Reliability-based design optimization applied to structures submitted to random fatigue loads

Structural and Multidisciplinary Optimization - The reliability-based design optimization (RBDO) aims to find the most balanced design through a compromise between cost and safety when...     

Multiple responses analysis and modeling of Fenton process for treatment of high strength landfill leachate

Landfill leachate is one of the most recalcitrant wastes for biotreatment and can be considered a potential source of contamination to surface and groundwater ecosystems. In the present study, Fenton oxidation was employed for degradation of stabilized landfill leachate. Response surface methodology was applied to analyze, model and optimize the process parameters, i.e. pH and reaction time as well as the initial concentrations of hydrogen peroxide and ferrous ion. Analysis of variance showed that good coefficients of determination were obtained (R2 > 0.99), thus ensuring satisfactory agreement of the second-order regression model with the experimental data. The results indicated that, pH and its quadratic effects were the main factors influencing Fenton oxidation. Furthermore, antagonistic effects between pH and other variables were observed. The optimum H2O2 concentration, Fe(II) concentration, pH and reaction time were 0.033 mol/L, 0.011 mol/L, 3 and 145 min, respectively, with 58.3% COD, 79.0% color and 82.1% iron removals.     

Processing Properties of Beef Semimembranosus Muscle as Affected by Electrical Stimulation and Postmortem Treatment

Semimembranosus muscles from paired sides-electrically stimulated (ES) and not-stimulated (NES)-of mature cows were used to determine effects of certain postmortem treatments (state of rigor/temperature) and of ES on processing properties. ES decreased (P<0.05) pH values for prerigor, prerigor/frozen and postrigor/frozen muscles, but did not affect (P>0.05) values for total protein or juice loss during cooking. State of rigor/temperature treatment affected pH and salt-soluble protein (SSP) values more than did ES treatment. pH values differed (P<0.05) between each state of rigor/temperature treatment for both ES and NES samples. Salt-soluble protein values were higher (P<0.05) for NES prerigor than for NES postrigor/frozen samples and higher (P<0.05) for NES postrigor than for NES postrigor/frozen samples. SSP values for ES muscles were higher (P<0.05) for ES postrigor samples than for ES postrigor/frozen samples but were not different for other comparisons. Regardless of ES treatment, freezing of semimembranosus muscles increased pH values (P<0.05) and decreased SSP values (P<0.05) in three of four comparisons.     

Energy Consumption in Tungsten Extractive Metallurgy

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A fuzzy approach for the earned value management

The Earned Value technique is a crucial technique in analyzing and controlling the performance of a project which allows a more accurate measurement of both the performance and the progress of a project. This paper presents a new fuzzy-based earned value model with the advantage of developing and analyzing the earned value indices, and the time and the cost estimates at completion under uncertainty. As the uncertainty is inherent in real-life activities, the developed model is very useful in evaluating the progress of a project where uncertainty arises. A small example illustrates how the new model can be implemented in reality.     

冷轧堆前处理加工在民丰厂的实践

介绍了冷轧堆前处理加工大生产的经验,包括设备组成;助剂及工艺条件优选;技术关键及有待改进的方面等等。     

二维线性弹性问题的等几何边界元分析

引入基于推广B样条的等几何分析方法对二维弹性问题进行边界元分析.首先使用推广B样条表示待分析的问题域,可以精确地表示待求域的圆弧边界;然后使用边界积分方程对边界未知量求解,将求得的位移通过细分方法插值到边界上;最后通过重心坐标法求得域内解,减少计算复杂度,提高了计算的精确度.分片测试及其他实例结果证实了该方法的有效性.