Correlations between rail wear rates and operating conditions in a commercial railroad

The rail wear rates per traffic unit (mm/MTon) in the curves of a 4.5 km-long commercial line over a period of 9 years were measured and related to specific operation conditions. The rail corrugation was analyzed using a Corrugation Analysis Trolley (CAT) and visual inspection was carried out in order to identify the defects in the railroad. Since Rolling Contact Fatigue (RCF), artificial abrasion and corrugation were found to be the most important issues the grinding procedures used during maintenance of the railroad were evaluated to assess their effectiveness on removing the defects from the rail surface. The results showed that the wear rates in the studied railroad were several times higher than those typically found in the literature, mainly as a consequence of inappropriate grinding regimes. White layer formation and only partial removal of cracks emerged as the most relevant drawbacks of rail grinding procedures

Axlebox accelerations: Their acquisition and time frequency characterisation for railway track monitoring purposes

[EN] Railway track maintenance is becoming a real challenge for Railway Engineers due to the need of meeting increasingly high quality requirements by means of cost-effective procedures. Frequently, this can be only achieved by implementing some technological developments from other fields into the railway sector, such as Digital Signal Processing. Indeed, the present work delves into data acquisition and processing techniques in order to enhance track surveying processes. For this purpose, run tests on the Metropolitan Rail Network of Valencia (Spain) were carried out, and axlebox accelerations were gathered and analysed in different ways. The results determined the optimal sampling and filtering frequencies as well as the location of accelerometers along the train. Furthermore, by means of spectral analysis and time frequency representations, diverse track defects, track singularities and vibration modes can be clearly identified. It is shown how, with a Hamming time window of 0.5 s and an overlapping of 95%, a wide set of track defects can be detected, without the need of complementary analyses. These values yield the best results as they are a good compromise between time and frequency resolution and allow for appropriate pattern recognition of the corresponding track singularities and resonant frequencies.Project Funded by Geoconcept Co. Ltd. and the Spanish Ministry of Economy and Competitiveness. Ref. IDI-20110461.Salvador Zuriaga, P.; Naranjo Ornedo, V.; Insa Franco, R.; Teixeira, P. (2016). Axlebox accelerations: Their acquisition and time frequency characterisation for railway track monitoring purposes. Measurement. 82:301-312. doi:10.1016/j.measurement.2016.01.012S3013128

Benefits and Drawbacks of Pre-licensure Clinical Jobs in Undergraduate Nursing Students

This research study aims to identify the benefits and drawbacks of pre-licensure clinical jobs in undergraduate nursing students. Many nursing students are encouraged to have a job in clinical settings in order to gain more experience. Many undergraduate nursing students here at the University of Akron currently have jobs in the clinical setting and these are the student\u27s who we plan to use as our sample for this study. This study will be completed by spring of 2023, before graduation

Active habitat selection by Capitella sp. I larvae. I. Two-choice experiments in still water and flume flow

Sediment selection by settling larvae of the opportunistic polychaete Capitella sp. I was determined in laboratory still-water and flume experiments, where larvae were given a choice between two highly contrasting sediment treatments. In most cases, 2-h experiments were conducted with a natural, organic-rich mud and an abiotic, glass-bead mixture with a grain-size distribution similar to the mud, as the sediment treatments. Spatial settlement patterns were also determined in sediment arrays containing mud only. Two types of flume flows were tested, both with a near-surface velocity of ∼5 cm s−1, but one flow was cyclical, varying between about 2 and 7 cm s−1 with a period of 6.3 min, and one was steady with a boundary shear velocity of 0.26 cm s−1. Plastic spheres were added to the experiments as passive larval mimics. Capitella sp. I larvae selected the muddy sediment as opposed to the glass beads in all experiments conducted, consistent with food requirements of the deposit-feeding adults and with field distributions. Selectivity was insensitive to a range of experimental conditions, including flow, water temperature, light regime, experimental duration, distance sediment treatments were separated, time of year and larval batch. Experiments furthermore suggested that contact with the sediment is required to elicit a settlement response. Flows tested were weak compared to the range likely encountered by larvae of this species, even in depositional areas in the field; however, horizontal flow speeds within larval search distances of the bottom exceeded horizontal swim speeds of the larvae (determined in still water). A model for sediment selection in the field is proposed where larvae move up and down close to the bottom, while being transported by the flow, and test sediments on contact. Selection is thus accomplished by active acceptance or rejection of touchdown sites. This model was qualitatively supported by observations of larvae in still water and manipulative flume experiments. These results suggest that active sediment selection may be responsible, at least in part, for field distributions of this species