Use of Mechanical and Metallurgical Analysis to Evaluate Cause of Fractures in a Cast 310 Stainless Steel Pintle Chain

A pintle chain composed of a cast 310 stainless steel material experienced embrittlement, deformation, and multiple fractures after operating six months inside a furnace. The design is such that the chain travels the length of the furnace, experiencing temperatures cycling between ambient and 1,700?F in an oxidizing atmosphere. Pins comprising the individual chain links had experienced deformation, and in some cases, had also fractured in a brittle manner. The links comprising the chain had also experienced numerous fractures in a brittle manner. An analysis of the loads experienced by the pins and links determined that both the short-term yield strength and the long-term creep strength of the pins had been exceeded at the normal operating temperature of the furnace. Furthermore, metallurgical analysis of the pins and links determined that carburization had taken place, embrittling the pins and links. A change to the original design of the furnace had resulted in the unintended presence of the carburizing atmosphere inside the furnace during the first 6?months of operation. The carburizing atmosphere was alleviated by returning to the original furnace design. Upgrading the alloy selection for the chain provided further resistance to service-related embrittlement, increased ductility when cycling to ambient temperature, and increased high temperature strength. Increasing the size of the links and pins was recommended (an upgrade to a higher chain load rating), but was not practical, given the dimensional constraints of running the chain in the furnace.     

Predictive Thermal Inactivation Model for Effects and Interactions of Temperature, NaCl, Sodium Pyrophosphate, and Sodium Lactate on Listeria monocytogenes in Ground Beef

The effects and interactions of heating temperature (60 °C to 73.9 °C), salt (0.0 % to 4.5 %?w/v), sodium pyrophosphate (0.0 % to 0.5 %?w/v), and sodium lactate (0.0 % to 4.5 %?w/v) on the heat resistance of a five-strain mixture of Listeria monocytogenes in 75 % lean ground beef were examined. Meat samples in sterile filtered stomacher bags were heated in a temperature controlled waterbath to determine thermal death times. The recovery medium was tryptic soy agar supplemented with 0.6 % yeast extract and 1 % sodium pyruvate. Weibull survival functions were employed to model the primary survival curves. Then, survival curve-specific estimated parameter values obtained from the Weibull model were used for determining a secondary model. The results indicate that temperature and salt have a large impact on the inactivation kinetics of L. monocytogenes, while sodium lactate (NaL) has an impact in the presence of salt. The model presented in this paper for predicting inactivation of L. monocytogenes can be used as an aid in designing lethality treatments meant to control the presence of this pathogen in ready-to-eat products.     

Managing information and supplies inventory operations in a manufacturing environment. Part 2: An order-timing and sizing algorithm

We develop a new, flexible independent demand forecasting-optimisation algorithm, and apply it to nine difficult-to-manage maintenance and repair products at the AREVA nuclear fuel rod manufacturing facility. The algorithm results in a 27% reduction in inventory holding and ordering costs relative to AREVA's baseline ERP method. This is in addition to improving the line item fill rates from 96 to 98%. This new algorithm is more flexible than the baseline method in that (1) our forecast error distribution is not assumed to be normal—we automatically find the best-fitting distribution from a large family of distributions, (2) we jointly optimise the order quantity and reorder point by using an optimisation routine that is embedded in a simulation methodology. Our algorithm can therefore handle a non-stationary demand process during the planning horizon, and (3) we dynamically select the best time series forecaster for demand based on the most recent history. This flexibility drove the performance improvements. Our algorithm can be easily adapted to any independent demand situation across any industry's supply chain.     

Understanding workplace violence: The value of a systems perspective

Workplace violence is a leading form of occupational injury and fatality, but has received little attention from the ergonomics research community. The paper reports findings from the 2012 New Zealand Workplace Violence Survey, and examines the workplace violence experience of 86 New Zealand organisations and the perceptions of occupational health and safety professionals from a systems perspective. Over 50% of respondents reported violence cases in their organisation, with perpetrators evenly split between co-workers and external sources such as patients. Highest reported levels of violence were observed for agriculture, forestry and construction sectors. Highest risk factor ratings were reported for interpersonal and organisational factors, notably interpersonal communication, time pressure and workloads, with lowest ratings for environmental factors. A range of violence prevention measures were reported, although most organisations relied on single control measures, suggesting unmanaged violence risks were common among the sample.     

Calibration and validation of a solar thermal system model in Modelica

Recent advancements in the domain of modeling physical processes offer opportunities to use equation based modeling environments, such as Modelica, for the simulation of building heating, ventilation, and air-conditioning (HVAC) systems. The current work demonstrates Modelica capabilities in a case study of real building solar thermal system simulation. The simulated system is part of an innovative ENERGYbase building, designed according to the so called Passivhaus standard. Model calibration and validation procedure is developed to include optimization based parametric adjustments of component models using the monitoring data during a single week. The calibrated system adequately reproduces half a year of real system operation. Future work will concentrate on application of the developed calibration and validation methodology in the whole year overall building energy simulation.