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Zhang H.,University of Nottingham | Zhang H.,WRc Plc. | Zanchetta P.,University of Nottingham | Bradley K.J.,University of Nottingham | Gerada C.,University of Nottingham
IEEE Transactions on Industry Applications | Year: 2010

This paper presents a novel low-intrusion load and efficiency evaluation method for in-service induction motors based on vibration measurements. This method enhances the traditional vibration analysis by providing motor load and efficiency information in addition to the mechanical health information. The application is in multimotor plants, where individual motor monitoring is too expensive to implement yet where motor operating conditions need to be known to work at improved plant efficiency. The vibration signature of the machine, measured by an accelerometer and processed by fast Fourier transform (FFT) is used to extract frequencies defining shaft speed and the supply frequency. This data, in conjunction with the basic motor performance data, enables the determination of the actual load and indirectly, the efficiency which the motor is operating at. For motors supplied form a variable-speed drive (VSD), the loss segregation method is used to yield the motor losses indirectly and thus, the efficiency. © 2010 IEEE. Source


O'Donoghue N.,Queens University of Belfast | O'Donoghue N.,WRc Plc. | Phillips D.H.,Queens University of Belfast | Nicell C.,House of Control
Water Environment Research | Year: 2015

The advancement of telemetry control for the water industry has increased the difficulty of managing large volumes of nuisance alarms (i.e., alarms that do not require a response). The aim of this study was to identify and reduce the number of nuisance alarms that occur for Northern Ireland (NI) Water by carrying out alarm duration analysis to determine the appropriate length of persistence (an advanced alarm management tool) that could be applied. All data were extracted from TelemWeb (NI Water's telemetry monitoring system) and analyzed in Excel. Over a 6-week period, an average of 40 000 alarms occurred per week. The alarm duration analysis, which has never been implemented before by NI Water, found that an average of 57% of NI Water alarms had a duration of ,5 minutes. Applying 5-minute persistence, therefore, could prevent an average 26 816 nuisance alarms per week. Most of these alarms were from wastewater assets. Source


Williams J.B.,University of Portsmouth | Clarkson C.,University of Portsmouth | Mant C.,University of Portsmouth | Drinkwater A.,WRc Plc. | May E.,University of Portsmouth
Water Research | Year: 2012

Fat, oil and grease deposits (FOG) in sewers are a major problem and can cause sewer overflows, resulting in environmental damage and health risks. Often simplistically portrayed as cooling of fats, recent research has suggested that saponification may be involved in FOG formation. However there are still questions about the mechanisms effecting transformations in sewers and the role and source of metal cations involved in saponification. This study characterises FOG deposits from pumping stations, sewers and sewage works from different water hardness zones across the UK. The sites all had previous problems with FOG and most catchments contained catering and food preparation establishments. The FOG deposits were highly variable with moisture content ranging from 15 to 95% and oil content from 0 to 548 mg/g. Generally the pumping stations had lower moisture content and higher fat content, followed by the sewers then the sewage works. The water in contact with the FOG had high levels of oil (mean of about 800 mg/L) and this may indicate poor kitchen FOG management practices. FOG fatty acid profiles showed a transformation from unsaturated to saturated forms compared to typical cooking oils. This seems to relate to ageing in the sewer network or the mechanism of formation, as samples from pumping stations had higher proportions of C18:1 compared to C16. This may be due to microbial transformations by bacteria such as Clostridium sp. in a similar process to adipocere formation. There was an association between water hardness and increased Ca levels in FOG along with harder deposits and higher melting points. A link between FOG properties and water hardness has not been previously reported for field samples. This may also be due to microbial processes, such as biocalcification. By developing the understanding of these mechanisms it may be possible to more effectively control FOG deposits, especially when combined with promotion of behavioural change. © 2012 Elsevier Ltd. Source


Doncaster C.P.,University of Southampton | Davey A.J.H.,WRc Plc. | Dixon P.M.,Iowa State University
Environmental and Ecological Statistics | Year: 2014

Estimation of design power requires knowledge of treatment effect size and error variance, which are often unavailable for ecological studies. In the absence of prior information on these parameters, investigators can compare an alternative to a reference design for the same treatment(s) in terms of its precision at equal sensitivity. This measure of relative performance calculates the fractional error variance allowed of the alternative for it to just match the power of the reference. Although first suggested as a design tool in the 1950s, it has received little analysis and no uptake by environmental scientists or ecologists. We calibrate relative performance against the better known criterion of relative efficiency, in order to reveal its unique advantage in controlling sensitivity when considering the precision of estimates. The two measures differ strongly for designs with low replication. For any given design, relative performance at least doubles with each doubling of effective sample size. We show that relative performance is robustly approximated by the ratio of reference to alternative α quantiles of the F distribution, multiplied by the ratio of alternative to reference effective sample sizes. The proxy is easy to calculate, and consistent with exact measures. Approximate or exact measurement of relative performance serves a useful purpose in enumerating trade-offs between error variance and error degrees of freedom when considering whether to block random variation or to sample from a more or less restricted domain. © 2013 Springer Science+Business Media New York. Source


McGrath S.P.,Rothamsted Research | Chambers B.J.,ADAS Gleadthorpe | Taylor M.J.,ADAS Gleadthorpe | Carlton-Smith C.H.,WRc Plc.
Plant and Soil | Year: 2012

Background and aims: Increasing the concentrations of the essential micronutrient Zn in staple crops like grain is desirable for human nutrition. We investigated the long-term ability of municipal treatment works sewage sludge, liquid sewage sludge and ZnCO3 applied to soils to increase Zn in in wheat grain (Triticum aestivum L.) in a number of field experiments conducted on different soils. Methods: We used six long-term field experiments that were set up on contrasting soils in England and the target applications were built up between 1994 and 1997. Topsoil samples and harvested grain samples were taken and air dried in 1999, 2001, 2003 and 2005. Relationships between grain Zn concentrations and soil properties and changes with time were examined. Results: Wheat grain Zn concentrations increased with soil Zn concentrations in a similar log-log relationship with all of the Zn sources tested. Comparing total or extractable Zn in soil as explanatory factors showed little benefit of using extractable Zn measurements to predict grain concentrations over total Zn. Additional factors such as soil pH or organic carbon did not explain much more of the variation in grain Zn in our experiments. However, grain Zn concentrations did not respond at all at a site with pH 7. 7. Conclusions: Sewage sludge applications to soil can increase grain Zn concentrations for at least 2 to 8 years after application and has similar effectiveness to ZnCO3. © 2012 Springer Science+Business Media B.V. Source

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