Biocontrol of ochratoxigenic fungi by endogenous lactic acid bacteria and yeasts from ivorian robusta coffee in the context of climate change

Verheecke-Vaessen, Carol - Associate Supervisor Fontana, Angelique - Associate Supervisor Strub, Caroline - Associate SupervisorThis doctoral research delves into the innovative domain of biocontrol strategies targeting mycotoxigenic fungi in the context of climate change. Focusing on Ivorian coffee, a vital economic and agricultural commodity, the study explores the potential of indigenous lactic acid bacteria (LAB) and yeasts as biocontrol agents. Mycotoxins, toxic secondary metabolites produced by fungi, pose significant health risks and economic losses. As climate change amplifies the proliferation of mycotoxigenic fungi, the demand for sustainable and eco-friendly interventions intensifies. The research encompasses comprehensive isolation, identification, and characterization of LAB and yeasts from Ivorian coffee, evaluating their antagonistic properties against mycotoxigenic fungi. Furthermore, the study elucidates the mechanisms underlying the biocontrol activity, shedding light on how these microorganisms mitigate mycotoxin contamination. This research is pivotal in the pursuit of climate-resilient strategies for mycotoxin management, contributing to both food safety and agricultural sustainability.PhD in Environment and Agrifoo

Social life cycle assessment: a systematic review from the engineering perspective

Social Life Cycle Assessment (SLCA) has emerged as a crucial element in sustainability discussions, gaining traction in academic research and industry practices. In response to increasing consumer awareness, governmental regulations, and corporate responsibility, sustainable production models have been widely adopted, influencing engineering projects to address not only environmental but also social impacts. This systematic review aims to explore the application of SLCA within the engineering field, focusing on key trends, methodologies, and challenges engineers face when implementing SLCA. To achieve this purpose, 196 peer-reviewed studies published between 2010 and 2024 were analysed through bibliometric and content analysis. The results reveal an increasing trend in SLCA research, with key contributions from energy, mechanical engineering, and chemical engineering fields. Despite its growing relevance, several methodological challenges persist, including a lack of standardisation, data availability issues, and difficulties in integrating SLCA with environmental and economic assessments. The findings of this research can facilitate academic researchers, industrial managers, and policymakers in implementing SLCA practices in engineering applications for a comprehensive sustainability assessment.This work was funded through Innovate UK program grant agreement with grant number [103040]International Journal of Sustainable Engineerin

AI-driven 5G networks for autonomous positioning system platform

Unmanned Aerial Vehicles (UAVs) are becoming essential for various urban applications, such as surveillance, delivery, logistics, disaster management, and traffic monitoring. However, their positioning performance in urban environments can be limited due to challenges such as non-line-of-sight (NLOS) propagation, multipath interference, and signal blockage caused by tall buildings, trees, and other obstacles. These factors lead to reduced positioning accuracy and unreliable communication. To address these issues, this thesis introduces three key and novel contributions. First, it presents one of the first real-world evaluations of the 5G network performance for UAV operations at altitudes between 50 and 110 meters, using XCAL-based field trials. This provides new insights into the altitude-dependent Quality of Service (QoS) parameters such as latency, throughput, and handover (HO) efficiency and provides practical recommendations for UAV-specific connectivity protocols. Second, a novel hybrid positioning framework is proposed that integrates the observed time difference of arrival (OTDOA) of the new 5G radio (NR) with the fusion of sensor and barometric pressure sensor through an Extended Kalman Filter (EK). This combination significantly improves positioning accuracy (2.8–7 m) in GNSS GNSS-challenged urban environment, which has not been demonstrated in prior UAV studies. Third, the thesis introduces a lightweight feedforward neural network (FNN) for mitigating NLOS errors in 5G-based UAV positioning. Trained on simulated MATLAB data, the model corrects time-of-arrival (TOA) measurements in real time, reducing positioning error to 1.3 m in LOS and 1.7 m in NLOS, outperforming conventional methods. Unlike existing solutions, this model is designed for real-time deployment on UAV platforms with limited resources. Overall, this research strengthens UAV navigation and connectivity in urban airspace by combining 5G advancements, sensor fusion, and AI-powered error correction. The novelty lies in the integration of real-world 5G performance analysis, a hybrid OTDOA sensor fusion framework, and an AI-based NLOS correction model into a unified solution for reliable, accurate, and scalable Urban Air Mobility (UAM), opening the door to future improvements in AI-driven 5G networks for autonomous system platforms.PhD in Aerospac

