Investigation of ethanol and methanol water mixtures in the visible wavelength area using fibre-optic evanescent field absorption sensors based on a u-shaped, a coil-shaped and a meander-shaped probe
2008 IEEE Sensors Applications Symposium
An optical fibre evanescent field sensor for methanol (CH3OH) and ethanol (C2H5OH) solvents based... more An optical fibre evanescent field sensor for methanol (CH3OH) and ethanol (C2H5OH) solvents based on deformed optical fibre cores is reported. The sensitivity of an existing U-bend probe is increased by extending the exposed core to a coil shape of one and a half turns and by forming the core to a meander- shape with three bends. Using the visible wavelength area (VIS) and methanol/ethanol concentrations from 0% to 10% it is shown that the sensitivity of the meander shape sensor enables the determination of methanol concentrations of better than 0.5% and of ethanol concentrations of better than 0.2% at 650 nm. This facilitates the use of low cost optical sources and receivers provided for this wavelength range as well as the utilization of polymer optical fibres to guide the light to and from the sensor which results in low cost applications compared to all silica or polymer clad silica fibre solutions in the near-infrared (NIR) or ultra-violet (UV) wavelength range.
2017 Eleventh International Conference on Sensing Technology (ICST), 2017
The Internet of Things (IoT) has presented many new dimensions to information technology and data... more The Internet of Things (IoT) has presented many new dimensions to information technology and data communications and has helped to develop the concepts of Smart City, Smart Travel, Smart Surveillance, Smart Health, Smart Energy, Smart Agriculture, etc. IoT offers lots of opportunity to alter conventional monitoring methods through the use of Smart IT, but it has performance limitations in terms of computational resources, limited storage and processing big data. By merging IoT and cloud computing the industry can overcome the low processing power and storage limitations of IoT, since, cloud computing is ubiquitous, comprises high computational and storage capacity ability, has unlimited virtual resources available and is capable of processing big data. However, the cloud is not a free resource and its costs need to be managed. In this paper, we discuss various cost issues which need to be smartly managed for Industries adopting the Cloud with IoT.
International Journal on Smart Sensing and Intelligent Systems, 2020
The system presented in this paper demonstrates how a novel fibre optic based sensing platform, c... more The system presented in this paper demonstrates how a novel fibre optic based sensing platform, capable of detecting minute changes in the level of impurity in a liquid, can be incorporated onto a Mote based platform enabling real time monitoring of a body of water. How these features can be used to detect a representative sample of chlorophyll within a aquatic environment, will be demonstrated. Systems currently deployed worldwide include satellite mapping technology and high cost water monitoring platforms. Growing international emphasis on the management of water quality is giving rise to an expansion of the international market for novel robust, miniaturized, intelligent water monitoring systems capable of measuring local environmentally detrimental events such as localised small scale chemical pollution.
International Journal of Internet Protocol Technology, 2018
The IPSec is used to secure the IP traffic. The IPSec protocol was designed to fulfil the need to... more The IPSec is used to secure the IP traffic. The IPSec protocol was designed to fulfil the need to provide security at the network level, so that all the higher-layer protocols in the OSI model could take advantage of it. The implementation of IPSec is a computationally heavy task that affects the high speed network performance. To overcome this issue, the best possible solution is hardware implementation. For a hardware implementation the FPGA platform is considered as one of the best solutions because of its re-configurability and high performance capabilities. The work presented here gives a complete FPGA based implementation of IPSec. This includes both (AH and ESP) IPSec protocol formats. Both IPSec formats are implemented using transport mode and tunnel mode operations. IPSec is not bounded to use any specific cryptographic algorithms; here IPSec is used with the AES and SHA-3 algorithms to provide confidentiality and integrity services respectively.
A miniature sensor for accurate measurement of pressure (depth) with temperature compensation in ... more A miniature sensor for accurate measurement of pressure (depth) with temperature compensation in the ocean environment is described. The sensor is based on an optical fibre Extrinsic Fabry-Perot interferometer (EFPI) combined with a Fibre Bragg Grating (FBG). The EFPI provides pressure measurements while the Fibre Bragg Grating (FBG) provides temperature measurements. The sensor is mechanically robust, corrosion-resistant and suitable for use in underwater applications. The combined pressure and temperature sensor system was mounted on-board a mini remotely operated underwater vehicle (ROV) in order to monitor the pressure changes at various depths. The reflected optical spectrum from the sensor was monitored online and a pressure or temperature change caused a corresponding observable shift in the received optical spectrum. The sensor exhibited excellent stability when measured over a 2 h period underwater and its performance is compared with a commercially available reference sensor also mounted on the ROV. The measurements illustrates that the EFPI/FBG sensor is more accurate for depth measurements (depth of ~0.020 m).
