Colin Fitzpatrick

A review of optical fibre radiation dosimeters

Purpose – The purpose of this paper is to provide a detailed review of radiation dosimetry techniques based on optical fibre dosimeters. It presents a comprehensive bibliography of the current research activities in the area.Design/methodology/approach – A range of published work on optical fibre radiation dosimeters are presented, with the merits and limitations discussed. Each radiation dosimetry technique is discussed in turn, providing examples of dosimeters using such techniques reviewed. The main focus is on gamma radiation although other radiation dosimeters are considered.Findings – This paper provides information on the wide range of research activity into radiation dosimeters. The dose ranges of these dosimeters are presented, along with the advantages and disadvantages of different dosimetry techniques.Originality/value – A comprehensive review of published research in the area of solid radiation dosimetry is presented in this paper. It provides an individual with a review of the various techni...

CO2 monitoring and detection using an integrating sphere as a multipass absorption cell

This paper describes a multipass absorption sensor based on an integrating sphere. The sphere has an internal coating which is highly reflective (over 95%) in the near infrared region and this allows for the detection of CO2 at two regions in the spectrum: 2 µm and 1.57 µm. CO2 was detected around the 2 µm region using a light emitting diode as the emitter and a photodiode as the detector, while detection at the 1.57 µm region took place using a broadband ASE source as the emitter and a miniature spectrometer as a detector. A 2 in diameter (50.8 mm) integrating sphere was used as an absorption gas cell. This paper reports the generation of effective optical path lengths of 114 cm at the 1.57 µm region and 40 cm at the 2 µm region. Experimental results demonstrating the detection of CO2 using a 2 in diameter integrating sphere are presented and simulation results based on larger integrating spheres are also reported. Further simulations conducted in the mid-infrared region suggest the possibility of detecting trace levels of CO2 (less than 200 ppm) using a 2 in diameter integrating sphere.

Real-time gamma dosimetry using PMMA optical fibres for applications in the sterilization industry

The use of polymethylmethacrylate (PMMA)-based plastic optical fibre as an intrinsic real-time gamma dosimeter is investigated. The radiation-induced attenuation of the fibres is monitored in situ during the course of irradiation. The PMMA fibre exhibited a linear radiation- induced attenuation response at various wavelengths for a dose range of 50 Gy to 50 kGy. The sensitivity, ranging from 0.4 dBm−1 kGy−1 to 0.03 dBm−1 kGy−1, is wavelength dependent, with high sensitivity at the lower wavelengths.

Increased penetration of wind generated electricity using real time pricing & demand side management

Ireland aims to source 40% of its electricity needs from renewable energies by 2025, 86% of which will supplied by Wind power. Harnessing the power of Irelands large indigenous wind resource will make the security of electricity supply more resilient against fluctuations in international energy markets. In order for customers and suppliers to fully exploit the potential benefits offered by large amounts of wind power it will be necessary to offer dynamic pricing tariffs such as Time-of-Use tariffs and Real-Time-Pricing to the domestic market. These time based tariffs are becoming increasing feasible as Ireland embarks on the nationwide roll-out of Smart Metering. In conjunction with the aforementioned tariffs, smart metering could allow customers to self-regulate their electricity usage behaviour in a more favourable manner that ultimately promotes the increased penetration of wind generated electricity. The following analysis looks at the potential of these tariffs as our generation portfolio moves from 11% to 40% renewable energy supply.

A novel multi-point ultraviolet optical fibre sensor based on cladding luminescence

A novel multi-point optical fibre sensor for ultraviolet detection is presented. The sensor is a single piece of large-core polymer optical fibre which has had sections of its cladding stripped and replaced with phosphor-doped epoxies. These photoluminescent coatings act as the new cladding. Two points on the fibre have been coated with a different phosphor, each providing a different emission spectrum (red and green) when stimulated by ultraviolet radiation. The spectral emission intensity is dependent on the strength of the incident ultraviolet radiation. Part of this emission is coupled to the fibres core through the evanescent wave of guided modes within the core. The fibres output is monitored using a low-cost miniature spectrometer. The spectrometer output is used to interpret the different phosphor emission spectra and thus determine localized axial locations on the fibre of increased or decreased ultraviolet intensity. Results are included in the form of spectra (400–900 nm) under different ultraviolet stimulation conditions. An expanded version of this sensor has applications in monitoring ultraviolet water and waste-water sterilization units.