Top management involvement in key account management: a contingency model

Prior, Daniel - Associate SupervisorKey Account Management (KAM) plays a strategic role in driving long-term customer value, yet its implementation remains challenging. While prior research recognises the importance of Top Management Involvement (TMI) in KAM, limited attention has been paid to what drives such involvement, how it manifests in practice, and how it is shaped by contextual contingencies. This study addresses these gaps through an abductive, multi-case research design involving seven organisations. It identifies 19 drivers of TMI, categorised along proactive–reactive and strategic–operational–individual dimensions. TMI is found to manifest across three behavioural domains: displayed commitment, decision- making approach, and interaction style. Importantly, the study demonstrates that structural, environmental, cognitive, and operational contingency factors moderate the relationship between TMI drivers and executive behaviours. These findings make theoretical contributions by refining and extending the conceptualisation of TMI, increasing our understanding of how personal traits influence TMI, illustrating its dynamic nature, and challenging the assumption that TMI is inherently beneficial to KAM performance. The study also offers practical insights for aligning executive involvement with KAM demands. It presents a set of ten role templates for executive involvement in KAM and concludes with limitations and suggestions for future research.PhD in Leadership and Managemen

Body force modelling for axial and centrifugal compressor pre and post-stall aerodynamics

Tunstall, Richard - Industrial Supervisor Mazur, Steven - Industrial Supervisor Harvell, John - Industrial SupervisorThe operation of a jet engine is limited in a way to ensure that the manifestation, propagation and growth of local flow compressor instabilities is prevented. This inevitably leads to more conservative compressor designs with increased surge margins and reduced operating range to avoid the occurrence of unstable compressor phenomena. These instabilities are known as rotating stall and surge and their implications on the structural integrity and operability of the engine can be catastrophic. These phenomena and the inception mechanisms that trigger their occurrence are not yet fully understood, while the knowledge gap is exacerbated when considering centrifugal or axi-centrifugal configurations. The cost of experimental campaigns for the investigation of the post-stall response of aero-engine compression systems is excessive, while the compressor is usually restricted to low rotational speeds to prevent severe structural damage. The experiments can only be performed at a more advanced, mature phase of the compressor design process. Sophisticated transient simulations using commercial CFD software offer an alternative approach but the excessive associated computational cost requirements make their real-life usage challenging. Through-flow codes combining reduced and higher-order modelling methods are a computationally efficient alternative, however very few validated implementations are reported in the literature and their capabilities are strictly limited to axial compressor configurations. A lower-order modelling approach is developed, whereby the compression system is solved as an empty duct with body force-fields imparting turning and losses to the flow. A new body force model, applicable to all types of blades is developed. The blade curvature is fully defined in three dimensions accounting for axial, circumferential, radial forces and blade leaning. The flow-field solution is obtained transiently by solving the 2D axisymmetric Euler equations on a body force-relevant grid which ensures that the grid lines are aligned with bladed domains. The governing equations with blockage in the relative frame of reference are derived, thus replicating both metal and aerodynamic blockage effects, along with a method for the precise definition of the additional blockage terms in convoluted ducts. The Godunov scheme coupled with 3 Riemann solvers is used to obtain the fluxes. New analytical, simplified models are derived to estimate aerodynamic blockage and mixing losses at reverse flow conditions in impeller and axial blade passages. Loss correlations are used to estimate losses at forward flow conditions, while mixed and reverse flow are treated with a separate model. The validity and limitations of the different modelling approaches are investigated extensively using test-case scenarios and CFD data. The validation of the overall through-flow framework is carried out on axial compressor and centrifugal compressor stages using CFD and if available, experimental data. Steady-state, forward and reverse flow characteristics are in good agreement with CFD and experimental data, while the flow-field is reproduced with reasonable accuracy. Transient, post-stall simulations in centrifugal compressors are carried out and validated against experimental data. The code constitutes the first successful, validated, through-flow approach, capable of predicting the post-stall, steady-state and transient aerodynamic performance in centrifugal compressors.PhD in Aerospac

