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Impacts of irrigation heterogeneity on sugarcane yields, energy and water use in sub-saharan Africa.
Get PDFHess, Tim M. - Associate SupervisorSugarcane is an economically strategic crop in Sub-Saharan Africa (SSA),
underpinning the rural livelihoods and economies of many SSA countries.
Despite its economic importance, yield trends in the region have been declining
by an average of 0.03 t/ha per year over the last 60 years. However, total cane
production has been increasing by an average of one million tonnes per year over
the same period – an indication that the increase in total cane production has
largely been due to an overall expansion in cultivated area. However, this
situation is not sustainable in the long-term since land availability is limited. Whilst
irrigation has the potential to improve yields, production in SSA is typically
characterised by poor irrigation management practices as evidenced by high
levels of irrigation water use, low irrigated yields and low water productivities.
Understanding the impacts of future climate variability and drought risk on the
reliability of irrigation and identifying appropriate technology and management
options to improve yields, water and energy use and productivity are key
challenges facing the agricultural sector in SSA. Impacts of irrigation non-
uniformity on cane yields, water and energy use in SSA were identified as key
research gaps in this study.
Thus, the aim of this research was to evaluate the agronomic, environmental and
economic impacts of irrigation non-uniformity on sugarcane production in SSA.
Initially, a benchmarking study was conducted to identify opportunities to improve
cane yields and water productivity and reduce irrigation water and energy use.
Biophysical crop, water balance and economic modelling approaches were then
integrated to simulate cane yield response to water, the impacts of irrigation non-
uniformity and the relative cost and benefits of improving irrigation uniformity.
Cane yields were modelled for varying water applications and irrigation uniformity
using the DSSAT Canegro model coupled with a water balance model. The
relative financial costs and benefits of implementing different interventions to
improve irrigation management were then evaluated using a spreadsheet-based
economic model.
The results showed that there were opportunities to improve the performance of
irrigated cane production in SSA – currently characterised by lower-than-
expected yields – ranging between 83.9 and 108.9 t/ha, high irrigation water uses
and lower than potential water productivity – ranging between 5.0 and 7.8 kg/m³.
It was also established that improving irrigation uniformity leads to improved cane
yields, reduced irrigation water and energy use. It was also established that on
average a percentage improvement in irrigation uniformity could improve yields
by 0.2 – 0.5 t/ha and could reduce irrigation and energy use by 3%. These
potential yield improvements (due to improved irrigation uniformity) coupled with
a reduction in water and energy use resulted in increased revenues of between
23,300 and 70,900 MK/ha (c£18 – 65/ha) and a reduction in irrigation-related
costs by 3,700 MK/ha (c £3/ha).
Overall, the research has provided new valuable insights into the impacts of
irrigation heterogeneity on cane yields and addressed existing knowledge gaps
relating to how existing irrigation management practices in the sugarcane
industry in SSA can be improved, without the need for transformational shifts to
precision irrigation technologies. The findings provide the basis for improving
cane yields, irrigation water and energy use and productivity in both commercial
and smallholder cane production across SSA.
It is, thus, recommended that there is a need for farmers to always operate
irrigation with improved level of irrigation uniformity while ensuring proper
irrigation scheduling approaches. The implementation of irrigation uniformity
improvement interventions and adopting correct irrigation scheduling methods
would likely reduce irrigation water use, improve yield average at field level which
in turn will improve water productivity and reduce energy requirements for
irrigation. The improvement of water productivity and reduction of irrigation water
use and energy requirements would maximise crop yield benefits from irrigation
and reduce irrigation operation costs, respectively.PhD in Water, including Desig
Membrane-assisted reactive crystallisation for the recovery of dissolved phosphorus in vivianite form from liquid effluents
Get PDFNovel membrane crystallisation processes resolve the mixing challenge on conventional crystallisers, by providing fixed interfacial area over which supersaturation is controlled for nucleation. Moreover, the membrane surface is thought to reduce interfacial energy and encourage micromixing. In this regard, a novel membraneassisted reactive crystallisation (MARC) process was used in this work for the dissolved phosphorous recovery in form of vivianite crystals from a phosphate-rich solution by means of the dosing of iron (II). To characterise the role of the boundary layer in controlling nucleation, a batch lab-scale system was used for the crystallization tests, and different hydraulic conditions (Reynolds ranging from 105 to 395) and polymeric membranes were tested. The crystallisation process was influenced by the hydraulic conditions, in which a low liquid velocity led to a lower induction time and vivianite supersaturation, and therefore, higher nucleation rates. Membrane properties were characterised to establish their role in the modification of the critical free energy requirement for nucleation, and for the promotion of micromixing, as possible factors that can be used to modify nucleation kinetics. As result, the bulk induction time tended to decrease with the increase in membrane hydrophobicity, roughness, pore size and porosity. Spherical vivianite nanoparticles were always synthesised with a mean size around 35 nm and a narrow distribution independently of the hydraulic conditions and membrane used. Finally, the crystallisation kinetic conformed to a diffusion-dependent nucleation mechanism, in which higher residence times for mixing increased the ion collision probability for nucleation. Importantly, this study demonstrated that MARC is an attractive prospect for nutrient recovery from wastewaters where crystal nucleation can be easily controlled by setting the operational conditions and membrane properties, eliciting considerable process intensification over existing conventional crystalliser.European Union funding: 714080Separation and Purification Technolog
Research on the dynamic response of a steel catenary riser in the touchdown zone under pigging conditions
Get PDFA periodic pigging operation performed to clean off sediment and provide operators with detailed health information for a pipeline is mandatorily required. The research on pigging-induced issues for the steel catenary riser (SCR), one of the key parts in offshore hydrocarbon recovery pipelines between the floating production system and the seabed, has been scarce until now. As a result, there is an urgent need for theories to guide the pigging operation to ensure safe pigging is achieved in deepwater risers. In this paper, a study aiming to determine the effects of the pigging impact load and the pigging-induced slugging load on the dynamic response of the riser is reported. A SCR pigging model was established and proposed based on the finite element analysis (FEA) method. The stress distribution and displacement of the SCR were investigated under the pigging conditions, with the consideration of the effects of waves, currents, and floating platform movements. It was found that the pigging load has large effects on the stress and displacement of the touchdown zone (TDZ), especially the touchdown point (TDP). The displacement of the TDZ in the Y (vertical) direction is more significant than that in the X (horizontal) direction under pigging conditions, and the maximum displacement of the TDZ in the Y direction is proportional to the weight of the pig, as well as the length of the pigging-induced slugging.Energie
Reviewing the devices of those subject to Sexual Harm Prevention Orders (SHPOs): iOS opportunities, limitations and strategies
Get PDFIn England and Wales, Management of Sexual or Violent Offenders (MOSOVO) teams are often tasked with managing offenders that are subject to Sexual Harm Prevention Orders SHPOs. These orders are put in place to protect the public and contain a series of prohibitions that allow for an offender’s conduct to be regulated and reviewed. SHPOs can be used to govern how offenders use their digital devices, particularly with regard to accessing the internet and the sending of electronic communications. To ensure SHPO compliance, officers frequently conduct reviews of any offender’s devices, sometimes manually by traversing a device’s menus and screens. These device manual reviews are not easy to conduct, often done under time pressures and in the knowledge that any missed evidence of misconduct may facilitate an offender to continue any wrongdoing and potentially increase the risk of harm to members of the public. Further, it is not always technical specialists undertaking this role. This work outlines a manual review strategy for devices running the operating system iOS (Apple products) to support officers in this role. Guided by commonly included SHPO prohibitions, relevant digital traces for evaluating SHPO compliance are highlighted, and limitations surrounding determining user behaviour are also discussed.Australian Journal of Forensic Science
Evolution of crack analysis in structures using image processing technique: a review
Get PDFStructural health monitoring (SHM) involves the control and analysis of mechanical systems to monitor the variation of geometric features of engineering structures. Damage processing is one of the issues that can be addressed by using several techniques derived from image processing. There are two types of SHM: contact-based and non-contact methods. Sensors, cameras, and accelerometers are examples of contact-based SHM, whereas photogrammetry, infrared thermography, and laser imaging are non-contact SHM techniques. In this research, our focus centres on image processing algorithms to identify the crack and analyze its properties to detect occurred damages. Based on the literature review, several preprocessing approaches were employed including image enhancement, image filtering to remove the noise and blur, and dynamic response measurement to predict the crack propagation.Electronic
Heat transfer modelling, optimisation and monitoring of flashlamp- assisted automated tape placement.
Get PDFThis study aims to develop tools for the design, optimisation and control of automated
tape placement (ATP) that integrates flashlamp heating. A thermo-optical simulation of
ATP is developed, combining a 2D finite element model of the heat conduction with 3D
ray tracing analysis. The methodology is validated against measurements acquired during
ATP trials of AS4 carbon/PEEK composites, presenting deviations up to 20°C. Flashlamp
operation at low frequency and long pulses (25 Hz /4.75 ms) results in up to 150°C higher
irradiation temperatures and increased thermal penetration depth, 100 over 50 μm,
compared to high frequency and short pulses (100 Hz/1.1 ms) or continuous operation.
Consolidation temperatures under the roller are identical for pulsing scenarios of
equivalent average power, including continuous operation. To increase computational
efficiency, an 1D simulation of ATP is put forward comprising distinct models
representing the tow, deposited material, and consolidated stack with transfer of
temperature information to ensure field continuity. The 1D solution requires only 1-2%
of the computational effort of the 2D model with a minor trade-off in accuracy, up to
14°C. Based on the efficient 1D solution, an optimisation scheme of ATP is developed
by integrating models of material degradation, interfacial bonding and a Genetic
Algorithm. The optimisation scheme identifies the Pareto front of the multi-objective
problem accurately in 25% of the computational effort required for an exhaustive search.
Strong trade-offs exist between bonding, thermal degradation and productivity, limiting
the average bonding value in the stack to 0.35 before matrix degradation exceeds the 1%
threshold typically set for aerospace applications. A monitoring strategy for ATP of
thermoplastic prepregs is proposed combining 1D analytical solutions and temperature
data acquired on the tool side of the deposited material, allowing estimation of nip point
temperatures in real time. The method integrates an inverse solution to determine the
heater power input from temperature data and enhance the nip point estimation accuracy.
The monitoring scheme presents good accuracy for a wide range of velocities, substrate
thickness and tooling materials, with an average error of 15°C even in the presence of
significant measurement noise.Engineering and Physical Sciences (EPSRC)Williams, David (Industrial Supervisor)EngD in Composites Manufactur
Identification of flexible structures dynamics.
Get PDFThe pursuit of aerodynamic efficiency and the advances in materials technology, particularly in composite material, has contributed to shifting the paradigm of
wing design to high aspect ratio wings. Increasing the span, for decreasing drag,
and using composite lightweight materials make the new wing very flexible and
prone to nonlinear dynamic behaviour. With nonlinearities, increasing challenges
arise for the identification and modelling of the wing. These challenges cannot
be overlooked for flexible structures as these models are critical for the prediction
of aeroelastic phenomena. Hence, it is fundamental to expand the knowledge
of the behaviour of these structures through the identification and modelling of
sample flexible wing models. In this work, a series of methods and approaches
are proposed and employed for the identification and modelling of a flexible wing.
First, a system identification technique in the frequency domain, the Loewner
Framework, is applied for modal parameters extraction in mechanical systems
for structural health monitoring. This new technique, with a linear reduced order
model, is used to characterise the flutter behaviour of a flexible wing. The results
are compared to similar techniques. A thorough experimental campaign is run on
a flexible wing model to characterise its nonlinear behaviour and the underlying
linear system. In particular, nonlinearities are detected, identified and quantified.
Then, a meta-model technique based on Kriging, the refined Efficient Global Optimisation, is proposed for finite element model updating. First, the technique is
used for damage detection in benchmark structures, then, it is employed for the
validation of component-based strategies for model updating of a flexible wing.Engineering and Physical Sciences (EPSRC)PhD in Aerospac
A full 3D reconstruction of rail tracks using a camera array
Get PDFThis research addresses limitations found in existing 3D track reconstruction studies, which often focus solely on specific rail sections or encounter deployment challenges with rolling stock. To address this challenge, we propose an innovative solution: a rolling-stock embedded arch camera array scanning system. The system includes a semi-circumferential focusing vision array, an arch camera holder, and a Computer Numerical Control machine to simulate track traverse. We propose an optimal configuration that balances accuracy, full rail coverage, and modelling efficiency. Sensitivity analysis demonstrates a reconstruction accuracy within 0.4 mm when compared to Lidar-generated ground truth models. Two real-world experiments validate the system's effectiveness following essential data preprocessing. This integrated technique, when combined with rail rolling stocks and robotic maintenance platforms, facilitates swift, unmanned, and highly accurate track reconstruction and surveying.Measuremen
Hydrodynamic performance of a three-unit heave wave energy converter array under different arrangement
Get PDFA pile-restrained floating wave energy converter (WEC) array is proposed as an alternative to a single floater of the size of the array for use as a floating breakwater. The hydrodynamics of the WEC are modelled based on the Navier-Stokes equations and the model is verified by comparing its results with existing experimental data. The model then is used to characterize the array composed by a line of three WECs in terms of floater heaving, wave energy conversion, wave reflection, transmission and dissipation, for different layouts.
In the examined array configuration, the aligned arrays exhibit superior performance compared to the staggered arrays, comprehensively considering both wave energy conversion and wave transmission. Specifically, when khi > 1.73, the wave energy conversion efficiency of the aligned array with a spacing of 0.1 times the WEC width ranges from 0.141 to 0.330, while the wave transmission coefficient ranges from 0.187 to 0.472, indicating the effectiveness of the arrays in simultaneously reducing wave transmission and converting wave energy under shorter-wavelength conditions. Compared to a single WEC of the same dimensions, the array exhibits a remarkable increase in wave energy conversion efficiency and effectively reduce wave reflection.Renewable Energ
Dynamic knowledge-based tracking and autonomous anomaly detection
Get PDFThis paper presents a study on the problem of region surveillance in complex terrain using an unmanned aerial vehicle (UAV), and proposes a novel framework for on-road ground target tracking and detection of anomalous driving behavior with the assistance of domain-constrained information. In order to improve the accuracy of ground target tracking, terrain information is extracted and incorporated as constraints into the tracking process. To account for the dynamic changes in terrain-constrained information, a sliding window approach leveraging a dynamic programming algorithm is employed for domain-constrained knowledge inference. To improve the autonomy and intelligence of the monitoring UAV, a mechanism for recognizing suspicious driving patterns is seamlessly integrated into the target tracking process with the aid of domain knowledge. The effectiveness of proposed method is validated using extensive numerical simulations.National Natural Science Foundation of China: Grant No. 52302449IEEE Transactions on Aerospace and Electronic System