双因素方差分析方法的比较

双因素方差分析是一种应用非常广泛的统计分析方法。文章讨论了有交互作用的双因素方差分析,然后作为特例说明无交互作用的双因素方差分析,并通过两个例题对两种方法的应用进行比较,使双因素方差分析在理论上更加完善。

方差分析在跳水运动成绩管理中的应用

跳水运动员的成绩普遍采用裁判员打分的形式,所以跳水运动员的成绩除了受运动员动作完成情况影响外,还受到裁判员主观因素的影响。文章采用有交互作用的双因素方差分析方法,对跳水运动员成绩进行评价,分析运动员、裁判员和裁判员对运动员的主观因素对跳水运动员成绩的影响,为客观、公正评价运动员的成绩和裁判员评分水平,提供了理论支持。

部队装备新旧状态的大数据分析

对已获得的模拟大数据进行了清洗和关联的预处理工作。以高程、经度、纬度、装备类型、部队种类5个方面作为影响因素,建立了3种方差分析模型,分别讨论了每种因素对装备新、堪、待、废4种状态的影响情况,以及各种因素联合起来产生的联合效应。通过计算相关系数,将每种因素与装备状态的关联程度进行量化比较。所得结论和提出的建议对部队的装备保障优化具有一定的意义。

FEM for Stability Analysis Against Overturning of Portal Water Injection Sheet Pile

Portal water injection sheet pile (PWISP), as a retaining wall, appeared in seashore engineering in 2000. Although there have been many systematic methods addressing the issue, there are very few focusing on the new structure because of the difficulties in defining the earth pressure between the two piles. A new method is proposed in this paper to obtain the earth pressure between the PWISPs. Stability analysis against overturning follows as a consequence. Using Finite Element Analysis (FEA) software ANSYS, both the nonlinear characteristics of the soil and those of the contact elements are taken into account to obtain the earth pressure distribution on the contact surface. Based on the results of the FEA, Rankin’s theory and the slip plane theory, the formula of the earth pressure on the inner surfaces between the piles is given. Assuming the PWISP as the analysis object and the earth pressure as an outside force acting upon it, the equation of stability against overturning of the PWISP is presented. Finally, some parameters are discussed about the stability of the PWISP against overturning, such as the embedded depth of the front pile, the distance between the two rows of piles, the internal friction angle and the cohesion of the earth. The results show that the increase of the cohesion and the internal friction angle will decrease the distance and the embedded depth, and therefore enhance the stability against overturning. Specifically, when the distance is 1/3-2/3 of the maximal excavation depth, the two rows of piles give the best performance in stability.

Simulation of Blast and Fragment Loading Using a Coupled Multi-Solver Approach

Simulating blast and fragment loading simultaneously in a single computation requires the combined use of multiple states of the art solvers. A pipe bomb is an example of simple improvised explosive device （IED） that consists of a piece of pipe filled with explosive material and capped at both ends. To simulate the explosion of a pipe bomb and the damage it causes, a coupled multisolver approach based upon finite element and finite volume methods is applied. The numerical calculation presented demonstrates the ability of ANSYS AUTODYN to correctly simulate the threats of IEDs and provides insight into how the most significant physical phenomena affect the results.

Splitting PMMA with Mini Cutting Explosives

In order to improve the present aviation ejection escape system, the application of explosion cutting technique to aviation escape system is proposed to weaken the strength of canopy before ejecting it. A series of mini cutting explosives are designed to investigate the process of splitting PMMA plate. The phenomenon of spallation in PMMA is observed. The effects of different parameters of mini cutting explosives on the cutting depth are obtained. Consequently the appropriate material of half-circular metal covers, explosive types and the ranges of charge quantities are determined. On the other hand, the cutting process of aviation PMMA plate by mini cutting explosives is simulated by means of nonlinear dynamic analysis code LS-DYNA. In finite element analysis,Arbitrary Lagrangian Euler (ALE) algorithm is used to depict the fluid property of high energy explosives. Continuous damage material model is used to simulate the complicate dynamic damage behavior of PMMA due to explosion shock waves. Only sliding contact option is defined to fulfill the fluid-structure interaction between explosives and PMMA plate by distributed parameter methods. Phenomenon of spallation observed in the experiment is presented in the simulation. The relationship between the penetration depth of PMMA plate and charge linear density obtained by numerical simulation agrees well with experimental result.

Comparative Analysis of Seismic Response Characteristics of Pile-Soil-Stnicture Interaction System

The study on the earthquake-resistant performance of a pile-soil-structure interaction system is a relatively complicated and primarily important issue in civil engineering practice. In this paper, a computational model and computation procedures for pile-supported structures, which can duly consider the pile-soil interaction effect, arc established by the finite clement method. Numerical implementation is made in the time domain. A simplified approximation for the seismic response analysis of pile-soil-structure systems is briefly presented. Then a comparative study is performed for an engineering example with numerical results computed respectively by the finite clement method and the simplified method. Through comparative analysis, it is shown that the results obtained by the simplified method well agree with those achieved by the finite element method. The numerical results and findings will offer instructive guidelines for earthquake-resistant analysis and design of pile-supported structures.

Direct Urca Processes with Hyperon-Hyperon Interactions

With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic mean field theory （RMFT） including σ＊ and φ mesons, in comparison with the results calculated with the strong YY interaction and with no （σ＊ ,φ ） mesons included. In neutron star matter, the weak YY interaction supplies the additional repulsive interaction between hyperons while the strong YY interaction supplies the attractive one. With the weak YY interaction, the effective masses of hyperons are larger than those with the strong YY interaction while smaller than those with no （σ＊ ,φ） mesons included. The threshold star masses for the DURCA processes involving nucleons and A are not sensitive to the strength of the YY interaction. The weak YY interaction leads to larger threshold masses for the DURCA process involving [1]1 and [1]0 than the other two cases. The process involving [1]0 can take place in the neutron star only when the weak YY interaction is used. The weak YY interaction is able to bring in the agreement with the observation of the neutron star with larger mass and faster cooling than the strong YY interaction.

An Extraction of the Dominant Rotor-Stator Interaction Modes by the Use of Proper Orthogonal Decomposition (POD)

The Proper Orthogonal Decomposition method is applied to the instantaneous velocity field within the rotor-stator inter-row region of a high-speed high-pressure centrifugal compressor. The processed data come from experiments and numerical simulations. In comparison with a Fourier transform, the POD gives the best modal approximation for both initial fields, in terms of the energy expressed on any given number of modes to be taken into account： to reach 98% of the total energy of the velocity field, the required number of POD modes is around nine times smaller than the number of Fourier harmonics. The individual POD modes are given and show that the unsteady rotor-stator interaction is already present in the very first modes.