Oceanic conditions play an important role in determining the effects of climate change and these ... more Oceanic conditions play an important role in determining the effects of climate change and these effects can be monitored through the changes in the physical properties of sea water. In fact, Oceanographers use various probes for measuring the properties within the water column. CTDs (Conductivity, Temperature and Depth) provide profiles of physical and chemical parameters of the water column. A CTD device consists of Conductivity (C), Temperature (T) and Depth (D) probes to monitor the water column changes with respect to relative depth. An optical fibre-based point sensor used as a combined pressure (depth) and temperature sensor and the sensor system are described. Measurements accruing from underwater trials of a miniature sensor for pressure (depth) and temperature in the ocean and in fresh water are reported. The sensor exhibits excellent stability and its performance is shown to be comparable with the Sea-Bird Scientific commercial sensor: SBE9Plus.
A comprehensive study of the effect of a wide range of controlled human subject motion on Photopl... more A comprehensive study of the effect of a wide range of controlled human subject motion on Photoplethysmographic signals is reported. The investigation includes testing of two separate groups of 5 and 18 subjects who were asked to undertake set exercises whilst simultaneously monitoring a wide range of physiological parameters including Breathing Rate, Heart Rate and Localised Blood Pressure using commercial clinical sensing systems. The unique finger mounted PPG probe equipped with miniature three axis accelerometers for undertaking this investigation was a purpose built in-house version which is designed to facilitate reproducible application to a wide range of human subjects and the study of motion. The subjects were required to undertake several motion based exercises including standing, sitting and lying down and transitions between these states. They were also required to undertake set arm movements including arm-swinging and wrist rotation. A comprehensive set of experimental results corresponding to all motion inducing exercises have been recorded and analysed including the baseline (BL) value (DC component) and the amplitude of the oscillation of the PPG. All physiological parameters were also recorded as a simultaneous time varying waveform. The effects of the motion and specifically the localised Blood Pressure (BP) have been studied and related to possible influences of the Autonomic Nervous System (ANS) and hemodynamic pressure variations. It is envisaged that a comprehensive study of the effect of motion and the localised pressure fluctuations will provide valuable information for the future minimisation of motion artefact effect on the PPG signals of this probe and allow the accurate assessment of total haemoglobin concentration which is the primary function of the probe.
Recent advancements in cloud computing technologies in the context of optical and optical fibre b... more Recent advancements in cloud computing technologies in the context of optical and optical fibre based systems are reported. The proliferation of real time and multi-channel based sensor systems represents significant growth in data volume. This coupled with a growing need for security presents many challenges and presents a huge opportunity for an evolutionary step in the widespread application of these sensing technologies. A tiered infrastructural system approach is adopted that is designed to facilitate the delivery of Optical Fibre-based "SENsing as a Service-SENaaS". Within this infrastructure, novel optical sensing platforms, deployed within different environments, are interfaced with a Cloud-based backbone infrastructure which facilitates the secure collection, storage and analysis of real-time data. Feedback systems, which harness this data to affect a change within the monitored location/environment/condition, are also discussed. The cloud based system presented here can also be used with chemical and physical sensors that require real-time data analysis, processing and feedback.
International Journal of Distributed Sensor Networks, 2014
IEEE 802.15.4 is the technology behind wireless sensor networks (WSNs) and ZigBee. Most of the IE... more IEEE 802.15.4 is the technology behind wireless sensor networks (WSNs) and ZigBee. Most of the IEEE 802.15.4 radios operate in the crowded 2.4 GHz frequency band, which is used by many technologies. Since IEEE 802.15.4 is a low power technology, the avoidance of interference is vital to conserve energy and to extend the lifetime of devices. A lightweight classification algorithm is presented to detect the common external sources of interference in the 2.4 GHz frequency band, namely, IEEE 802.11-based wireless local area networks (WLANs), Bluetooth, and microwave ovens. This lightweight algorithm uses the energy detection (ED) feature (the feature behind received signal strength indication (RSSI)) of an IEEE 802.15.4-compliant radio. Therefore, it classifies the interferers without demodulation of their signals. As it relies on time patterns instead of spectral features, the algorithm has no need to change the channel. Thus, it allows the radio both to stay connected to the channel a...