Evaluation of the impact of coagulant choice on phosphorus removal from municipal wastewater

Jefferson, Bruce - Associate SupervisorPhosphorus removal is a critical objective in municipal wastewater treatment due to its role in eutrophication and the tightening of regulatory discharge limits. Chemical coagulation remains the most widely adopted method for phosphorus control; however, its effectiveness is influenced by coagulant type, pH conditions, dosing location, and wastewater matrix composition. This thesis aimed to advance the understanding of how these operational and chemical variables govern the mechanisms of phosphorus removal, with the goal of optimising coagulant selection and application strategies under real-world conditions. A comprehensive screening of 17 coagulants, including ferric, aluminium, rare earth, zinc, and calcium-based formulations, was conducted under both uncontrolled and pH-adjusted conditions. Ferric sulphate, polyaluminium chloride (PACL), and aluminium sulphate emerged as the most effective agents, achieving residual total phosphorus concentrations as low as 0.35 mg/L, 0.15 mg/L and 0.6 mg/L, respectively, under controlled pH conditions, particularly under neutral pH, where stable hydroxide flocs are favoured. Rare earth coagulants demonstrated high phosphate affinity but formed fragile flocs, limiting their practical application. Floc characterisation revealed that compact, shear-resistant aggregates correlated strongly with higher removal efficiency. To investigate the role of pH, a detailed comparative analysis of ferric sulphate (FS), aluminium sulphate (ALS), and PACL was performed across a pH range of 4-8. The results confirmed that coagulant solubility, hydrolysis potential, and metal speciation significantly impact phosphorus removal efficiency. FS and ALS were better than PACL under acidic conditions due to more complete hydrolysis and formation of stable flocs. Phosphorus fractionation and turbidity data supported these trends, identifying pH 6-7 as the optimal window for coagulant performance and floc settleability. The final phase of the study examined how dosing location in the crude influent, after primary settling tanks (PST), and in the final effluent (FE) influences coagulant performance. FS showed enhanced phosphorus removal even in high-strength crude wastewater, though required careful pH control to avoid over-acidification. ALS and PACL were more effective at PST and FE, where organic loading and particulate interference were lower. A two-point dosing strategy applied to crude wastewater was found to enhance phosphorus removal while reducing total coagulant demand, offering a practical route for chemical cost optimisation. Collectively, this thesis delivers critical insights into the physicochemical and operational factors driving chemical phosphorus removal. The findings inform coagulant selection and deployment in diverse wastewater environments, support compliance with future phosphorus discharge standards, and contribute to the development of cost-effective and environmentally sustainable treatment strategies.PhD in Wate

Underwater skimming improves retention and degradation of Cryptosporidium oocysts in slow sand filters

Cryptosporidium oocysts are resilient protozoan pathogens that resist conventional disinfection, posing significant challenges to drinking water quality. Filtration processes like slow sand filters (SSFs) effectively remove these oocysts, but limited data exist on their fate in SSFs, particularly following maintenance practices such as skimming. This study examined the spatial and temporal distribution of inactivated Cryptosporidium parvum oocysts in pilot-scale SSF operated under two skimming regimes: dry skimming and underwater skimming. The underwater skim approach offers benefits in terms of production volume gains and reduced downtime, but pathogen removal has not been comprehensively assessed using this approach. Across two 4-day dosing periods, oocyst breakthrough was lower under UWS (UWS: 7.6 % vs DS: 47.0 % of filtrate samples were positive for oocysts). In addition, core samples were collected at six time points to track oocyst retention and vertical migration. In both underwater skim and dry skim slow sand filters, most oocysts were captured in the top 100 mm of the filter, gradually moving downward over time. Notably, underwater skim filters retained more oocysts in the upper layers than dry skim filters, resulting in lower breakthrough frequency. Although skimming did remove some oocysts in both regimes, the majority were rendered undetectable in situ through processes such as predation, enzymatic digestion, and natural decay—evidenced by the increasing proportion of oocyst-like bodies and their near-complete absence from the filtrate. Thus, underwater skim is a viable alternative to dry skim for Cryptosporidium removal, sustaining filter performance by trapping oocysts in the upper layers and maintaining similar rates of oocyst degradation. These insights support improved SSF maintenance strategies that enhance pathogen removal.The authors acknowledge the financial support of the Engineering and Physical Sciences Research Council (EPSRC), through PhD award to Sophie Bretagne (EP/T518104/1), and support from Thames Water.Cleaner Engineering and Technolog

