Gerard Dooly

Low Concentration Monitoring of Exhaust Gases Using a UV-Based Optical Sensor

The development of an ultra-violet (UV) differential optical absorption spectroscopy (DOAS) fibre-optic sensor for the monitoring of vehicle exhaust gases is described in this paper. Experimental results describing the operation of this sensor with NO2, SO2 , and NO are shown. These experimental results are compared with existing published spectroscopic absorption measurements. It is shown that the minimum detectable concentration of NO2 is 1 ppm, SO 2 is 1 ppm, and NO is 26 ppm. The sensor was found to have a low susceptibility to interference between the detection of these gases

Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors

This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry–Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2–10 nmkPa and a resolution of better than ΔP = 10 Pa (0.1 cm H2O). A static pressure test in 38 cmH2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k=10.7 pmK, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes.

Precision navigation sensors facilitate full auto pilot control of Smart ROV for ocean energy applications

A Smart Remotely Operated Vehicle, ROV Latis designed as a prototype test bed for operation such as the challenging role of ocean engineering support in wave and tidal energy development is presented in this paper. With state of the art navigation sensors/instruments the vehicle can achieve precision navigation and positioning sub sea and this capability has been utilised within automatic control functionality and autopilot control systems developed and trialed on ROV Latis and not available in commercial ocean ROV technology. This paper describes the vehicles many novel design features: sensor and control systems, autopilot systems, station keeping, fully automatic way point navigation, rapid auto tuning when ROV configuration or payload is changed, fully automatic fault tolerant thruster control with redundancy. The paper also introduces the transparent ocean immersive augmented reality pilot control environment.

Optical fibre sensor for the measurement of ozone

The use of optical fibres for the measurement of ozone based on the optical absorption of both UV light at 254nm and visible light at 600nm is investigated and tested. Calculations based on the Beer-Lambert Law are also presented to demonstrate the high resolution of the UV based sensor in determining the concentration of ozone in the range of 0 mg/litre to 1mg/litre and the ability of the visible based sensor to measure high concentrations over a wide range.

Simulation and measurement of carbon dioxide exhaust emissions using an optical-fibre-based mid-infrared point sensor

A novel optical-fibre-based sensor for measurement of CO2 gas emission concentrations in exhaust systems of a motor vehicle is reported. The sensing principle is based on open-path direct absorption spectroscopy in the mid-infrared range. The sensor system comprises of low cost and compact mid-infrared components, which make it suitable for insertion into the exhaust system of automotive vehicles. The sensor utilizes a calcium fluoride CaF2 narrow band pass (NBP) filter for detection of CO2 gas without cross-sensitivity to other gases present in the exhaust system. Furthermore, it can be integrated into the mechanical and electronic interface systems of existing vehicles without any problems.

Measuring of exhaust gas emissions using absorption spectroscopy

This paper describes an optical fibre sensor for the detection of NOx (NO2 and NO) and CO2 in the exhaust system of a road vehicle. The measurement is based on a free path interaction zone which is interrogated using UV and NIR light guiding optical fibres and collimated lenses. Results are presented in the absorption spectra of the gases in the UV region for the NOx gases and NIR region for CO2. These demonstrate that using this method it is feasible to identify the individual CO2, NO and NO2 species as well as other gases in the exhaust system. Measurement of concentrations to the level of tens parts per million (ppm) have been demonstrated for the NOxx gases.

Gas detection using an integrating sphere as a multipass absorption cell

The reduction of harmful environmental pollutants which can have adverse effects on human health and the development of sensors capable of monitoring low concentrations of these pollutants is a major source of concern for many researchers today. This paper describes a multipass absorption cell used to detect and monitor the presence of several gases in the ultra violet and visible regions. An integrating sphere with a highly reflective internal coating (over 99%) was adapted in order to input and output various gases. Sulphur dioxide was detected in the ultra violet region, ozone in the visible and nitrogen dioxide in both the ultra violet and visible. This paper will report the generation of effective optical path lengths of up to 70 cm using a 5 cm diameter integrating sphere. This results in an optical sensor capable of detecting sulphur dioxide concentrations as low as 10 ppm, nitrogen dioxide concentrations as low as 4 ppm and ozone levels of the order of 500 ppm.

Secure and Efficient Key Coordination Algorithm for Line Topology Network Maintenance for Use in Maritime Wireless Sensor Networks

There has been a significant increase in the proliferation and implementation of Wireless Sensor Networks (WSNs) in different disciplines, including the monitoring of maritime environments, healthcare systems, and industrial sectors. It has now become critical to address the security issues of data communication while considering sensor node constraints. There are many proposed schemes, including the scheme being proposed in this paper, to ensure that there is a high level of security in WSNs. This paper presents a symmetric security scheme for a maritime coastal environment monitoring WSN. The scheme provides security for travelling packets via individually encrypted links between authenticated neighbors, thus avoiding a reiteration of a global rekeying process. Furthermore, this scheme proposes a dynamic update key based on a trusted node configuration, called a leader node, which works as a trusted third party. The technique has been implemented in real time on a Waspmote test bed sensor platform and the results from both field testing and indoor bench testing environments are discussed in this paper.

Detection of high level carbon dioxide emissions using a compact optical fibre based mid-infrared sensor system for applications in environmental pollution monitoring

A novel and highly compact optical fibre based sensor system for measurement of high concentrations CO2 gas emissions in modern automotive exhaust is presented. The sensor system works based on the principle of open-path direct absorption spectroscopy in the mid-infrared wavelength range. The sensor system, which comprises low cost components and is compact in design, is well suited for applications in monitoring CO2 emissions from the exhaust of automotive vehicles. The sensor system utilises calcium fluoride (CaF2) lenses and a narrow band pass (NBP) filter for detection of CO2 gas. The response of the sensor to high concentrations of CO2 gas is presented and the result is compared with that of a commercial flue gas analyser. The sensor shows response times of 5.2s and demonstrates minimal susceptibility to cross interferences of other gases present in the exhaust system.

Hazardous exhaust gas monitoring using a deep UV based differential optical absorption spectroscopy (DOAS) system

A fibre-optic sensor for the monitoring of hazardous exhaust gases is described. The sensor based on Differential Optical Absorption Spectroscopy was developed to operate within exhaust environments, monitor several exhaust gases and demonstrate low susceptibility to interferences from other gases. Experimental results describing the calibration of the sensor against a commercial analyser and tests documenting the sensors operating capabilities within the exhaust of an engine are presented. The lower limit of detection for the sensor was found to be 5ppm for nitric oxide, and 1ppm for both nitrogen dioxide and sulphur dioxide. Response times were found to be 3.4 seconds.