Damien Maher

Remote Real-Time Monitoring of Subsurface Landfill Gas Migration

The cost of monitoring greenhouse gas emissions from landfill sites is of major concern for regulatory authorities. The current monitoring procedure is recognised as labour intensive, requiring agency inspectors to physically travel to perimeter borehole wells in rough terrain and manually measure gas concentration levels with expensive hand-held instrumentation. In this article we present a cost-effective and efficient system for remotely monitoring landfill subsurface migration of methane and carbon dioxide concentration levels. Based purely on an autonomous sensing architecture, the proposed sensing platform was capable of performing complex analytical measurements in situ and successfully communicating the data remotely to a cloud database. A web tool was developed to present the sensed data to relevant stakeholders. We report our experiences in deploying such an approach in the field over a period of approximately 16 months.

An insight into linear quarter car model accuracy

The linear quarter car model is the most widely used suspension system model. A number of authors expressed doubts about the accuracy of the linear quarter car model in predicting the movement of a complex nonlinear suspension system. In this investigation, a quarter car rig, designed to mimic the popular MacPherson strut suspension system, is subject to narrowband excitation at a range of frequencies using a motor driven cam. Linear and nonlinear quarter car simulations of the rig are developed. Both isolated and operational testing techniques are used to characterise the individual suspension system components. Simulations carried out using the linear and nonlinear models are compared to measured data from the suspension test rig at selected excitation frequencies. Results show that the linear quarter car model provides a reasonable approximation of unsprung mass acceleration but significantly overpredicts sprung mass acceleration magnitude. The nonlinear simulation, featuring a trilinear shock absorber model and nonlinear tyre, produces results which are significantly more accurate than linear simulation results. The effect of tyre damping on the nonlinear model is also investigated for narrowband excitation. It is found to reduce the magnitude of unsprung mass acceleration peaks and contribute to an overall improvement in simulation accuracy.

In situ monitoring of environmental water quality using an autonomous microfluidic sensor

An autonomous microfluidic sensor for phosphate in environmental waters has been developed and assessed in laboratory and field trials. The sensor is based on the molybdenum yellow method for phosphate detection in which a phosphate-containing sample is mixed with a reagent containing ammonium molybdate and ammonium metavanadate in an acidic medium. The yellow-colored compound which is formed absorbs strongly below 400nm and its absorbance is proportional to the concentration of phosphate in the original sample. The sensor utilizes a microfluidic manifold where mixing, reaction and detection take place. Optical detection is performed using a LED (light emitting diode) light source and a photodiode detector. The sensor also combines pumping system, power supply, reagent and waste storage, and wireless communications into a compact and portable device. Here we report the successful use of the sensor to monitor phosphate levels in an estuarine environment.

Development and Deployment of a Microfluidic Platform for Water Quality Monitoring

There is an increasing demand for autonomous sensor devices which can provide reliable data on key water quality parameters at a higher temporal and geographical resolution than is achievable using current approaches to sampling and monitoring. Microfluidic technology, in combination with rapid and on-going developments in the area of wireless communications, has significant potential to address this demand due to a number of advantageous features which allow the development of compact, low-cost and low-powered analytical devices. Here we report on the development of a microfluidic platform for water quality monitoring. This system has been successfully applied to in-situ monitoring of phosphate in environmental and wastewater monitoring applications. We describe a number of the technical and practical issues encountered and addressed during these deployments and summarise the current status of the technology.

Autonomous analyser platforms for remote monitoring of water quality

This paper describes progress in the realization of reliable, relatively low-cost autonomous microfluidic analysers that are capable of monitoring the chemistry of water bodies for significant periods of time (weeks, months) without human intervention. The data generated is transmitted wireless to a remote web server and transferred to a web-database that renders data access location independent. Preliminary results obtained from a ‘matchbox’ scale analyzer are also presented and routes to the realization of next generation platforms discussed.

Biomimetics and materials with multiple personalities - The foundation of next generation molecular sensing devices

A strategy for advancing the price-performance capabilities of autonomous chemical sensor platforms is outlined. The importance of parallel efforts into the production of robust sensing platforms capable of autonomous monitoring of important environmental targets, while also generating potentially disruptive technologies based on fundamental materials science research is emphasised.