Evaluating the sustainability potential of a white goods refurbishment program

A sustainable national policy on waste electronic and electrical equipment reuse has to ensure an integrated environmental economic and social approach. In this paper, a quantitative model is developed that permits a comparative analysis of re-use and non-re-use scenarios from an environmental and economic perspective. The model demonstrates the importance of considering user consumption profiles and the changing national electricity generation portfolio in determining the best end-of-life strategy, whether it should be reuse or recycling. A case study of Ireland is used to demonstrate the model. From a social perspective, qualitative aspects of reuse, such as the job creation potential and the impact on prosperity for low income families, are also considered. Reuse of white goods, if conducted through social enterprises, will create more employment than an equivalent amount of recycling for those most vulnerable to unemployment. Any environmental and social dividends from re-use can be realized only in the context of an economically sustainable system. This would include such factors as a secure supply of suitable equipment, a competitive cost base and sufficient revenues from sales and other sources in order for the business to survive. In an attempt to examine whether a white goods re-use program could possibly operate in a competitive manner with new appliances, this study has examined examples of comparable businesses operating in the EU as well as interpreting data on consumer demand.

Feasibility of Using Radio Frequency Identification to Facilitate Individual Producer Responsibility for Waste Electrical and Electronic Equipment

Regulatory measures that hold producers accountable for their products at end of life are increasingly common. Some of these measures aim at generating incentives for producers to design products that will be easier and cheaper to recover at the postconsumer stage. However, the allocation of recovery costs to individual producers, which can facilitate realization of the goals of these policies, is hindered by the practical barrier of identification and/or sorting of the products in the waste stream. Technologies such as radio frequency identification (RFID) can be used for brand or model recognition in order to overcome this obstacle. This article assesses the read rate of RFID technology (i.e., the number of successful retrievals of RFID tag data [“reads”] in a given sample of tagged products) and the potential role of RFID tags in the management of waste electrical and electronic equipment (WEEE) at current levels of technical development. We present the results of RFID trials conducted at a civic amenity site in the city of Limerick, Ireland. The experiment was performed for fixed distances up to 2 meters on different material substrates. In the case of white goods (i.e., large household appliances), a 100% read rate was achieved using an RFID handheld reader. High read rates were also achieved for mixed WEEE. For a handheld scan of a steel cage containing mixed WEEE, read rates varied from 50% to 73% depending on the ultrahigh frequency (UHF) metal mount tag employed and the relative positioning of the tags within the cage. These results confirm that from a technical standpoint, RFID can achieve much greater brand or model identification than has been considered feasible up to now, and thus has a role to play in creating a system that allocates recovery costs to individual producers.

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

Monitoring of carbon dioxide exhaust emissions using mid-infrared spectroscopy

An optical fibre sensor for monitoring carbon dioxide emissions from modern road vehicles and operating in the mid-infrared spectral region is reported. The wavelength range of operation is centred at 4.23??m and has required a novel implementation of this sensor using low cost and robust components. The sensor is shown to be capable of detecting CO2 to a minimum level of 350?ppm, to be stable over several hours of continuous operation and insensitive to the presence of other species present in the exhaust.

Promotion of wind generated electricity using price responsive Demand Side Management: Price prediction analysis for imperfect energy storage

Ireland aims to source 40% of its electricity needs from renewable energies by 2020. This will be largely met by intermittent energy sources, primarily such as wind, wave and solar. Given an inherent lack of flexibility of these energy sources it is necessary to explore methods of increasing the flexibility of demand rather than supply. Price based Demand Side Management that reflects pricing in a spot price electricity market offers an incentivised method by which this can be achieved. This analysis investigates the implications of using day-ahead pricing predictions to demand side manage a load with an inherent energy loss due to rescheduling.