Determination of the rheological parameters of self-compacting concrete matrix using slump flow test

The classification of a concrete mixture as self-compacting (SCC) is performed by a series of empirical characterization tests that have been designed to assess not only the flowability of the mixture but also its segregation resistance and filling ability. The objective of the present work is to correlate the rheological parameters of SCC matrix, yield stress and plastic viscosity, to slump flow measurements. The focus of the slump flow test investigation was centered on the fully yielded flow regime and an empirical model relating the yield stress to material and flow parameters is proposed. Our experimental data revealed that the time for a spread of 500 mm which is used in engineering practice as reference for measurement parameters, is an arbitrary choice. Our findings indicate that the non-dimensional final spread is linearly related to the non-dimensional yield-stress. Finally, there are strong indications that the non-dimensional viscosity of the mixture is associated with the non-dimensional final spread as well as the stopping time of the slump flow; this experimental data set suggests an exponential decay of the final spread and stopping time with viscosity. © Appl. Rheol.

Trial Test of a Bulk-Type Fully HTS Synchronous Motor

© 2013 IEEE. The world's first bulk-type fully high temperature superconducting synchronous motor (HTS-SM) was assembled and tested in our laboratory at the University of Cambridge. The fully HTS-SM was designed with 75 Y123 HTS bulks mounted on the surface of the rotor and six air core 2G HTS racetrack coils used for stator windings. We successfully applied a light fan load test for this fully HTS-SM at its operating temperature of 77 K. The detected decay of the trapped magnetic flux densities at the centre of the HTS bulks was up to 16.5% after 5 h of synchronous rotation. Due to the high current density of the HTS material, the ac stator field for the 2G HTS winding was 49.2% stronger compared with a comparable copper winding. In the meantime, we estimated that the efficiency was about 86% potentially under stable low frequency rotation at 150 r/min. The results show that the performance of this HTS motor is acceptable for practical applications.

A preliminary study on methods for retaining data quality problems in automatically generated test data

Data in an organisation often contains business secrets that organisations do not want to release. However, there are occasions when it is necessary for an organisation to release its data such as when outsourcing work or using the cloud for Data Quality (DQ) related tasks like data cleansing. Currently, there is no mechanism that allows organisations to release their data for DQ tasks while ensuring that it is suitably protected from releasing business related secrets. The aim of this paper is therefore to present our current progress on determining which methods are able to modify secret data and retain DQ problems. So far we have identified the ways in which data swapping and the SHA-2 hash function alterations methods can be used to preserve missing data, incorrectly formatted values, and domain violations DQ problems while minimising the risk of disclosing secrets. © (2012) by the AIS/ICIS Administrative Office All rights reserved.