A Probabilistic Environmental Decision Support Framework for Managing Risk and Resources

The ability to make cost effective, timely decisions associated with waste management and environmental remediation problems has been the subject of considerable debate in recent years. On one hand, environmental decision makers do not have unlimited resources that they can apply to come to resolution on outstanding and uncertain technical issues. On the other hand, because of the possible impending consequences associated with these types of systems, avoiding making a decision is usually not an alternative either. Therefore, a structured, quantitative process is necessary that will facilitate technically defensible decision making in light of both uncertainty and resource constraints. An environmental decision support framework has been developed to provide a logical structure that defines a cost-effective, traceable, and defensible path to closure on decision regarding compliance and resource allocation. The methodology has been applied effectively to waste disposal problems and is being adapted and implemented in subsurface environmental remediation problems

The application of a long period grating sensors to human respiratory plethysmography

A series of nine in-line curvature sensors on a garment are used to monitor the thoracic and abdominal movements of a human during respiration for application to Human Respiratory Plethysmography. These results are used to obtain volumetric tidal changes of the human torso which show agreement with data from a spirometer used simultaneously to recorded the inspired and expired volume at the mouth during both rhythmic and transient breathing patterns. The curvature sensors are based upon long period gratings which are written in a progressive three layered fibre to render them insensitive to refractive index changes. The sensor consists of the long period grating laid upon a carbon fibre ribbon, with this then encapsulated in a low temperature curing silicone rubber. The sensing array is multiplexed and interrogated using a derivative spectroscopy based technique to monitor the response of the LPGs' attenuation bands to curvature. The versatility of this scheme is demonstrated by applying the same garment and sensors to various human body types and sizes. It was also found from statistical analysis of the sensing array data, in conjunction with the measurements taken with a spirometer, that 11 to 12 sensors should be required to obtain an absolute volumetric error of 5%

The bending and temperature characteristics of long period gratings written in elliptical core step-index fibre

We describe the characterisation of long period gratings written in elliptical core fibre, which yield a discriminatory sensor for curvature and temperature with a resolution ±0.05m-1 for curvature and ±0.9 °C for temperature

Embedded progressive-three-layered fiber long-period gratings for respiratory monitoring

A long-period grating (LPG) was written into a progressive three-layered single-mode fiber that was embedded into a flexible platform as a curvature sensor. The spectral location and profile of the LPGs were unaltered after implantation in the platform. The curvature sensitivity was 3.747 nm m with a resolution of ± 1.1 × 10-2 m-1. The bend sensor is intended to be part of a respiratory monitoring system and was tested on a resuscitation training manikin. © 2003 society of Photo-Optical Instrumentation Engineers

A high sensitivity refractometer based upon a long period grating Mach-Zehnder interferometer

A low cost interrogation scheme is demonstrated for a refractometer based on an in-line fiber long period grating (LPG) Mach–Zehnder interferometer. Using this interrogation scheme the minimum detectable change in refractive index of ?n ~ 1.8×10-6 is obtained, which is the highest resolution achieved using a fiber LPG device, and is comparable to precision techniques used in the industry including high performance liquid chromatography and ultraviolet spectroscopy

An ultra-sensitive localised surface plasmon resonance fibre device for environmental sensing based upon a structured bi-metal coating

We demonstrate a bi-metal coating (platinum and gold or silver) localised surface plasmon resonance fibre device that produces an index spectral sensitivity of over 11,000 nm/RIU, yielding an index resolution of 5×10-6in the aqueous index regime, consisting of a structured multi-layered thin film on D-shaped fibre. © 2014 SPIE

An optical fiber Bragg grating tactile sensor

Tactile sensors are needed for many emerging robotic and telepresence applications such as keyhole surgery and robot operation in unstructured environments. We have proposed and demonstrated a tactile sensor consisting of a fibre Bragg grating embedded in a polymer "finger". When the sensor is placed in contact with a surface and translated tangentially across it measurements on the changes in the reflectivity spectrum of the grating provide a measurement of the spatial distribution of forces perpendicular to the surface and thus, through the elasticity of the polymer material, to the surface roughness. Using a sensor fabricated from a Poly Siloxane polymer (Methyl Vinyl Silicone rubber) spherical cap 50 mm in diameter, 6 mm deep with an embedded 10 mm long Bragg grating we have characterised the first and second moment of the grating spectral response when scanned across triangular and semicircular periodic structures both with a modulation depth of 1 mm and a period of 2 mm. The results clearly distinguish the periodicity of the surface structure and the differences between the two different surface profiles. For the triangular structure a central wavelength modulation of 4 pm is observed and includes a fourth harmonic component, the spectral width is modulated by 25 pm. Although crude in comparison to human senses these results clearly shown the potential of such a sensor for tactile imaging and we expect that with further development in optimising both the grating and polymer "finger" properties a much increased sensitivity and spatial resolution is achievable

Cardiac induced localised motion of the human torso detected by a long period grating fibre optic sensing scheme

Cardiovascular health of the human population is a major concern for medical clinicians, with cardiovascular diseases responsible for 48% of all deaths worldwide, according to the World Health Organisation. Therefore the development of new practicable and economical diagnostic tools to scrutinise the cardiovascular health of humans is a major driver for clinicians. We offer a new technique to obtain seismocardiographic signals covering both ballistocardiography (below 20Hz) and audible heart sounds (20Hz upwards). The detection scheme is based upon an array of curvature/displacement sensors using fibre optic long period gratings interrogated using a variation of the derivative spectroscopy interrogation technique. © 2014 SPIE

Fiber optic sensing of magnetic fields utilizing femtosecond laser sculpted microslots and long period gratings coated with Terfenol-D

Fiber optic sensors are fabricated for detecting static magnetic fields. The sensors consist of a UV inscribed long period grating with two 50 micron long microslots. The microslots are fabricated using the femtosecond laser based inscribe and etch technique. The microslots and the fiber surface are coated with a magnetostrictive material Terfenol-D. A spectral sensitivity of 1.15 pm/mT was measured in transmission with a working resolution of ±0.2 mT for a static magnetic field strength below 10 mT. These devices also present a different response when the spatial orientation of the fiber was adjusted relative to the magnetic field lines

Characterization of infrared surface plasmon resonances generated from a fiber-optical sensor utilizing tilted Bragg gratings

We demonstrate the use of tilted fiber gratings to assist with the generation of infrared surface plasmons on a metal film coating the flat of a D-shaped fiber. The wavelength of the strong (>25 dB) resonance is tunable over similar to 1000 nm by adjusting the polarization state of the light and is highly sensitive to the refractive index of any aqueous medium surrounding the fiber (sensitivity= 3365 nm)