Removal of colloids from sewage

Reprint. Originally published: The Illinois engineer (April and May, 1928)

Estimating uncertainty when using transient data in steady-state calculations

This paper was accepted for publication in the journal Measurement and the definitive published version is available at http://dx.doi.org/10.1016/j.measurement.2016.07.084.When using measurement data for monitoring there is often a desire for steady-state analysis. On-line condition monitoring and fault detection systems are typical applications where the traditional way of treating transient data is to remove it using methods that require tuning using thresholds. This paper suggests an alternative approach where the uncertainty estimate in a particular variable is increased in response to the presence of transients and through propagation, varies the uncertainty in the result accordingly. The formulation of the approach is described and applied to two examples from building HVAC systems. The approach is demonstrated to be a pragmatic tool that can be used to increase the robustness of calculations from time series data

Uncertainty in the first principle model based condition monitoring of HVAC systems

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN052916 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Developments in construction-scale additive manufacturing processes

Additive manufacturing in construction is beginning to move from an architect's modelling tool to delivering full-scale architectural components and elements of buildings such as walls and facades. This paper discusses large-scale additive manufacturing processes that have been applied in the construction and architecture arena and focuses on ‘Concrete Printing’, an automated extrusion based process. The wet properties of the material are critical to the success of manufacture and a number of new criteria have been developed to classify these process specific parameters. These criteria are introduced and key challenges that face construction scale additive manufacturing are presented

Hardened properties for high-performance printing concrete

This paper presents the hardened properties of a high-performance fibre-reinforced fine-aggregate concrete extruded through a 9 mm diameter nozzle to build layer-by-layer structural components in a printing pro- cess. The printing process is a digitally controlled additive method capable of manufacturing architectural and structural components without formwork, unlike conventional concrete construction methods. The effects of the layering process on density, compressive strength, flexural strength, tensile bond strength and drying shrinkage are presented together with the implication for mix proportions. A control concrete (mould-cast specimens) had a density of approximately 2250 kg/m3, high strength (107 MPa in compression, 11 MPa in flexure) and 3 MPa in direct tension, together with a relatively low drying shrinkage of 175 μm (cured in water) and 855 μm (cured in a chamber at 20 °C and 60% relative humidity) at 184 days. In contrast well printed concrete had a density of 2350 kg/m3, compressive strength of 75–102 MPa, flexural strength of 6–17 MPa depending on testing direction, and tensile bond strength between layers varying from 2.3 to 0.7 MPa, reducing as the printing time gap between layers increased. The well printed concrete had signifi- cantly fewer voids greater than 0.2 mm diameter (1.0%) when compared with the mould-cast control (3.8%), whilst samples of poorly printed material had more voids (4.8%) mainly formed in the interstices be- tween filaments. The additive extrusion process was thus shown to retain the intrinsic high performance of the material