Grain boundary microstructure and fatigue crack growth in Allvac 718Plus superalloy

The correlation between grain boundary microstructure and fatigue crack growth with hold-times was investigated for two conditions of the superalloy Allvac 718Plus; a Standard condition with the recommended distribution of grain boundary phases and a Clean condition with virtually no grain boundary phases. Fatigue testing was performed at 704 degrees C using 10 Hz cyclic load with intermittent hold-times of 100 s at maximum tensile load. Microstructural characterization and fractography were conducted using scanning- and transmission electron microscopy techniques. Auger electron- and X-ray photoelectron spectroscopy techniques were used for oxide analyses on fracture surfaces. It was found that in the Standard condition crack growth is mostly transgranular for 10 Hz loading and intergranular for hold-times, while for the Clean condition crack growth is intergranular in both load modes. The lower hold-time crack growth rates in the Standard condition are attributed to grain boundary delta-phase precipitates. No effect of delta-phase was observed for 10 Hz cyclic loading crack growth rates. Two different types of oxides and oxide colours were found on the fracture surfaces in the Standard condition and could be correlated to the different loading modes. For cyclic loading a bright thin Cr-enriched oxide was dominate and for hold-times a dark and slightly thicker Nb-enriched oxide was dominant These oxide types could be related to the oxidation of delta-phase and the matrix respectively. The influence of delta-phase precipitates on crack propagation is discussed

Division of overall duration of stay into operative stay and postoperative stay improves the overall estimate as a measure of quality of outcome in burn care.

PATIENTS AND METHODS:Surgically managed burn patients admitted between 2010-14 were included. Operative stay was defined as the time from admission until the last operation, postoperative stay as the time from the last operation until discharge. The difference in variation was analysed with F-test. A retrospective review of medical records was done to explore reasons for extended postoperative stay. Multivariable regression was used to assess factors associated with operative stay and postoperative stay. RESULTS:Operative stay/TBSA% showed less variation than total duration/TBSA% (F test = 2.38, p<0.01). The size of the burn, and the number of operations, were the independent factors that influenced operative stay (R2 0.65). Except for the size of the burn other factors were associated with duration of postoperative stay: wound related, psychological and other medical causes, advanced medical support, and accommodation arrangements before discharge, of which the two last were the most important with an increase of (mean) 12 and 17 days (p<0.001, R2 0.51). CONCLUSION:Adjusted operative stay showed less variation than total hospital stay and thus can be considered a more accurate outcome measure for surgically managed burns. The size of burn and number of operations are the factors affecting this outcome measure

Female risk-adjusted survival advantage after injuries caused by falls, traffic or assault : a nationwide 11-year study

Background A female survival advantage after injury has been observed, and animal models of trauma have suggested either hormonal or genetic mechanisms as component causes. Our aim was to compare age and risk-adjusted sex-related mortality in hospital for the three most common mechanisms of injury in relation to hormonal effects as seen by age. Methods All hospital admissions for injury in Sweden during the period 2001-2011 were retrieved from the National Patient Registry and linked to the Cause of Death Registry. The International Classification of Diseases Injury Severity Score (ICISS) was used to adjust for injury severity, and the Charlson Comorbidity Index to adjust for comorbidity. Age categories (0-14, 15-50, and 51years) were used to represent pre-menarche, reproductive and post- menopausal women. Results Women had overall a survival benefit (OR 0.51; 95% CI 0.50 to 0.53) after adjustment for injury severity and comorbidity. A similar pattern was seen across the age categories (0-14years OR 0.56 (95% CI 0.25 to 1.25), 15-50years OR 0.70 (95% CI 0.57 to 0.87), and 51years OR 0.49 (95% CI 0.48 to 0.51)). Conclusion In this 11-year population-based study we found no support for an oestrogen-related mechanism to explain the survival advantage for females compared to males following hospitalisation for injury

Reflection-Based Source Inversion for Sparse Imaging of Low-Loss Composite Panels

This article presents a bistatic reflection-based imaging technique for electromagnetic testing of conductor-backed composite panels, which is based on an inverse formulation of the numerical problem at hand, and technically extends a previously demonstrated transmission-based system. The technique exploits the a priori assumption of pixel-based sparsity and retrieves the final image using data from only a single measurement, thereby removing the necessity of a reference measurement to be conducted. To demonstrate the capability of the technique, retrieved images are presented for a synthetic proof-of-concept device under test and an industrially manufactured composite panel. The presented technique can be considered as the initial model in the development of more complex bistatic imaging systems and has been developed for the purpose of extending the opportunities to conduct reflection-based electromagnetic nondestructive testing on aircraft structural components

Compressive Sensing Techniques for mm-Wave Non-Destructive Testing of Composite Panels

This paper presents imaging results from measurements of an industrially manufactured composite test panel, utilizing two introduced algorithms for data post-processing. The system employs a planar near-field scanning set-up for characterizing defects in composite panels in the 50&#x2013;67 GHz band, and can be considered as a complementary diagnostic tool for non-destructive testing purposes. The introduced algorithms are based on the reconstruction of the illuminating source at the transmitter, enabling a separation of the sampled signal with respect to the location of its potential sources&#x003B; the scatterers within the device under test or the transmitter. For the second algorithm, a L1-minimization problem formulation is introduced that enables compressive sensing techniques to be adapted for image retrieval. The algorithms are benchmarked against a more conventional imaging technique, based on the Fourier Transform, and it is seen that the complete imaging system provides increased dynamic range, improved resolution and reduced measurement time by removal of a reference measurement. Moreover, the system provides stable image quality over a range of frequencies

Decreased risk adjusted 30-day mortality for hospital admitted injuries : a multi-centre longitudinal study

Background: The interpretation of changes in injury-related mortality over time requires an understanding of changes in the incidence of the various types of injury, and adjustment for their severity. Our aim was to investigate changes over time in incidence of hospital admission for injuries caused by falls, traffic incidents, or assaults, and to assess the risk-adjusted short-term mortality for these patients. Methods: All patients admitted to hospital with injuries caused by falls, traffic incidents, or assaults during the years 2001-11 in Sweden were identified from the nationwide population-based Patient Registry. The trend in mortality over time for each cause of injury was adjusted for age, sex, comorbidity and severity of injury as classified from the International Classification of diseases, version 10 Injury Severity Score (ICISS). Results: Both the incidence of fall (689 to 636/100000 inhabitants: p = 0.047, coefficient -4.71) and traffic related injuries (169 to 123/100000 inhabitants: p &lt; 0.0001, coefficient -5.37) decreased over time while incidence of assault related injuries remained essentially unchanged during the study period. There was an overall decrease in risk-adjusted 30-day mortality in all three groups (OR 1.00; CI95% 0.99-1.00). Decreases in traffic (OR 0.95; 95% CI 0.93 to 0.97) and assault (OR 0.93; 95% CI 0.87 to 0.99) related injuries was significant whereas falls were not during this 11-year period. Discussion: Risk-adjustment is a good way to use big materials to find epidemiological changes. However after adjusting for age, year, sex and risk we find that a possible factor is left in the pre-and/or in-hospital care. Conclusions: The decrease in risk-adjusted mortality may suggest changes over time in pre-and/or in-hospital care. A non-significantdecrease in risk-adjusted mortality was registered for falls, which may indicate that low-energy trauma has not benefited for the increased survivability as much as high-energy trauma, ie traffic-and assault related injuries