The stress intensity for an edge crack in a semi-infinite orthotropic body

The problem of an edge crack in a semi-infinite plane of linear elastic orthotropic material is studied. The correction factor which relates the stress intensity factor for this problem to that for an isolated crack in an infinite body is evaluated for a range of orthotropic material properties. Calculations are restricted to mode I problems. The method requires the numerical solution of an integral equation, the integrands in which are derived from related complex variable solutions.

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Resumé On étudie le problème d'une fissure de bord dans un plan semi-infini en un matériau linéaire eastique et orthotrope. On évalue pour une gamme de propriétés orthotropes du matériau le facteur de correction qui permet de relier le facteur d'intensité de contraintes relatif à ce problème à celui relatif à une fissure isolée dans un corps infini. Ces calculs sont limités aux problèmes de rupture selon le mode. I. La méthode exige de trouver la solution numérique d'une intégrale dont les intégrants sont tirés de solutions associées à variables complexes.

     

Forces required to jettison a simulated S92 passenger exit: Optimal helicopter underwater egress training techniques

This paper outlines the first known examination of the forces required to jettison a simulated exit used during helicopter underwater egress training (HUET). To capture the forces placed on the simulated cabin exit, a purpose build force plate was designed to replace an existing simulator exit used during HUET. A 25-point map was created to identify specific jettison forces required across the entire exit surface. Ten participants completed a total of 120 underwater egress sequences in–air and in-water from a normal flight and fully compressed crash attenuating seat position. The results indicate that the force required to jettison the simulated exit is significantly different in relationship to location on the exit surface. From the results, it can be concluded that helicopter underwater egress training protocols should ensure that offshore candidates are informed of the different force requirements as well as have the opportunity to practice jettisoning a high physical fidelity exit from a fully compressed crash attenuating seat.     

Modeling the large‐strain constitutive behavior of polycarbonate under isothermal and anisothermal conditions

The tensile behavior of polycarbonate was studied at large strains below the glass‐transition temperature. Experiments were carried out at a series of constant temperatures and also under conditions of falling temperatures. The specimens necked with a natural draw ratio of approximately 2, and the study was mainly focused on the necked material. Isothermal experiments revealed an elastic mechanism that initiated beyond the natural draw ratio. A model consisting of an Eyring process and two Gaussian elastic mechanisms was found to be applicable to both the isothermal and anisothermal stress‐relaxation and stress–strain results. The same model also produced reasonable estimates of the stresses generated during the necking process. In addition, a simple relationship between the isothermal and anisothermal stress relaxation was demonstrated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2105–2116, 2005     

基于重力坝三维设计的CAD动态交互系统开发

为了在可研阶段合理、快速地制定重力坝设计方案,减少设计周期和成本,采用极限状态设计的方法,利用VB 6.0可视化编程工具开发出了一套能够与CAD动态交互的重力坝三维设计系统。该系统通过对Auto-CAD的二次开发实现了重力坝的三维参数化建模,并对所建三维模型进行结构计算,将设计与计算紧密结合,通过动态交互简化了大量复杂数据的计算,达到精确、快速完成断面设计的目的。经实践检验证明,该系统大大提高了断面设计效率,实用性强,对可研阶段的方案比选具有重大意义。     

Alpha olefin sulfonates from a commercial SO3-Air reactor

Alpha olefin sulfonate (AOS) can be made by SO₃-air sulfonation of straight chain alpha olefins followed by saponification of the neutralized product. The sulfonation step forms unsaturated sulfonic acids, sultones and sultone sulfonic acids. Hydrolysis of the various sultones yields a mixture of unsaturated and hydroxy sulfonates. Sulfonation of commercial mixtures of straight chain alpha olefins in a large-scale SO₃ falling film unit has given AOS of 1.5–3.0% oil based on active content and tristimulus color of about 40% saturation (2% solution) which is readily bleachable with 1–3% NaOCl to about 10–15% saturation. Performance of AOS made from C₁₅−C₁₈ alpha olefin is comparable to that of the high-foaming C₁₁−C₁₄ LAS in both detergency and dishwashing foam. It is superior to similar products made from internal straight chain olefins. The product shows a low order of toxicity and biodegrad-ability slightly better than that of LAS. A C₁₅−C₁₆ AOS blend is especially attractive in liquid detergent formulations. Presented at the AOCS Meeting, Los Angeles, April 1966.     