Power management in operating systems for wireless sensor nodes
Proceedings of the 2007 IEEE Sensors Applications Symposium, SAS, 2007
Technological advancements in recent years have enabled the development of tiny, cheap, disposabl... more Technological advancements in recent years have enabled the development of tiny, cheap, disposable, and self contained battery powered computers, known as sensor nodes or "motes", that can accept input from an attached sensor, process this input and transmit the results wirelessly to some interested device(s). When a number of these nodes work together, conceivably up to hundreds of thousands, a
Investigation of binary liquid aqueous methanol and ethanol mixtures using meander-shaped fibre-optic evanescent-wave absorption sensors
Proceedings of IEEE Sensors, 2008
A fibre-optic evanescent-wave field absorption sensor based on a meander-shaped sensing probe is ... more A fibre-optic evanescent-wave field absorption sensor based on a meander-shaped sensing probe is described. The influences of the fibre core diameter and the refractive index of the surrounding medium on the sensitivity are evaluated by using binary liquid mixtures, in particular methanol and ethanol solved in distilled water at concentrations from 0 to 10 volume percent (%vol). The resolution was experimentally proved to be about 5ldr10-5 refractive index units at a wavelength of 650 nm, which corresponds to a resolution of about 0.2%vol methanol and 0.1%vol ethanol concentration. The LED based design as well as the chosen wavelength (POF suitable) result in a low cost sensing application. Finally, an analytical approach for predicting the refractices indices of liquid mixtures (Lorentz-Lorenz equation) was examined for validity with regards to the mentioned aqueous methanol/ethanol solutions.
Analysis of hardware encryption versus software encryption on wireless sensor network motes
Lecture Notes in Electrical Engineering, 2008
... Analysis of Hardware Encryption Versus Software Encryption on WSN Motes 11 Table 2Comparison ... more ... Analysis of Hardware Encryption Versus Software Encryption on WSN Motes 11 Table 2Comparison of implemented block ciphers Block size Key size No. ... This is the case because, as can be seen in Table 2, a 64 bit key is used for RC5 and a 80 bit key is used for Skipjack ...
SAS 2009 - IEEE Sensors Applications Symposium Proceedings, 2009
... A node replication attack is particularly serious when the base station is cloned ... Overall... more ... A node replication attack is particularly serious when the base station is cloned ... Overall there are more successful attacks against Bluetooth security than the other security suites ... TinySec TinySec [9] is a link layer security architecture for wireless sensor networks, implemented for ...
Fibre-optic evanescent-wave field fluid concentration sensor
2009 6th International Multi-Conference on Systems, Signals and Devices, SSD 2009, 2009
ABSTRACT A fibre-optic fluid concentration sensor based on refractive index measurements is repor... more ABSTRACT A fibre-optic fluid concentration sensor based on refractive index measurements is reported. Its working principle is validated for some simple aqueous primary alcohol mixtures, such as Acetone, Ethanol, Methanol, 1-Propanol, and 2-Pro-panol, covering a concentration range from 0% vol to 10% vol. With a simple and low cost LED based measurement setup a resolution of about 0.00005 refractive index units was achie-ved, which approximately corresponds to 0.2% methanol, 0.75% ethanol and acetone, and 0.05% 1-propanol and 2-propanol. Moreover, described sensing method is applicable for all fluids that show different refractive indices at different concentrations, which by far is the case for almost all fluids, since the refractive index of a mixture is related to its density.
Development of a prototyping platform for the integration of multiple fiber optic sensing devices to a SHIMMER™ system for in-situ maritime monitoring
Proceedings of IEEE Sensors, 2009
The new SHIMMER prototyping platform has been augmented to allow for use as an environmental wire... more The new SHIMMER prototyping platform has been augmented to allow for use as an environmental wireless sensing device. To date the Shimmer has been primarily used by the health industry. However, the prototype presented in this paper has been designed to allow for the integration of multiple sensing platforms, so that the Shimmer platform can be used for the monitoring
Large-core fibre-cavity design for ring-down experiments
2010 IEEE Sensors Applications Symposium, SAS 2010 - Proceedings, 2010
A fibre-cavity design based on highly reflective gold coatings, vapor-deposited to the two end fa... more A fibre-cavity design based on highly reflective gold coatings, vapor-deposited to the two end faces of a large core multimode waveguide, is presented. In contrast to common fibre-cavity approaches, the laser pulses are not coupled through the reflective coatings into the cavity but through a micro hole in one of the fibre end faces, which reduces the commonly very high coupling loss to less than 1%. Accordingly, lower demands on the source power and the sensitivity of the receiver circuit result in lower costs of ring-down sensor approaches. An estimate of the ringdown time constant of the fibre-cavity is given and the influence of the micro-hole on the reflection loss is discussed.
A novel and scalable key management scheme for wireless sensor networks
2010 IEEE Sensors Applications Symposium, SAS 2010 - Proceedings, 2010
Due to the sensitive nature of the data gathered by many wireless sensor networks (WSNs) it is be... more Due to the sensitive nature of the data gathered by many wireless sensor networks (WSNs) it is becoming critical that this data be protected. However, due to the constrained nature of the resources available on sensor nodes, traditional wireless networking security solutions are not viable because of their processing and memory requirements, power consumption, speed and communications overhead. In particular,
Uploads
Papers by Elfed Lewis