Peritectic Behavior Detection in the Fe-C-Mn-Al-Si Steel System using Fiber Optic Temperature Mapping

Peritectic reactions can cause surface defects and breakouts in continuous casting and the peritectic region is often avoided by adjusting the chemical composition of the steel to cast outside of the peritectic sensitivity range. However, the combined effects of C, Mn, Al, and Si on the boundaries that map peritectic region are still disputed for many advanced high strength steel grades. An apparatus for performing controlled solidification experiments is being developed to characterize the effects of chemical composition on the uniformity of shell growth during solidification using a copper chill mold with an embedded fiber-optic temperature sensor that enables high spatial resolution temperature mapping. The spatially distributed fiber-optic sensor employs optical frequency domain reflectometry to measure temperatures with a 0.6mm spatial resolution along the length of the fiber at a 20ms sampling rate to map closely spaced temperature features caused by the peritectic reaction. This paper reports progress on the ongoing efforts to develop a peritectic sensing system using optical fiber temperature sensing technology

A Spatially Distributed Fiber-Optic Temperature Sensor for Applications in the Steel Industry

This paper presents a spatially distributed fiber-optic sensor system designed for demanding applications, like temperature measurements in the steel industry. The sensor system employed optical frequency domain reflectometry (OFDR) to interrogate Rayleigh backscattering signals in single-mode optical fibers. Temperature measurements employing the OFDR system were compared with conventional thermocouple measurements, accentuating the spatially distributed sensing capability of the fiber-optic system. Experiments were designed and conducted to test the spatial thermal mapping capability of the fiber-optic temperature measurement system. Experimental simulations provided evidence that the optical fiber system could resolve closely spaced temperature features, due to the high spatial resolution and fast measurement rates of the OFDR system. The ability of the fiber-optic system to perform temperature measurements in a metal casting was tested by monitoring aluminum solidification in a sand mold. The optical fiber, encased in a stainless steel tube, survived both mechanically and optically at temperatures exceeding 700◦C. The ability to distinguish between closely spaced temperature features that generate information-rich thermal maps opens up many applications in the steel industry

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe