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An investigation of combined biaxial tensile and shear deformations in textile woven fabrics
Get PDFTextile fabrics undergo complex deformation during processing, wear and use.
Determining how a fabric behaves is important for understanding its performance. While
traditional testing methods focus on evaluating a fabric’s mechanical properties, usually
along one axis, this study considers the measurement of combined forces which is more
realistic under real life conditions. A new apparatus has been constructed named IrisTex
inspired by the iris movement of the human eye, capable of applying and measuring
combined tensile and shear forces simultaneously in biaxial and uniaxial formats. The
current study focuses on the application of low stresses, as typically found in fabrics used
for garment making, and hence aims the use of the machine to establish the deformation
behaviour during processing and wear.
The apparatus is equipped with 4 load cells of 111N maximum capacity to measure
low tensile and shear forces. Deformations of 2°, 4° and 8° are applied at 0,24 °/sec by
four stepper motors at speeds up to 50 mm/sec and 250 N thrust. The apparatus is
specially constructed for low noise, where friction in the bearings is only 1% of the forced
applied, and hence it is capable of measuring forces as low as 0,1 N/cm and producing
complete force-recovery curves representing combined bi-shear and bi-tensile behaviour
from which mechanical values can be obtained. The interface of the apparatus to the
computer is done using LabVIEW and the testing procedure allows for changing of the
testing conditions and datalogging.
Initially, one cotton fabric was tested to set the testing protocols, examine limitations
and to analyse and understand the combined tensile and shear curves. Once completed,
four more commercially available fabrics were tested and analysed. Meaningful
hysteresis curves for combined tensile and shear have been produced for all tested fabrics.
The curves were interpreted and characterised to enable fabric to fabric comparison. For
the combined tensile curve, properties such as Initial Combined Tensile Modulus (TMint)
and Maximum Force (Fmax) were calculated. While for the combined shear curves,
values such as Transverse Maximum Force (Fsmax) and Combined Shear Rigidity
between 0,5° and 4° (Gc), that represent the ease with which the yarns bend and rotate
inside the fabric under the combined deformation were also measured and reported. The
results of the combined mechanical properties were meaningful in terms of measuring the
combined tensile and shear properties of the fabrics
Development of front-end pre-analytical modules for integrated blood plasma separation
Get PDFBlood plasma separation is a fundamental step in numerous biomedical assays involving
low abundance plasma-borne biomarkers. The interest in microscale blood plasma
separation solutions has emerged with the development of microfluidic technologies in
the early 2000s and has continued in recent years as few solutions have so far achieved
both high yield and high purity without sample dilution, in volumes compatible with
current clinical assays. Hydrodynamic or acoustic blood plasma separation microdevices
have attracted considerable attention from the microfluidic community in the continuous
separation of blood samples with a volume of a few mL due to their high throughput and
insensitivity to clogging. However, obtaining a high yield from whole blood is
challenging because the volume of red blood cells or hematocrit typically rises above
physiological levels after each separation region, following plasma extraction. Some key
parameters that influence the microfluidic blood plasma separation efficiency and yield
of such devices have been investigated in this project. In particular, this project sought to
establish experimentally, for the first time, the maximum hematocrit level and flow rate
achievable in a microchannel, without hemolysis. Furthermore, the influence of flow
fluctuation in syringe pumps, which are commonly employed in microfluidic setups, on
the separation performance of blood plasma separation devices was investigated. These
studies not only reveal the reasons behind the slow progress in the development of high-throughput microfluidic blood plasma separation devices capable of handling whole
blood samples but also provides a framework for the design optimisation of future
microfluidic blood plasma separation devices. While for low to mid-volume clinical
sample volume (<4 mL), microscale solutions are viable, for high clinical sample
volume (>4 mL) blood plasma separation traditional centrifugation approach remains the
gold standard but is currently cost-prohibitive. In the third part of this thesis, a low-cost
and open-source centrifugation setup for clinical blood sample volume has been
developed. This centrifugation system capable of processing clinical blood tubes could
be valuable to mobile laboratories or low-resource settings where centrifugation is
required immediately after blood withdrawal for further testing
Theoretical and experimental investigation of pore confinement effects in gas condensate reservoirs
Get PDFUnconventional resources play an important role to meet future energy demands. Recent
advances in technology has made the production from unconventional reservoirs feasible.
