钛合金等温锻造进展

等温锻造是一种先进的加工工艺。本文从钛合金高温变形特性、等温锻造参数选择、模具设计、润滑剂摩擦特性等诸方面全面地介绍了这种先进的锻造工艺，它的应用前景及发展方向。     

Post-yield response of cold-cambered wide flange steel beams

The post-yield response of steel beams is important in steel fabrication particularly for setting cambers. A commonly used cambering process known as “cold cambering” consists of bending the girder about its strong axis using single or dual symmetrically applied concentrated loads. This paper recasts available solutions for wide flange steel beams relating loads to permanent deformation in parametric form to determine the effect of cross-sectional geometry and load position on its post-yield response. Sensitivity analyses were then conducted to identify appropriate values of these key parameters and their impact on alternative cambering set-ups. This allows optimization of the cold cambering operation for single- and dual-load systems. The analysis shows that dual-load systems offer significant benefits over single-load systems as they develop the required camber profile at smaller loads without overstraining the steel section. The best results are obtained if the spacing between the two loads is kept within one-third to one-quarter of the span.     

Fatigue life estimation of steel using laser speckle sensor

We investigated a method to evaluate fatigue damage of steels without contact using a laser speckle sensor. In the earlier stage of fatigue in steels, slipbands are produced on the surface and the slipband density increases as fatigue damage progresses. When a laser illuminates the surface of the fatigued steel, light intensity distribution of the laser speckle pattern caused by the reflected light changes depending on the change of surface properties caused by slipbands. Width of the speckle pattern broadens correspondingly to spatial frequency distribution of the surface and thus it is presumed that speckle pattern broadens with increase of slipband density. The method presented in this paper is based on this phenomenon. In this study, we observed change of the speckle pattern during fatigue loading. We propose a method to estimate fatigue life by observing change in the speckle pattern depending on number of loading cycles in the earlier stage of fatigue before crack initiation.     

钢筋混凝土受压构件工作应力的测试与分析

在已建结构的可靠性评估中,结构当前的应力状态(工作应力状态)检测一直是较难解决的问题。对工程中常用工作应力测试方法进行了简要分析,提出利用钻孔-电测法测试钢筋混凝土受压构件的工作应力。该方法通过测试钻孔前后孔边应变的变化,利用钻取的芯样推定混凝土的抗压强度和弹性模量,再结合有限元计算分析,得到已建结构中钢筋混凝土受压构件的工作应力。试验结果表明,孔边实测的释放应变的数值与有限元计算的结果吻合良好,工作应力推定结果与试验结果基本一致,说明该方法可用于实际钢筋混凝土受压构件的工作应力测试。     

Source water quality effects on monochloramine inactivation of adenovirus, coxsackievirus, echovirus, and murine norovirus

There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and human adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log₁₀ reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log₁₀ CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log₁₀ CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans.     

国际海岸带规划管制研究与山东半岛的实践

尽管海岸带规划管制在国际上的开展已非常普遍,但在我国仍属新兴和前沿课题。结合笔者主持的多项山东半岛海岸带相关规划课题的研究成果,对国际海岸带规划管制发展的背景、管制方式和重要内容,以及沿海化压力下,山东半岛海岸带规划管制的解决之道做了解析和总结。     

Load combination effects on stress and strain concentration of completely overlapped tubular K(N)-joints

The stress and strain concentration of a completely overlapped tubular K(N) joint specimen under lap brace axial (AX), in-plane (IPB) and out-of-plane bending (OPB) is experimentally investigated. The combination effect of these loadings on the stress concentration of the joint is also studied. The test results showed that the maximum strain concentration factor of the joint under AX and OPB occurs at the saddle of through brace near the lap brace. For the joint under IPB, it occurs at the crown heel of lap brace. The peak hot spot stress (HSS) of the joint under combined loading is found occurred at a position between the crown and the saddle of members. A comparison of HSS showed that the equation proposed by Gulati et al. agrees reasonably well but the design recommendation, API RP2A, over predicts the test data. In the numerical analysis, the finite element model with 8-node thick shell element simulates very well the joint specimen. It is concluded that the existing equation for simple joints based on a superposition of stresses of basic load cases is suitable for predicting the stress concentration of completely overlapped tubular K(N)-joints under combined loading.     

土工格栅加筋对沥青路面影响的数值分析

应用复合材料力学原理和层状弹性体系理论对土工格栅沥青路面进行了力学分析。通过对计算结果中的应力、应变和位移分析,揭示了土工格栅的增强机理和防裂作用,同时还计算出加筋可以减薄路面厚度,而且 C-AC 层模量越大对加筋效果的影响越明显,但是同时也增大了基层底部的弯拉应力,可为路面设计提供参考。     

Virus removal by iron coagulation-microfiltration

This study was undertaken to determine virus removal efficiency by iron coagulation followed by microfiltration (MF) in water treatment using the MS2 bacteriophage (25 nm diameter) as a tracer virus. Results from these bench-scale studies were used to propose a mechanism for virus removal by iron coagulation–MF. Ferric chloride was used as coagulant, and the dosages were 0, 2, 5, and 10 mg/L as Fe(III) with pH adjusted during mixing to 6.3, 7.3 and 8.3. In the absence of iron-coagulation and with less than 2 mg/L Fe, MF alone achieved less than a 0.5 log removal of MS2 virus. However, iron-coagulation pretreatment dramatically improved virus removal, especially in the 5–10 mg/L Fe dose range, ultimately achieving more than 4-log removal at pH 6.3 with 10-mg/L Fe dose. For the 5 and 10 mg/L Fe dosages, decreasing pH in the 8.3–6.3 range resulted in significantly greater virus removal. For 0 and 2 mg/L iron dosages, decreasing pH in the 8.3–6.3 range also improved virus removal, but to a lesser extent. The experimental data indicates negatively charged MS2 viruses first adsorbed onto the positively charged iron oxyhydroxide floc particles before being removed by MF. MS2 viruses were not inactivated in iron or aluminum coagulation as evidenced by the fact that their concentrations before and after coagulation, settling, and re-suspension of the coagulated sludge were not statistically different.