Lattice type of fracture model for concrete

Concrete is usually described as a three-phase material, where matrix, aggregate and interface zones are distinguished. The beam lattice model has been applied widely by many investigators to simulate fracture processes in concrete. Due to the extremely large computational effort, however, the beam lattice model faces practical difficulties. In our investigation, a new lattice called generalized beam (GB) lattice is developed to reduce computational effort. Numerical experiments conducted on a panel subjected to uniaxial tension show that the GB lattice model can reproduce the load-displacement curves and crack patterns in agreement to what are observed in tests. Moreover, the effects of the particle overlay on the fracture process are discussed in detail. (C) 2007 Elsevier Ltd. All rights reserved.

振荡流中圆柱受力测量研究

本文叙述了测量振荡流中圆柱受力大小和性质的方法和步骤。给出了测量结果,并首次给出这种力的频谱特性。

苏联低温等离子体主要研究单位一览

<正> 低温等离子体由于能提供一般矿物燃料所不能提供的高温、可控气氛、高纯度,且容易实现自动化控制,因此,许多国家都在化工、冶金、机械加工、半导体等工艺过程中开展了大量的等离子体技术应用研究,有的已成为成熟的工艺,苏联西伯利亚储藏着极丰富的矿物燃料资源,但距离工业发达的苏联欧洲部分遥远,据估计,如果苏联欧洲部分的工业全部用

使用任意非正交曲线坐标解变截面圆轴扭转问题的数值计算

<正> 1.基本方程及其数值求解由于讨论的是轴对称问题,因此取柱坐标系中的θ坐标为任意曲线坐标系(q~1,q~2,q~3)中的q~2坐标,在轴纵剖面Z—R平面上取任意非正交曲线坐标q~3和q~1,则变截面圆轴扭转问题以无量纲应力函数ψ表达的求解方程为:

Rubens Paiva

Apresenta ensaio biográfico, discursos, cronologia, fotografias e documentos sobre a trajetória pessoal e política de Rubens Paiva.

Asymptotic solution of mode-iii crack in damaged softening materials

In this paper, a constitutive model of elasticity coupled with damage suggested by Lemaitre et al, [1] is used. The macroscopic stress-strain response of the model includes two stages: strain hardening and strain softening. The basic equation is derived for the anti-plane shear problem. Several lowest order asymptotic solutions are obtained, and assembled for the crack-tip fields.

O lado invisível da participação política : gestão da informação dos mecanismos digitais de participação política nos parlamentos da América Latina, com uma análise do caso da Câmara dos Deputados do Brasil

Examina uma das dimensões dos mecanismos digitais de interação e participação política oferecidos por parlamentos para a sociedade - a gestão da informação. São mapeadas as formas de participação política empregadas nos portais legislativos da América Latina, com o objetivo de conhecer as informações que cercam as iniciativas e contextualizar o estudo de caso da Câmara dos Deputados do Brasil. Procura-se entender como a Câmara dos Deputados do Brasil realiza a coleta, a organização, a distribuição, o armazenamento e o uso da informação concernente aos mecanismos de interação e participação política, de caráter multilateral, empregados em seu Portal. Conclui-se que os parlamentos latino-americanos colocam à disposição da sociedade dezenas de canais digitais de interação e participação, como uma tendência irreversível das democracias modernas, mas a gestão da informação inerente às experiências ainda é um desafio a ser alcançado.

Evaluation of wheat or corn dried distillers' grains with solubles on performance and carcass characteristics of feedlot steers

[EN]A study was conducted on crossbred steers (n=275; 376±924 kg) to evaluate performance and carcass quality of cattle fed wheat or corn dried distillers’ grains with solubles (DDGS). The control ration contained 86.6% rolled barley grain, 5.7% supplement and 7.7% barley silage (DM basis). The four treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. Steers were slaughtered at a common end weight of 645 kg with 100 steers randomly (n=20 per treatment) selected for determination of the retail yield of sub-primal boneless boxed beef (SPBBB). Data were analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS led to a quadratic increase in dry matter intake (DMI) (P<0.01), whereas increasing levels of corn DDGS led to a quadratic decrease in DMI (P=0.01). Average daily gain was not influenced (P=0.13) by feeding wheat or corn DDGS, but cattle fed corn DDGS exhibited a quadratic increase (P=0.01) in gain:feed. As a result, a quadratic increase (P<0.01) in calculated NEg of the diet was observed as corn DDGS levels increased. A linear decrease (P=0.04) in days on feed (169, 166 and 154 d) was noted when increasing levels of wheat DDGS (0, 20 and 40%) were fed. Dressing percentage increased in a linear fashion with wheat DDGS (P<0.01) inclusion level and in a quadratic fashion (P=0.01) as corn DDGS inclusion level increased although other carcass traits were not affected (P=0.10) by treatment. The results indicate that replacement of barley grain with corn or wheat DDGS up to 40% of the diet (DM) can lead to superior performance (improved gain:feed or reduced days on feed, respectively) with no detrimental effect on quality grade or carcass SPBBB yield.

Eutrophication in the Chesapeake Bay

The most critical long-term threat to the continued health of the Chesapeake Bay is the addition of excess nutrients to the estuarine waters. Other problems, such as Kepone and the disappearance of aquatic vegetation (which is possibly linked with nutrient loading), may steal our attention for short periods,but these difficulties will, hopefully, recede in due time. The projected growth of population in the near environs of the Bay, however, indicates that,as a problem, eutrophication will probably continue well into the next century