However, it is necessary to properly study the phase behavior and flow of fluids within
these reservoirs as they are not well understood.
In this thesis, the impacts of fluid confinement effects, which refers to the impact the
small pore spaces and pore walls on the fluid phase behaviour due to non-negligible
interactions between pore walls and fluid molecules, on the phase behaviour of gas
condensate systems within real unconventional rocks, were investigated. A novel
experimental procedure was designed to measure dew point pressure (Pdew) of various
gas-condensate fluid mixtures within different real shale rocks. Several experiments were
performed to realistically study the impacts of gas condensate fluid composition,
temperature, net stress and rock type on the extent of the pore confinement effects. The
trends for the impacts of confinement Pdew of single component fluids and gas
condensate mixtures were analyzed and it was observed that pore confinement would
increase the Pdew of gas condensate mixtures while reduced the Pdew of single
component fluids. The impacts of the presence of heavier components in the gas
condensate mixture was found to be significant. In line with the experimental
measurements, the equation of state describing confined fluid phase behavior of gas
condensate mixtures was modified by modifications in binary interaction parameters. A
new correlation based on the Lennard Jones interaction potential was presented to take
into account the interactions between fluid and wall molecules. The proposed correlation
was tuned based on the experimental results. The error of the predictability of the
correlations for core sample and the fluids not used in its development was found to be
within an acceptable range.
Based on the modified equation of state obtained, numerical simulations were performed
to investigate the impacts of pore confinement on the performance of the unconventional
reservoirs. It was noted that gas production was slightly higher using the confined fluid
mode which was mainly attributed to the lower fluid viscosity due to confinement. When
pressure drawdown (DP) was low, models with bulk fluid produced more condensate.
However, when DP increased, models with confined fluid produced more. Considering
dual porosity model, dual porosity-dual permeability model, adsorption, and diffusion did
not alter these trends
Linear and nonlinear wave equation models with power law attenuation
Get PDFMotivated by the need to model high intensity focused ultrasound in lossy media
we study linear and nonlinear wave equations that contain non local time fractional
derivatives, whose inclusion in our models incorporates the effects of acoustic attenuation. This is characterized by a frequency dependent power law parametrized
by a non integer γ ∈ (0, 2), leading to the need for fractional derivative damping.
Issues with such integro-differential equations arise in the continuous and discrete
analysis due to singularities that occur at t = 0 and as a result of their non local
nature. To address these issues we present results that carefully show how to treat
such equations for smooth and non smooth solutions, and we derive fast and efficient
numerical schemes that pay particular attention to the handling of these non local
operators.
