Stress Concentration Factors for a Circular Hole in Curved Beams Under Bending Loads

Abstract: As a contribution to the field of stress concentration studies, the case of circular hole in curved bar elements under bending is hereby studied. Trend values of stress concentration factors (SCF) are presented based on selected variables of the problem for two critical hole locations. The results will help to identify an SCF law for practical use by applying the statistical method of regression analysis. Two approximations obtained by means of computational methods are compared with those obtained by photoelastic experimental method.     

The rate of corrosion of concrete reinforcement and possibilities of its mathematical modelling

The paper describes a method for the mathematical modelling of steel reinforcement corrosion rate. This method is based exclusively on experimental results and expression of the influence of significant corrosion factors in the form of functional relations. The method takes into account the reality of the effects of corrosion factors, their contigency and complexity, and various circumstances occurring in practice. It represents one way towards the development of methods for the prediction of service life of reinforced concrete and structures.     

A3钢的工业大气腐蚀

在辽宁省工业城市进行 A3钢大气暴露试验。两年后测出不同地点腐蚀率。依据所记录的各试验点的气象数据和污染数据,讨论了 A3钢的大气腐蚀规律。     

VARIATIONS IN ALFALFA JUICE SOLUTE CONCENTRATIONS AS WATER IS EVAPORATED

Alfalfa juice was extracted from plants during the graving phases of the first and second crops. The alfalfa juice was dried and solute concentrations were measured periodically during the process using freezing point depression (FPD) as an indicator. Solute/solvent weight ratios were calculated from the freezing point depression of fresh unconcentrated 'uice extracted from both firsc and second crops. At the time of harvest, tie FPD was a function of this ratio. The first and second crops behaved distinctively different during the drying process, with the second having a larger soluce concentration and a greater FPD at a given moisture content. The appearance of preci itate during the drying process and the general1 large FPD makes this materiay a questionable product for drying vitg low temperature processes.     

A New Method for Comparing Orthonasal and Retronasal Olfaction.

Odors seem to be perceived differently when presented ortho- or retronasally. In this study, stimuli of controlled concentration and duration were applied in either the anterior nasal cavity or epipharynx by means of air-dilution olfactometry. Stimulus concentration was monitored in the olfactory cleft. In Experiment 1, odor thresholds to a food (chocolate) and a nonfood (lavender) odor were lower for orthonasal, compared with retronasal, stimulation. In Experiment 2, intensity ratings to suprathreshold odor concentrations were significantly higher for orthonasal than for retronasal stimulation with hydro- hydrogen sulfide, but not phenyl ethyl alcohol. Accordingly, amplitudes and latencies of olfactory event-related gen potentials to retronasal stimuli were found to be smaller and prolonged, respectively. This indicates differential processing of olfactory stimuli presented through the retronasal or orthonasal routes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

乙烯裂解炉内传递和反应过程综合数值模拟Ⅱ.反应管内传递和反应过程的数值模拟

采用乙烯裂解炉传递反应过程综合数学模型中的反应管数学模型，对工业裂解炉反应管进行了系统的数值模拟，得到了反应管内流场、温度场和浓度场的详细信息，揭示了反应管内流动、传热、传质和裂解反应的基本特点。模拟结果表明，沿反应管轴向油气吸热升温，裂解反应加剧，产物产率逐渐发生变化；沿反应管径向存在明显的流体流速和温度的变化，而产物产率的变化不如流体流速和温度的变化明显。通过比较湍流粘度和分子粘度的大小，认为29．975～30mm的径向区域为层流层，层流层的存在使得临近管壁的区域内流体流速和温度变化显著。     

高砂比压裂技术研究

应用由美国ＮＳＩ公司引进的“ｓｔｉｍｐｌａｎ”拟三维压裂设计软件，对影响裂缝内支撑剂铺置浓度的诸因素进行了灰色关联度分析，从中找出了主要的影响因素。并以高砂比压裂的技术指标为依据，研究了在目前压裂工艺水平下，进行高砂比压裂所必须遵循的原则。文中还对国内的高砂比压裂进行了实例分析，进一步论证了文中的观点。     

T型薄壁管节点应力集中系数有限元分析

通过有限元的方法,分析了T型薄壁管节点受平面内弯矩作用下的疲劳行为,得到了应力最大值的位置和拟合出用于预测T型薄壁管节点受平面内弯矩作用下的应力集中系数的参数公式。     

Stress concentration and fatigue of profiled reinforcing steels

Stress concentrations arise from profiles of ribbed reinforcing steel bars and in this study the results of calculated stress concentration factors (SCF), by using finite element method, are related to the fatigue test results. It is apparent that the degree of confinement of a ribbed bar embedded in concrete not only affects the magnitude of the ultimate bond stress but also the bond stress-slip relation. Thus the rib geometry or profile pattern is designed for optimum bond characteristics and not for fatigue considerations. However the rib geometry influences the fatigue performance through the SCFs arising from the root radius, width and flank angles of the profiles. It is shown that these latter factors have a significant influence on the fatigue behaviour of reinforcing steel bars.     

基于类间分散度和类内集中度的文本特征选择。

特征选择是文本分类的关键步骤之一,所选特征子集的优劣直接影响文本分类的结果。论文首先定义了两种特征分类能力：一种是特征对类间文档的分散程度,该分散度越大越好;另一种是特征对类内文档的聚集程度,该集中度越大越好。然后把这两种特征影响度有机地结合起来设计了一个新的特征选择方法,该方法能够对所选特征进行综合考虑,从而使获得的特征集具有较好的代表性。仿真实验表明所提特征选择方法在一定程度上能够提高文本分类性能。