in their paper. This allows us to reprove their lower bound results, and
slightly extend them. The main purpose of this paper though is to present the generalized technique.
Received January 25, 1999; revised July 30, 1999. 相似文献
993.
994.
本文从互连网发展的趋势入手,对路径模式发掘进行了研究。先简要介绍数据库发掘的概况及网上数据发掘的特点,后结合关联法和组合概率法,并以算法和实例详细对之进行分析。 相似文献
995.
计算机专用实时母系统在VAX/VMS环境下的实现 总被引:3,自引:1,他引:2
“母系统—子系统”的工作方式是计算机专用实时系统研制中的一次重要尝试,本文闸明计算机专用实时母系统在VAX/VMS环境下的工程实现。 相似文献
996.
997.
In this paper, we report some comparative simulations between lattice BGK and lattice Bolzmann schemes for two-dimensional fluid flows. A quantitative assessment of the validity of the lattice BGK and lattice Bolzmann schemes is presented for the two-dimensional weakly compressibleKolmogorov flow. We use this flow to study the difference of the two schemes at small scales. A lowReynolds (R
e 300) number simulation shows the almost identical energy spectra for both schemes except for the small-scale dynamics of lattice Bolzmann which is more noisy. Because of the intrinsic difficulties of nonlinear stability analysis, we use numerical simulations to investigate which scheme is more stable. It turns out the lattice BGK is more stable. It turns out the lattice BGK is more robust than lattice Bolzmann by increasing theReynolds numbers. Detailed comparison with other methods (e.g., spectral method) remains to be done in the near future. 相似文献
998.
通过数值计算的方法分析了色散、自相位调制和激光器啁啾等因素对10Gb/s100kmG.652光纤通信系统的综合效应。对10Gb/sG.652光纤系统中用色散补偿光纤(Dispersion Compensation Fiber,即DSF)的两种方案进行了比较,然后简单讨论了色散补偿光纤在密集波分复用(DWDM)中的应用,最后给出通过以上分析得出的结论。 相似文献
999.
D. C. Voukalis 《International journal of parallel programming》1984,13(4):309-326
Different philosophies lie behind the detecting and correcting error patterns in a real communication channel. The sceptic points in choosing an efficient code, specifically the matrix type-B code, were pointed out in Refs. 1 and 2.Some more points are shown here. As a result the matrix type-B code is found to be a best choice. Some more theoretical aspects for this code are also given. These are useful for the realization and testing of an encoding-decoding algorithm with IC's used in a unique way for its implementation. 相似文献
1000.