On crushing response of the three-dimensional closed-cell foam based on Voronoi model

The crushing response of the three dimensional closed-cell foams is investigated using mesoscale numerical models based on Voronoi tessellation. The crushing stress at the impact and stationary sides of the Voronoi structures are obtained. The effects of the impact velocity, the cell shape irregularity degree, the relative density, inertia of cell walls and the dependence of the base material on the crushing stress are discussed. Meanwhile, the contention of the rate dependency of cellular materials are expounded by the comparison of numerical results of the Voronoi model and solid continuum model as well as the shock wave theory, in which the densification strain and plateau stress are calculated using the energy absorption efficiency approach.     

Voronoi多边形在网点规划决策支持系统的应用

分析当前网点影响区域的几种常见划分方法。论述一种逐步加点并修改的构造Voronoi多边形的算法,可以同时算出相应修改点之间的拓扑关系,提出了对Voronoi多边形划分方案进一步修正的方法,并详述了构造Voronoi多边形在开发网点规划决策支持系统中网点影响区域划分的应用。     

基于Voronoi图理论的最优刀具轨迹规划算法的研究

基于面向对象的Ｖｏｒｏｎｏｉ图理论,研究了整齐等距线与Ｖｏｒｏｎｏｉ多边形的交点存在性问题及在有瓶颈的情况下交点个数的判别定,并根据交点状点变换规则,应用三种堆栈,以线性的时间复杂实现了整齐等距线的生成和型腔加工的最优刀具轨迹规划算法。该算法已成功地应用于ＮＣ加工中。     

设计模式在MIS中的应用

以网络资源管理系统为例,详细讨论了抽象工厂、观察者、模板方法、模型-视图-控制器模式,以及在MIS系统中如何有效使用设计模式来提高程序的扩展性和维护性.     

Multiple cohesive crack growth in brittle materials by the extended Voronoi cell finite element model

This paper is aimed at modeling the propagation of multiple cohesive cracks by the extended Voronoi cell finite element model or X-VCFEM. In addition to polynomial terms, the stress functions in X-VCFEM include branch functions in conjunction with level set methods and multi-resolution wavelet functions in the vicinity of crack tips. The wavelet basis functions are adaptively enriched to accurately capture crack-tip stress concentrations. Cracks are modeled by an extrinsic cohesive zone model in this paper. The incremental crack propagation direction and length are adaptively determined by a cohesive fracture energy based criterion. Numerical examples are solved and compared with existing solutions in the literature to validate the effectiveness of X-VCFEM. The effect of cohesive zone parameters on crack propagation is studied. Additionally, the effects of morphological distributions such as length, orientation and dispersion on crack propagation are studied.     

Modeling of interfacial debonding crack in particle reinforced composites using Voronoi cell finite element method

In this paper, Voronoi cell finite element method (VCFEM), introduced by Ghosh and coworkers (1993), is applied to describe the matrix-inclusion interfacial debonding for particulate reinforced composites. In proposed VCFEM, the damage initiation is simulated by partly debonding of the interface under the assumption of the critical normal stress law, and gradual matrix-inclusion separations are simulated with an interface remeshing method that a critical interfacial node at the crack tip is replaced by a node pairs along the debonded matrix-inclusion interface and a more pair of nodes are needed to be added on the crack interface near the crack tip in order to better facilitate the free-traction boundary condition and the jumps of solution. The comparison of the results of proposed VCFEM and commercial finite element packages MARC and ABAQUS. Examples have been given for a single inclusion of gradually interfacial debonding and for a complex structure with 20 inclusions to describe the interfacial damage under plane stress conditions. Good agreements are obtained between the VCFEM and the general finite element method. It appears that this method is a more efficient way to deal with the interfacial damage of composite materials. The financial support by the Special Funds for the National Major Fundamental Research Projects G19990650 and the National Natural Science Foundation of China No. 59871022 are gratefully acknowledged.     

Quantitative analysis of the microstructural homogeneity of zirconia-toughened alumina composites

The Voronoi diagram approach was applied to quantify the level of microstructural homogeneity of ceramic ZTA samples. From SEM pictures of polished cross-sections of ZTA samples a point pattern representing the distribution of the zirconia phase in the composite was generated. This point pattern was converted into a Voronoi diagram. The level of microstructural homogeneity was quantified by statistical analysis of the relevant properties (area, perimeter and number of faces) of the Voronoi polygons. A dimensionless parameter defining the level of microstructural homogeneity was calculated from the different sets of statistical data. The calculated parameters indicated significant differences in homogeneity between the ZTA samples. These differences were in qualitative agreement with previously published wear rates of the same ZTA composites. This illustrates the relevance of microstructural homogeneity for wear performance.     

