Influence of weld misalignment and weld metal overmatch on the prediction of fracture in pipeline girth welds

$\text{J-}\text{integral}$ estimates using elastic-plastic finite element calculations, are shown to compare well with experimental results from single edge-notch bend (SENB) specimens made of X483 grade line pipe steel.The influence of weld misalignment and weld metal overmatch on fracture of cracked girth welds is predicted, also using elastic-plastic finite element calculations. Weld metal overmatch reduces plastic strain levels in the weld and appears beneficial in reducing $\text{J-}\text{integral}$ magnitudes. Predicted values of $\text{J-}\text{integral}$ are shown to increase with weld misalignment. However, $\text{J-}\text{integral}$ magnitudes near the critical value for crack growth initiation were only attained after considerable plastic straining at or near limit load. This result suggests that limit load calculations may be more appropriate for prediction of failure of cracked girth welds than conventional fracture techniques.     

Using precise data sets on farming and pesticide properties to verify a diffuse pollution hydrological model for predicting pesticide concentration.

Verification of a diffuse pollution model involves comparing results actually observed with those predicted by precise model inputs. Acquisition of precise model inputs is, however, problematic. In particular, when the target catchment is large and substantial estimation uncertainty exists, not only model verification but also prediction is difficult. Therefore, in this study, rice-farming data were collected for all paddy fields from all farmers in a catchment and pesticide adsorption and degradation rates in paddy field soil samples were measured to obtain precise model inputs. The model inputs successfully verified the model's capability to predict pesticide concentrations in river water. Sensitivity analyses of the model inputs elucidated the processes significantly affecting pesticide runoff from rice farms. Pesticide adsorption and degradation rates of the soil did not significantly affect pesticide concentrations, although pesticide discharge to river water accounted for less than 50% of the total quantity of pesticide applied to fields, possibly owing to pesticide adsorption and degradation. The timing of increases in pesticide concentrations in river water was affected mostly by the farming schedule, including the time of pesticide application and irrigation, and secondarily by rainfall events.     

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Preliminary Assessment of Contaminants in Soft Sediments of the Detroit River

Soft sediments from the Detroit River were analyzed for the USEPA priority pollutants to generally characterize contaminant distribution. Forty-three were detected. Highest heavy metal concentrations were found in the Trenton Channel and immediately downstream of Grosse Ile. They ranged from an area mean (N = 2) of 0.19 mg/kg mercury to 338.7 mg/kg zinc (dry weight). Polynuclear aromatic hydrocarbons ranged from 0.1 mg/kg to 38.8 mg/kg (mean, N = 2) with the highest levels near Grosse Ile. PCBs ranged from 0.015 mg/kg to 1.7 mg/kg (mean, N = 2). Organochlorine pesticides were not detected except for a trace of heptachlor in one sample. Sediment contamination in the Detroit River is widespread with higher concentrations on the U.S. side downstream of the Rouge River and in the Trenton Channel. The significance of these in-place pollutants to biota and as a source to Lake Erie is still unknown.     

Zinc and Phytate Distribution in Peas. Influence of Heat Treatment, Germination, pH, Substrate, and Phosphorus on Pea Phytate and Phytase

The largest proportions of zinc and phytate, 88.7 and 97.1%, respectively, were in the Garfield pea cotyledon; the greatest concentrations were in the germ. Cooking peas by two different methods resulted in 13% phytate reduction. Peas incubated 6.5 hr from 25 to 80°C yielded maximum phytate loss (25%) at 60°C due to phytase activated hydrolysis. Germination (10 d) decreased pea phytate 75% and increased phytase activity 12-fold. Semi-purified germinated pea phytase showed temperature optimum at 45°C, pH optimum of 5.2, 30% inhibition by 1 mM inorganic P, and substrate preference for pyrophosphate. Incubation of early germinated peas at optima pH and temperature is suggested for maximum phytate reduction.     

The effects of stress and crack morphology on time-of-flight diffraction signals

A model based on the theory of infinite contacting surfaces is used to analyse the transmission and reflection of ultrasound at tight fatigue cracks under compressive stress. The model developed is valid for both compression and shear (SV) waves incident at arbitrary angles on a fatigue crack and includes mode conversion effects. In discussing diffraction of ultrasound by the tips of finite length fatigue cracks, we associate the amplitude of the diffracted signal with the strength of the signal reflected from cracks of infinite extent. Thus we allow all the energy transmitted by the tight crack to play no part in the diffraction process. Comparison is made with experiments carried out at Harwell and we conclude that, for these particular experiments, the cracks are fully open when subjected to about 88 MPa of tension, and that the experimental results are consistent with a root mean square deviation from flatness of the crack faces of about 1·5 μm. This is in broad agreement with the actual crack profile when a sampling length of about 30 μm is used. Using these values the theory and experiment show excellent agreement to within 2 dB over the whole applied stress range. The results show, for example, a diffraction signal decreased by a maximum of about 13 dB when the applied compressive load corresponds to 70% of the maximum load used during crack growth. Similar conclusions are also drawn for conventional pulse-echo inspection, whereas Tandem suffers a greater reduction in signal strength due to the usually lower frequency.