Root growth and phosphorus and potassium uptake by two corn genotypes in the field

In a field study P and K uptake by two corn (Zea mays L.) genotypes which differed in root growth was investigated. The effect of differences in root growth on P and K uptake was assessed using a mechanistic-mathematical model which describes nutrient uptake by growing plant roots in soil. Nitrogen was applied at 0 and 227 kg ha^–1 to Pioneer 3732 and B73xMo17 corn grown on Raub silt loam (fine-silty, mixed, mesic Aquic Argiudoll) and at 227 kg N ha^–1 to these two genotypes on Chalmers silt loam (finesilty, mixed, mesic, Typic Haplaquoll). Root growth and P and K uptake by the two corn genotypes was measured 31, 47, 75 and 91 d after planting on the Raub and 31, 47, 61 and 75 d after planting on the Chalmers soil.Root growth and P and K uptake by B73xMo17 was greater than that of Pioneer 3732 on N-fertilized Raub soil. On Chalmers soil the difference in root growth between the two genotypes resulted in an increase in K but not P uptake. The higher soil P level of the Chalmers appears to have offset possible differences in P uptake due to root size. There were no differences between the two genotypes in either the percentage of roots with root hairs, or the density or length of root hairs. Phosphorus and K uptake calculated with the simulation models for both corn genotypes on both soils over each of three growth periods agreed with observed P (Y = 0.68X + 1.71; r = 0.944^**) and K (Y = 0.88X + 15.52; r = 0.928^**) uptake. Differences in P and K uptake between B73xMo17 and Pioneer 3732 resulted primarily from the difference in root growth in the topsoil. A high correlation was found between root surface area and P (r = 0.893^**) and K (r = 0.928^**) uptake by both corn genotypes on both the soils.Journal paper No. 10,316 Purdue Univ. Agric. Exp. Stn., W. Lafayette, In 47906. Contribution from the Dep. of Agron. This paper was supported in part by a grant from the Tennessee Valley Authority.     

晶界对低压电解电容器铝箔腐蚀结构的影响

采用扫描电子显微镜和背散射电子取向成像技术分析研究了低压电解电容器用阳极铝箔的腐蚀结构、晶粒尺寸和晶界分布对比电容的影响及相关机理.结果表明,在铝箔的晶界附近,尤其是大角度晶界附近容易出现尺寸较大的腐蚀孔坑或沟道,造成腐蚀结构的不均匀性并降低比电容.该晶界优先腐蚀的现象起因于晶界的高缺陷密度和与之相应的腐蚀电流密度的局部集中.增加晶界密度可以降低杂质原子偏聚程度和电流密度分布的不均匀性,因此在一些特定的电化学腐蚀条件下可以借助减小晶粒尺寸的方式提高比电容.     

圆锯片综合特性检测系统的硬件设计

圆锯片综合特性检测系统是根据国内外学者的圆锯片适张研究成果和频谱分析、坐标映射的理论,综合计算机技术、传感器技术、信号调理技术和数据采集处理技术来开发的,检测系统软件是Visual C 开发,在Win32环境下运行.整个检测系统操作简便、人机界面友好、具有较强数据管理功能,能在工业现场条件下快速、准确、无损地检测圆锯片适张状态.     

The biological properties of Aerococcus antagonists, representatives of human microbiocenoses

The paper deals with the data on biology of Aerococcus, a slightly studied group of microorganisms. Physiological-biochemical properties of Aerococcus are described, data of their distribution in nature are given. Peculiar attention is paid to the estimate of the role of Aerococcus in human microbiocenoses. As a result of the profound and all-round study of this group of microorganisms the authors have developed new bacterial drug "A-bakterin" based on the aerococcus strain. Data presented about the results of clinical tests of "A-bakterin" are presented, a possibility to use Aerococcus lysate in the elaboration of new drugs is discussed.     

Recent advances in amperometric glucose biosensors for in vivo monitoring

The substance-use, positive health practices, diet and eating habits, driving behaviours and preventive health care practices of 113 nurses living in the southeast of England were assessed by means of a postal questionnaire. Females were generally more compliant than males with most of the behaviours assessed. Females reported taking greater risks with driving behaviours by an occasional tendency to "drink and drive". Many males reported both a lack of knowledge of how to self-examine their testicles for signs of cancer and little compliance with this behaviour. This sample reported more smoking and alcohol use than previously reported samples of American nurses and U.K. norms. The nurses in this sample were more likely to avoid foods high in cholesterol, add fibre to their diet and be more vigilant in their driving behaviour than American nurses and British non-nurses.