The design of a DFSA based pattern matcher

Abstract

In order to eliminate the irrelevant data being transferred from disks into memory, many database machines adopt a data filter to filter out the irrelevant data on‐the‐fly. This paper proposes a new DFSA (Deterministic Finite State Automata) based pattern matcher to be implemented as the data filter. It can perform various searching operations, including fixed and variable length don't care patterns. The architecture of this pattern matcher is relatively simple and can be easily implemented by off‐the‐shelf LSI chips. In our design, it only requires one 16K×8 SRAM and five LSI chips for a given state transition table of 128 states.

A test has been conducted to compare the performance of dBASE III and our data filter. The result shows that the data filter is, on average, five times better than the performance of dBASE III.     

Simulating the pervasive fracture of materials and structures using randomly close packed Voronoi tessellations

Under extreme loading conditions most often the extent of material and structural fracture is pervasive in the sense that a multitude of cracks are nucleating, propagating in arbitrary directions, coalescing, and branching. Pervasive fracture is a highly nonlinear process involving complex material constitutive behavior, material softening, localization, surface generation, and ubiquitous contact. A pure Lagrangian computational method based on randomly close packed Voronoi tessellations is proposed as a rational and robust approach for simulating the pervasive fracture of materials and structures. Each Voronoi cell is formulated as a finite element using the Reproducing Kernel Method. Fracture surfaces are allowed to nucleate only at the intercell faces, and cohesive tractions are dynamically inserted. The randomly seeded Voronoi cells provide a regularized random network for representing fracture surfaces. Example problems are used to demonstrate the proposed numerical method. The primary numerical challenge for this class of problems is the demonstration of model objectivity and, in particular, the identification and demonstration of a measure of convergence for engineering quantities of interest. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.     

Computer simulations for the design of microstructural developments in ceramics

This paper is to study the computer simulation of microstructural developments in ceramics mainly by Monte Carlo (MC) model and partly by molecular dynamics (MD). Plural mechanisms of mass transfer were introduced in the MC simulation of sintering and grain growth in ceramics at micron-size particle. The MC simulations were performed at the array of two-dimensional triangular lattices and were developed to sintering and grain growth in the complex systems involving a liquid phase and the second solid phase. The MD simulation was applied to the sintering of nano-size particles of ionic ceramics and showed the characteristic features in sintering process at atomic levels. The MC and MD simulations for sintering process are useful for microstructural design for ceramics.     

一种新型的OFDM智能天线

根据自适应天线阵列理论，结合给定的参考波束的误差，引入虚拟干扰的概念，对目标波束图形状进行调整，提出一种新的可以应用于任意类型天线阵列的波束综舍算法．应用提出的新算法，在主辩和旁瓣位置都可以对波束进行有效的调节．最终获得阵列的最优权矢量，能够最小化目标波束图与参考波束图间的差异．理论分析与仿真结果表明，与现有的同类算法相比，该算法能更有效地获得与参考波束基本相符的波束．应用于OFDM智能天线系统时，对不同子载波频率上信号进行单独处理，利用该算法进行波束综合，能够在整个有效频段，使所有子载波上获得基本一致的阵列输出．     

灰色接近关联度在香料指纹图谱模式识别中的应用

灰色关联分析是灰色系统理论中十分活跃的一个分支,其基本思想是根据序列曲线的几何形状的相似程度来判断其联系是否紧密。曲线越接近,相应序列之间的关联度就越大,反之就越小。文章系统地介绍灰色接近关联度基本理论和两种面积的算法,详细地说明灰色接近关联度的计算方法及使用范围以及在色谱指纹图谱中的应用,包括仪器使用方法及具体计算过程。     

羌族服饰中的羊角纹图案构成与设计思想研究

目的 研究川西北岷江流域羌族服饰中的羊角纹图案构成法则与设计思想。使人们更深入地理解羌族羊角纹图案元素的起源、寓意及构成,提升民众对其设计思想的发掘与认知,使羌族服饰图案文化得到更好的创新、发展与传承。方法 通过文献研究、田野调查收集羌族羊角纹图案,并对其进行单独纹样归类整理和构成形式分析,然后通过结构原理分析与寓意提取,归纳设计思想。结论 通过研究川西北岷江流域羌族服饰图案中的羊角纹,从单独纹样三大分支(直角羊角纹与回形纹的碰撞、圆角羊角纹与如意纹的融合、正负空间中的几何羊角纹),到组合构成,总结出了适形填充、重复组合、图底反转三种构成法则,以及羊角纹图案设计思想,即几何风格、灵活再生、阴阳相济。     

Coloration using higher order optical interference in the wing pattern of the Madagascan sunset moth

Colour patterns of animals' bodies are usually produced by the spatial distribution of pigments with different colours. However, some animals use the spatial variation of colour-producing microstructures. We have studied one distinctive example of such structurally produced colour patterns, the wing of the Madagascan sunset moth, to clarify the physical rules that underlie the colour variation. It is known that the iridescent wing scale of the sunset moth has the alternate air-cuticle multilayer structure that causes optical interference. The microscopic and optical investigations of various parts of the wing have confirmed that the thickness of the cuticle layers within the scale largely varies to produce the colour pattern. However, it varies in very different ways between the dorsal and ventral sides of the hind wing; the thickness gradually varies on the dorsal side from scale to scale, while the abrupt changes are found on the ventral side to form distinctive borders between differently coloured areas. It is also revealed that an unusual coloration mechanism is involved in the green part of the ventral hind wing: the colour is caused by higher order optical interference of the highly non-ideal multilayer structure. The physical mechanism of the colour pattern formation is briefly discussed with the several mathematical models proposed so far.     

