Web应用日志分析系统分析与设计

互联网的蓬勃发展为生活、学习、工作提供了诸多便利,但随之而来的网络安全隐患日趋明显.应用日志分析作为一种重要的信息安全保障措施,有效地弥补了传统安全防御技术的缺陷.主要分析了传统日志分析的常用方法,并在此基础上,提出了一种新的日志读取方法和模式匹配算法.通过测试表明,这些改进对提高日志的分析效率起到了积极效果.     

用负阻法实现S波段低相噪压控振荡器设计

采用分布式微带电路结构和负阻振荡法设计了频率范围为2．4—2．8GHz的压控振荡器（VCO）,根据ADS软件进行建模并仿真,确定了VCO的电路参数,同时对振荡器的相位噪声和输出功率等关键参数进行了仿真优化。最终通过对实际制作出的VCO测量,验证了该模型的准确性,频段内的相位噪声达到-90dBc,Hz@10KHz,输出功...     

A parallel direct solver for the self-adaptive hp Finite Element Method

In this paper we present a new parallel multi-frontal direct solver, dedicated for the hp Finite Element Method (hp-FEM). The self-adaptive hp-FEM generates in a fully automatic mode, a sequence of hp-meshes delivering exponential convergence of the error with respect to the number of degrees of freedom (d.o.f.) as well as the CPU time, by performing a sequence of hp refinements starting from an arbitrary initial mesh. The solver constructs an initial elimination tree for an arbitrary initial mesh, and expands the elimination tree each time the mesh is refined. This allows us to keep track of the order of elimination for the solver. The solver also minimizes the memory usage, by de-allocating partial LU factorizations computed during the elimination stage of the solver, and recomputes them for the backward substitution stage, by utilizing only about 10% of the computational time necessary for the original computations. The solver has been tested on 3D Direct Current (DC) borehole resistivity measurement simulations problems. We measure the execution time and memory usage of the solver over a large regular mesh with 1.5 million degrees of freedom as well as on the highly non-regular mesh, generated by the self-adaptive hp$hp$-FEM, with finite elements of various sizes and polynomial orders of approximation varying from p=1$p=1$ to p=9$p=9$. From the presented experiments it follows that the parallel solver scales well up to the maximum number of utilized processors. The limit for the solver scalability is the maximum sequential part of the algorithm: the computations of the partial LU factorizations over the longest path, coming from the root of the elimination tree down to the deepest leaf.     

Parameter sensitivity study of the Nelder-Mead Simplex Method

This paper presents a parameter sensitivity study of the Nelder-Mead Simplex Method for unconstrained optimization. Nelder-Mead Simplex Method is very easy to implement in practice, because it does not require gradient computation; however, it is very sensitive to the choice of initial points selected. Fan-Zahara conducted a sensitivity study using a select set of test cases and suggested the best values for the parameters based on the highest percentage rate of successful minimization. Begambre-Laier used a strategy to control the Particle Swarm Optimization parameters based on the Nelder Mead Simplex Method in identifying structural damage. The main purpose of the paper is to extend their parameter sensitivity study to better understand the parameter’s behavior. The comprehensive parameter sensitivity study was conducted on seven test functions: B2, Beale, Booth, Wood, Rastrigin, Rosenbrock and Sphere Functions to search for common patterns and relationships each parameter has in producing the optimum solution. The results show important relations of the Nelder-Mead Simplex parameters: reflection, expansion, contraction, and Simplex size and how they impact the optimum solutions. This study is crucial, because better understanding of the parameters behavior can motivate current and future research using Nelder-Mead Simplex in creating an intelligent algorithm, which can be more effective, efficient, and save computational time.     

FMM能效分析及其ASIC可行性评估

对快速多极方法(FMM)进行研究,分析其关键计算任务,并在CPU与DSP上进行验证,得出FMM在不同平台上性能和功耗的量化分析结果,给出基于FMM的多核DSP可重构ASIC结构模型。以可重构硬件FPGA为例,对该模型进行预测,结果证明其在涉及大规模浮点计算时具有一定的能效优势。     

Method for analysis and dynamism of factory structure in automotive manufacturing

A turbulent environment characterized by unsteady economic cycles, customized products, a growing bandwidth of products, an exploding number of variants and shorter product life cycles force manufacturers to permanent adaptation of their factories. Flexible and changeable structures will be required to enable factories dealing with the technological challenges and economic pressure of the future competitively. In order to achieve changeability objectives in manufacturing, a detailed analysis of existing structures and its representative attributes is essential. It is the basis for systematic structure planning of factories. In this paper a method for analyzing the capacitive and technological structure of a factory embedded in a network of manufacturing and its network of suppliers is presented. The synchronization of product and production development under the influence of change is intended. Therefore, the structural views of product and production are specifically in focus of the method. Based on the results of the analysis models an approach of a tool for giving product and production structure dynamism is suggested to investigate the effects and dependencies of change drivers in manufacturing.     

Approximate periodic solutions for the Helmholtz-Duffing equation

Approximate periodic solutions for the Helmholtz-Duffing oscillator are obtained in this paper. He’s Energy Balance Method (HEBM) and He’s Frequency Amplitude Formulation (HFAF) are adopted as the solution methods. Oscillation natural frequencies are analytically analyzed. Error analysis is carried out and accuracy of the solution methods is evaluated.     

First-principles calculation of L10 -disorder phase equilibria for Fe–Ni system

By combining Cluster Variation Method with FLAPW electronic structure total energy calculations and the Debye–Grüneisen theory within quasi-harmonic approximation, L1₀-disorder phase equilibria for Fe–Ni system are calculated. The transition temperature, 483 K, determined in the present calculation is lower than that obtained in the previous calculation without thermal vibration effects. The decrease of the transition temperature is ascribed to the enhanced phase stability of a disordered phase due to the thermal softening of a lattice.     

汉语概念复合块的自动分析

为解决句法分析任务中的块边界识别和块内结构分析问题,该文基于概念复合块描述体系进行了块分析探索。通过概念复合块与以往的基本块和功能块描述体系的对比分析,深入挖掘了概念复合块自动分析的主要难点所在,提出了一种基于“移进-归约”模型的汉语概念复合块自动分析方法。在从清华句法树库TCT中自动提取的概念复合块标注库上,多层次、多角度对概念复合块自动分析性能进行了纵向与横向评估,初步实验结果证明了该分析方法对简单概念复合块分析的有效性,为后续进行更复杂的概念复合块的句法语义分析研究打下了很好的基础。     

航天软件设计、分析可靠性研究

在航天型号的研制过程中,软件的可靠性十分重要。而目前有关软件产品的可靠性设计、分析方法仍十分缺乏。该文提出了一种综合采用在硬件可靠性设计分析领域已成功应用的FTA、FMEA及建立软件产品的功能剖面的方法,力图进一步提高软件产品的可靠性。