As well as acoustic attenuation the models we consider will need to account for
nonlinear propagation effects that result from the focusing of the ultrasound waves
and be modelled on an unbounded domain. To combat this issue, we use a perfectly
matched layer. That is, we truncate the unbounded domain to a finite computational
domain and impose an absorbing, non reflecting boundary layer around it.Engineering and Physical Sciences Research Council (grant EP/L016508/01
On the development and enhancement of artificial intelligence algorithms for swarm robots in real world applications
Get PDFSwarm robotics is an area where using artificial intelligence (AI) can show a great deal of
improvement. Obstacle avoidance, object detection, mapping and navigation are some
the major algorithms required for successful execution of various tasks in the field of
robotics. There is a challenge in applying these algorithms in a manner that swarm
robots can use effectively. These five areas can be further researched to provide a
platform for real world applications. This research aims to tackle the challenges involved
in applying the aforementioned algorithms to swarm robotics and comparing the results
with single robot systems. These techniques can be optimized by leveraging the
advantage of swarm robots communication and scalability. The proposed algorithms
were tested and validated using swarm robots along with profiling and simulations. For
obstacle avoidance, two algorithms were devoloped. The first used a novel and modified
force field method and the second used artificial neural networks (ANN). The results
showed that the modified force field method performed better for static environments
while ANNs worked better for dynamic environments. For object detection, the proposed
algorithm uses an image classifier developed using ANN. The image classifier was
trained to identify blocks of various colours using a convolutional neural network
technique. This algorithm was then applied to swarm robotics using two proposed
methods and results showed that multiple robots viewing objects from different angles
provided better results as compared to single robot systems. This was validated with a
97% accuracy. In two dimension (2D) mapping, the proposed algorithm was developed
using simultaneous localization and mapping (SLAM). The results showed that a single
robot can require upto 3.5x more time for covering a given area compared to a swarm
size of ten robots. This research shows a great deal of contribution in applying swarm
robotics for surveilance purposes by showcasing the ability for swarm robotics to
coordinate and execute the required task in an efficient time frame. The proposed
three-dimension (3D) mapping algorithm used octomaps and occupancy grids to map out
an image taken from a camera mounted on swarm robots. The images were obtained
from various angles using multiple swarm robots. AI algorithms with a focus on swarm
robotics are developed and enhanced for real world applications including fire-fighting,
surveillance, fault analysis and construction. Results showed that swarm robots were
able to complete a given task by up to six times faster as compared to a single robot. The
overall contribution of this research lays a platform for further applications by
showcasing the effectiveness of robotic algorithms in a swarm robot environment.Heriot-Watt University Fee Scholarshi
Integrating geological uncertainty and dynamic data into modelling procedures for fractured reservoirs
Get PDFModelling, simulating and characterising flow through naturally fractured reservoirs is
a multi-disciplinary effort. The scarcity of data combined with the additional layer of
complexity that fractures add to a reservoir makes an efficient integration of all available data fundamental. However, the vast range of data types to be considered and the
multitude of disciplines giving their input often results in communication barriers and
individuals working within their comfort area, creating further challenges for uncertainty
propagation. It is however critical for decision-making to develop geologically consistent
reservoir models that recognise the challenges of simulating flow through systems with
high permeability and scale contrasts and address the need for an ensemble of reservoir
models to sufficiently cover geological uncertainties and their impact on fluid flow.
In this work I developed several workflows for naturally fractured reservoir modelling
that invite cross-disciplinary thinking by integrating geological uncertainties and dynamic
data into the modelling procedure and foster ensemble modelling from the start. The
workflows are tested on a synthetic field that is based upon a conceptual model for
fold-related fracture distributions. The first workflow involves the use of multiple-point
statistics to efficiently model reservoir-scale fracture distribution by upscaling discrete
fracture networks and converting them into training images. To cover the impact of
fracture-related geological uncertainties on fluid flow efficiently, flow diagnostics were
used to screen and afterwards cluster and select training images according to their flow
response for further reservoir modelling. The second workflow proposes a novel reservoir
modelling technique that considers both static and dynamic data and utilises entropy to
generate a diverse ensemble of reservoir models that all match an outset objective. Finally,
an agent-based reservoir modelling workflow is introduced, where within a reservoir
model, independent but interacting agents follow a set of rules to generate reservoir
models that take into account geological prior information and expected dynamic flow
responses to drive modelling efforts.
Overall, we demonstrated that combining approaches from various disciplines into cross-disciplinary workflows provides great potential for subsurface characterisation. What
workflow to adopt within a project, depends on various boundary conditions. The availability of data and time, the confidence in the understanding of the reservoir and the
ultimate goal behind the modelling exercise. These factors can impact whether moving
along with the simpler, more parametric multiple-point statistics workflow, the entropy-driven workflow that utilises static and dynamic data or the more data-driven agent-based
modelling workflow is the right choice.James Watt Scholarshi
Quantum networking with optimised parametric down-conversion sources
Get PDFQuantum information processing exploits superposition and entanglement to enable
tasks in computation, communication and sensing that are classically inconceivable.