星形立体传声器阵列设计与应用

研究了星形立体传声器阵列。利用粒子群优化算法对每条直线上的阵元进行优化排布,获得了具有较好指向性和较低旁瓣级的阵列阵型。基于优化得到的阵列阵型进行了星形立体传声器阵列的机械结构设计,设计的阵列主体能实现自如地折叠,便于包装和运输。研制了基于这种阵列阵型的声成像定位系统,通过数据仿真分析体现出优化设计阵型的优越性,同时通过实验验证了研制的声成像系统在声源定位中的有效性。     

Recognition of the meaningful dotted pattern from a dotted image

Abstract

Based upon the selective attention in human visual perception, a conceptual computation model performing the recognition of the meaningful dotted pattern from a dotted image will be presented. This consists of two major processes. A passive process performs images partition for the segmentation, and an active process performs distance computation for the pattern recognition. The principle of this model is illustrated by a set of Arabic numerals, and its further application is also pointed out.     

化学模式识别在原产地域产品保护中的应用

介绍了常用的化学模式识别方法,并且对化学模式识别在原产地域产品保护中的应用进行了综述.最后展望了原产地域产品表征和化学模式识别模型优化的发展趋势.     

2D and 3D Multiphysics Voronoi Cells,Based on Radial Basis Functions,for Direct Mesoscale Numerical Simulation (DMNS) of the Switching Phenomena in Ferroelectric Polycrystalline Materials

In this paper, 2D and 3D Multiphysics Voronoi Cells (MVCs) are developed, for the Direct Mesoscale Numerical Simulation (DMNS) of the switching phenomena in ferroelectric polycrystalline materials. These arbitrarily shaped MVCs (arbitrary polygons in 2D, and arbitrary polyhedrons in 3D with each face being an arbitrary polygon) are developed, based on assuming radial basis functions to represent the internal primal variables (mechanical displacements and electric potential), and assuming linear functions to represent the primal variables on the element boundaries. For the 3D case, the linear functions used to represent the primal variables on each of the polygonal surfaces of the polyhedral VCs are the Barycentric Washspress functions. The present 2D MVC is denoted as MVC-RBF, while the 3D MVC is denoted as MVC-RBF-W. Each MVC can represent a single grain or crystallite, with an irregular polygonal shape for the 2D case, and an irregular polyhedral shape for the 3D case. In this work, a nonlinear constitutive model is used to describe the evolution of volume fractions of the constitutive-variants in each grain, as the electric or mechanical loading changes. This constitutive model is based on satisfying a local dissipation inequality in each grain in the polycrystalline that yields the minimum Gibbs free energy in this grain. This requirement should always hold in order to be consistent with the second law of thermodynamics and is used to govern the switching process in each grain in each simulation step. Since the interaction between the grains during the loading cycles has a profound influence on the switching phenomena, it is important to simulate the grains with geometrical shapes that are similar to the real shapes of the grains as seen in the lab experiments. Hence the use of 3D MVCs, which allow for the presence of all the six variants of the constitutive relations, together with the randomly generated crystallographic axes in each grain (or MVC), as done in the present paper, is considered to be the most realistic analytical model that can be used for the direct mesoscale numerical simulation of polycrystalline ferroelectric materials.     

用于湿度独立控制的送风气流组织研究

利用计算流体力学（CFD）对5种不同的气流组织形式进行模拟分析，对每种气流组织下形成的空气含湿量分布进行研究。指出个性化送风和地板送风方式对于去除室内余湿较为有效，有可能作为适于湿度独立控制的送风气流组织形式。     

秦绣抽象几何纹样提取与设计应用

目的 陕西秦绣具有独特的艺术形式和深厚的地域文化特色,具有极高的实用价值和艺术价值。主要研究当代秦绣图案中抽象几何纹样的提取及衍生图案设计方法,并对其进行设计应用,验证相应的设计方法和思路。方法 首先采用分析比较法、归纳总结法、聚类分析法、型谱分析法对秦绣图案的表现题材、色彩、几何纹样、构成形式进行研究。其次,用因子分析法提取典型秦绣样本图案中的色彩、几何纹样设计元素。最后,利用形状文法对几何纹样进行推演及衍生图案设计。结论 将秦绣文化融入到现代设计中,一方面有利于为现代设计注入新的设计文化语言;另一方面有利于秦绣文化的保护与传承,使秦绣文化在数字化时代能实现自我创新。