Residual stress and constraint effects on cleavage fracture in the transition temperature regime

Defects in structural components are often associated with welds that may contain significant levels of residual stress. Whilst the primary load acting on the component may induce low constraint conditions at the crack tip, the presence of residual stresses, e.g. due to welding, can modify this constraint level and consequently influence the observed fracture toughness behaviour. This paper presents the results of a combined experimental and numerical programme aimed at exploring this issue. Cleavage fracture toughness data for high and low constraint specimens are presented with and without residual stresses. The results indicate that under certain conditions, the constraint-induced increase in cleavage fracture toughness may be eroded by the presence of a residual stress in the vicinity of the crack. The results are quantified with respect to two-parameter fracture mechanics in which the  T  and  Q  parameters are appropriately defined. Preliminary guidance is provided for the assessment of defects when residual stresses may influence crack-tip constraint.     

水冷分离式制冷系统在工程中的适用范围

对水冷分离式制冷系统进行了初步分析，并结合工程实例与水冷式冷水主机制冷系统进行比较，尝试找出其在工程中的适用范围。     

MODELING ON THE CYCLIC OPERATION OF STANDING COLUMN WELLS UNDER REGIONAL GROUNDWATER FLOW

Coupled hydrogeological-thermal simulation of the Standing Column Well(SCW) system is essential to provide an optimized configuration and operation schedule for boreholes on the site.This paper presents numerical investigations and thermo-hydraulic evaluation of standing column well system operating under cyclic flow regime.A three-dimensional numerical model for groundwater flow and heat transport is used to analyze the heat exchange in the ground.The model includes the effects of convective and conductive...     

NUMERICAL SIMULATION OF SKIMMING FLOW OVER MILD STEPPED CHANNEL

1. INTRODUCTION The stepped channel/spillway finds its extensiveapplications in hydraulic and environmentalengineering, which is used to dissipate the energy ofreleased flood and also to be a landscape structure.Flow over the stepped channel/spillway is a…     

Heat-Shocked Lactobacilli for Acceleration of Cheddar Cheese Ripening

The aim of this study was to establish adequate conditions for heat-shocking cells of lactobacilli, to sufficiently suppress lactic acid production without damaging the proteolytic enzyme system important for cheese maturation. Three temperatures, 65, 67 and 70°C were tested, for 22 sec. The best combination for maximum retardation of lactic acid production and minimum damage to the proteolytic system was obtained by treating cells at 67°C for 22 sec. Following such treatment, lactic acid production was retarded by 24 hr, while the proteolytic enzyme system remained scarcely unchanged.     

Impact of Soy Protein Isolates and Specific Fractions on Rancidity Development in a Cooked, Refrigerated Beef System

Adding 0, 8, 16 and 24% soy isolate to a cooked, refrigerated beef system decreased TBA values proportionately. The impact of specific crude soy protein fractions on development of rancidity (TBA values) was investigated. The 7S, 9S and 11S protein fractions, a whole protein isolate produced from the same flakes, and the same commercial soy isolate as used previously were incorporated at the 24% or equivalent level. All additions had significant (P<0.05) antioxidant effect. The commercial isolate and the laboratory-produced whole isolate exhibited the most antioxidant activity. The 7S and the 9S fractions contributed significant (P<0.05) antioxidant activity.