Photonics is a leading platform for quantum information processing owing to the
relative ease in which the encoding and manipulation of quantum information can be
achieved, but there are a set of characteristics that photons themselves must exhibit
in order to be useful. The ideal photon source for building up multi-qubit states
needs to produce indistinguishable photons with high efficiency. Indistinguishability
is crucial for minimising errors in two-photon interference, central to building larger
states, while high heralding rates will be needed to overcome unfavourable loss
scaling. Domain engineering in parametric down-conversion sources negates the
need for lossy spectral filtering allowing one to satisfy these conditions inherently
within the source design.
Contained in this Thesis are two experimental investigations. Within the first
investigation, we present a telecom-wavelength parametric down-conversion photon
source that operates on the achievable limit of domain engineering. The source is
capable of generating photons from independent sources which achieve two-photon
interference visibilities of up to 98.6 ± 1.1% without narrow-band filtering. As
a consequence, we can reach net heralding efficiencies of 67.5%, corresponding to
collection efficiencies exceeding 90%. These sources enable us to efficiently generate
multi-photon graph states, constituting the second experimental investigation.
Graph states, and their underlying formalism, have been shown to be a valuable
resource in quantum information processing. The generation and distribution of a
6-photon graph state—defining the topology of a quantum network—allows us to
explore prospective issues with networks that invoke protocols beyond end-to-end
primitives, where users only require local operations and projective measurements.
In the case where multiple users wish to establish a common key for conference
communication, our proof-of-principle experiment concludes that employing N-user
key distribution methods over 2-user methods, results in a 2.13 ± 0.06 key rate
advantage
Understanding viscous instability and capillary retention in porous media with relevance to polymer flooding
Get PDFThe economic viability and producibility challenges associated with recovering viscous oils have been surmounted by new technologies and modifications of methods
developed for conventional oils. This is also true downstream, where advances in science and technology have reduced the refining expenses for viscous oils. Moreover,
about 40% of the total world oil reserves are viscous or extra-viscous. These incentives encourage oil companies to invest in viscous oil reservoirs, joining companies
that have produced viscous oil for decades. Nevertheless, they inevitability need to
adapt for the world conscious effort towards environmental stability. Though most
produced viscous oils so far have come from thermal processes, several cases do exist
where thermal methods are neither technically feasible nor economically profitable.
In such cases, non-thermal methods have to be applied.
Any non-thermal displacement method of viscous or extra-viscous oil will cause
instability that will directly impact the sweep efficiency. Being widely used for conventional oil reservoirs, polymer has recently been screened for viscous oil reservoirs
and shown promising results in displacement stability and recovery efficiency. As
a result, abundant reviews were devoted to the instability and ways of reducing it,
but the subject still lacks understanding. In particular, we are interested in the
parameterisation of the instability and the effect of the end-point mobility ratio and
the phase mobility functions on the observed instability based on the proposed parameter. Also, recent experimental and numerical observations show that polymer
flooding stabilises instability compared to waterflooding. So, another interest to us
is how the proposed parameter can explain such observation. Capillary retention
is another flow phenomenon that makes the sweep efficiency even more adverse in
viscous oil. At the lamination or bedding scale and with the presence of the capillary force, fluid flow through a porous medium with abrupt changes in heterogeneity
causes phase retention. The tendency of these laminae or beds to lead to a cumulative oil retention effect at high viscosity ratios needs explanation. In particular,
what controls this retention and how polymer changes the retention regime under
unsteady state displacement are some of major inquiries that we have dealt with in
this work.
In the study, a methodical approach was conducted, starting from the first principles that describe the two-phase flow in porous media. Various analytical methods were deployed for given assumptions to analyse the governing flow equations and
derive analytical results. These results were demonstrated and verified by solving
the flow equations numerically. For the instability problem and based on the generalised Saffman-Taylor criterion, a new dimensionless parameter is proposed that
correlates with the observed instability. For a porous medium at connate water,
the instability parameter is a function of the shock speed and shock total mobility.
Although derived for a homogeneous medium, the instability parameter can also be
used for a heterogeneous medium. Due to the similarity in the formulations describing the displacement between water and polymer, i.e. both admit shock fronts, the
instability parameter is extended to polymer flooding. The correlation between the
instability parameter and the observed instability is validated numerically on a 2D
heterogeneous medium for different sets of phase mobility functions for waterfloods
and polymer floods. The stabilisation effect of polymer flooding is explained in light
of the instability parameter and the fractional flow analysis. Baside the numerical
validation, the instability parameter is validated experimentally using coreflood experiments with various oil viscosities. For six corefloods, The breakthrough time
and the instability parameter show a good correlation.
For capillary retention, The steady state retention theory has important implications for unsteady state retention. At the steady state, the concept of stationarity
strip explains the oil retention for the whole range of fractional flow values at the
capillary-viscous regime. This result follows that oil retention will materialise during unsteady state displacement. The peak size and the time it occurs are best
understood based on the so-called local flow parameter, which is a function of the
reciprocal capillary number, capillary variable, the viscous limit fractional flow and
the end-point mobility ratio. Analysis shows that as the end-point mobility ratio is
reduced, the local flow parameter increases, which indicates that the flow regime is
shifted towards the viscous limit. This shift results in a decrease in the peak size
and the time at which it occurs. These results were validated numerically using
one-dimensional unsteady state displacements of waterfloods and polymer floods.
Polymer flooding has demonstrated the capability of reducing the size of the peak
retention and bringing it towards lower injection time. Experimental results demonstrate a good consistency with the retention theory. In particular, the measured
uneven saturation jumps at the heterogeneity interface predicted by the stationarity
strip concept are evident
Study, design and development of carbon quantum dots-based graphic carbon nitride (g-C₃N₄) nanocomposites in photocatalysis for dye wastewater treatment
Get PDFThe issues of global water scarcity and climate change due to industrial pollution have
been thrusted to the forefront of world attention in the recent years. Photocatalytic
technology is widely regarded as a green and sustainable strategy in addressing
environmental and energy-related challenges due to the utilization of virtually
inexhaustible solar energy. One of the main obstacles of existing photocatalytic system
include low photoresponse towards visible light which leads to mediocre photocatalytic
efficiencies. Furthermore, the rapid recombination of electron-hole pairs shortens the life
span of charge carriers that are instrumental to the redox reactions that occur on the
surface of the photocatalyst. The exploitation of two-dimensional (2D) graphitc carbon
nitride (g-C3N4) has opened up new possibilities and promising opportunities to the field
of photocatalysis. Herein, the construction of homojunction-based photocatalysts and
introduction of carbon quantum dots (CQD) have been proposed to enhance the
photocatalytic performance of g-C3N4 semiconductor. The hybridization of zero-dimensional (0D) CQD and 2D g-C3N4 induces synergistic effects owing to its excellent
electrical conductivity, high electron mobility and aqueous solubility. The CQD-incorporated g-C3N4 nanocomposites are endowed with various mechanisms of
photocatalytic enhancement which include extended spectral sensitivity and effective
separation of charge carriers. In the present work, highly efficient CQD-based g-C3N4
photocatalysts were developed for photodegradation of RhB dye. As an auxiliary study,
one of the experimental phases has been extended to include CO2 photoreduction to
further validate the photoactivity assessment. The photoreactions were performed under
irradiation of visible light to imitate the process of natural photosynthesis which takes
place in plants. Several modifications were conducted to further boost the photocatalytic
performance of CQD/g-C3N4 nanocomposites by introducing heteroatoms such as boron,
sulfur and phosphorus. Upon identifying the optimum photocatalyst sample, a plausible
photocatalytic RhB degradation mechanism was proposed followed by the study of
process optimization. To promote the robustness of the as-developed photocatalyst
sample, the homojunction-based g-C3N4 was integrated into a 3D-printed photoreactor
via thermoset coating in the assembly of a comprehensive photocatalytic system. In
overall, the CQD-based g-C3N4 photocatalytic nanocomposite is anticipated to be
developed as a robust solution in combating global challenges from the perspectives of
environmental and energy sustainability
Improved oil recovery by miscible/near miscible CO2 gas injection : experimental and simulation approaches
Get PDFMiscible gas flooding has recently overtaken to be the most successful enhanced oil
recovery technique. Carbon dioxide flooding is an integral part of miscible gas flooding.
This thesis focuses on the feasibility of the implementation of miscible CO2 flooding and
demonstrates the effects of different parameters, alongside alternative approaches to EOR
which my result in more incremental oil production.
To distinguish the miscibility of CO2 gas and oil, a key parameter of miscible CO2
flooding is the determination of the minimum miscibility pressure (MMP). MMP is the
minimum pressure at which the oil and injected gas achieve miscibility so that previously
trapped oil can be recovered. MMP can be determined in a variety of ways: through
experimental, analytical, and computational methods, as well as through other empirical
relationships. In common industry practice to define MMP, a series of carefully designed
slim tube tests is required. However, since slim tube testing is time-consuming and costly,
mathematical correlations are attractive, as they require few input parameters and little
information regarding the fluids and are quick and easy to use. This thesis develops a
more accurate MMP correlation for pure CO2 injection into high temperature reservoirs
by applying a series of 17 new MMP slim tube experiments, with the assistance of a large
database of slim tube MMPs that has been published in the literature.
Gas/oil interfacial tension (IFT) is seen as one of the most critical fluid characteristic
properties in oil reservoirs affecting gas injection production. Because IFT does not
appear in the flow equations directly, it would be difficult for the current commercial
reservoir simulator to capture its effect. Very few experimental data are available in the
literature on displacement involving a low IFT. However, those data were based on
synthetic oil not crude oil. This study evaluated the performance of miscible/near miscible
gases as a displacing fluid. The study investigated the feasibility of near-miscible CO2
application and improve our understanding of the mechanisms of near-miscible CO2
flooding by conducting a series of two-phase CO2 gas/oil core flood experiments under
reservoir condition in a carbonate core. Phase behaviour studies were carried out to
characterize the near miscible conditions. Slim tube and swelling/extraction tests were
performed to identify the near miscible range and eliminate mass transfer mechanisms to
create phase equilibrium for the displaced fluid/fluid flow in porous media. The study's overall results indicate that near miscible could achieve the same ultimate oil
recovery as miscible condition. This outcome will define a new strategy when applying
CO2 gas injection hence economical in terms of compression costs.
Reliable relative permeability curves of oil/gas systems are important for the successful
simulation and modelling of gas injections, especially when the miscibility condition
approaches. In this study, a series of relative permeability were obtained by history match
the experiential data at different IFT level (immiscible, intermediate, and near miscible).
To investigate the IFT scaling effect on gas/oil relative permeability. The results shows
that the relative permeability of both gas and oil increase as the IFT decreases, but not
equally. As the system moves from immiscible toward miscible conditions, the relative
permeability increases, and its curvature reduces but does not achieve straight crossline.
Finally in This thesis, will demonstrate the two different approaches in modeling miscible
gas injection utilizing compositional and extended black oil model. Fully compositional
model is complex and required a lot of information. Extended black oil simulation is an
alternative approach to compositional simulation and provides an engineering tool to
account for oil displacement by a miscible or immiscible fluid. the result shows that using
EOS to obtain for MCM Miscible CO2 indicate that excellent prediction to experimental
data at 1-D simulation. However, utilizing the ultra-low relative permeability for
predicting the miscible displacement has shown promising results in terms of the ultimate
oil recovery, this new approach would allow the performance of miscible displacement
to by predicted utilizing the black oil model
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