Immersed boundary method with improved implicit direct-forcing for fluid–structure interaction problems

An improved implicit direct-forcing immersed boundary method (DF-IBM) is proposed for simulating interactions between incompressible fluid flows and complex rigid structures undergoing arbitrary free motion, commonly referred to as fluid–rigid body interaction problems. The proposed approach harnesses the pressure implicit with splitting of operators (PISO) algorithm to efficiently handle the dual constraints of the fluid–solid system in a segregated manner. Consequently, the divergence-free condition is maintained throughout the Eulerian domain, while the kinematic no-slip velocity boundary condition is exactly enforced on the immersed boundary, also termed as the fluid–structure interface. A new pressure Poisson equation (PPE) is derived, incorporating the boundary force directly where the no-slip condition is satisfied. This approach avoids altering the coefficient matrix of the PPE, which could otherwise introduce convergence issues, enabling the use of fast iterative PPE solvers without modifications. The improvement involves integrating Lagrangian weight methods, having better reciprocity over the IBM-related linear operators, within the implicit formulation. An additional force initialization scheme is introduced to accelerate the convergence of the no-slip boundary condition, thereby improving the algorithm’s performance. The Navier-Stokes equations are coupled with the rigid body dynamics, described by the Newton-Euler equations, within the improved DF-IBM framework. Both explicit and implicit coupling algorithms are developed to address weakly and strongly coupled fluid–rigid body interaction problems, respectively, under a partitioned approach. Stability and convergence issues, particularly stemming from critical solid–fluid density ratios and/or the rigid body approximation of the internal mass effects (IME) in rotational dynamics, are mitigated using a fixed relaxation technique for the rigid body kinematics. For implicit coupling, a fixed-point strategy is employed, complemented by the relaxation technique used for the IME to ensure robustness. Additionally, the proposed coupling algorithms leverage the DF-IBM formulation and the predictor-corrector strategy of the PISO solution algorithm, by excluding the momentum predictor step and the time-intensive corrector loops from the implicit iterations. The proposed method is validated through various stationary, prescribed, and freely moving immersed boundary cases, with results compared against experimental and numerical data from the literature. The method demonstrates robustness, accuracy, and efficiency in handling the complex dynamics of fluid–rigid body interactions across a range of challenging scenarios. The suggested improvements integrate seamlessly into existing incompressible fluid solvers with minimal adjustments to the original system of equations, highlighting their ease of implementation. Finally, the present work is implemented within the cell-centred finite volume approach inside the open-source C++ toolbox OpenFOAM environment, version 7.0 of the OpenFOAM Foundation variant.PhD in Energy and Powe

Nutrient dynamics and recovery efficiencies in a decentralised faecal sludge and food waste treatment system

Decentralised faecal sludge (FS) and food waste (FW) treatment systems like co-composting system offer more practical solutions for waste treatment and nutrient recovery in low- and middle-income countries, yet nutrient recovery and losses across this system remain poorly quantified.This study aimed to assess the flows, losses, and recovery efficiencies of nitrogen (N), phosphorus (P) & potassium (K) with the goal of recommending measures to minimize pollution to water bodies. Raw FS, FW, compost, and effluent samples were collected at each treatment stage over three treatment cycles from August 2021 – 2022 in Somanya, Ghana. A total of 108 composite samples were collected and analysed for N,P & K using standard procedures. The N, P & K losses at each stage of the treatment system were calculated using the mass balance principle and the nutrient flow diagrams were created using the Sankey diagram generator. Results show that, 59-86% N, 8-40% P and 49-81% K were lost at the dewatering stages for all cycles. Losses were lumped together as either gaseous losses, adsorption to media surfaces or percolate. The overall nutrient recovery efficiency of the system was 6–17% N, 20–37% P & 17-24% K in co-compost and treated effluent. Despite high removal efficiencies in the facultative ponds, the final effluent did not meet EU standards. Effluent may become a resource in geographies that have scarce water and less stringent regulations. This study recommends strategies and approaches such as biochar use, percolate/leachate recirculation and covering of compost piles to reduce nutrient losses.We would like to acknowledge the Sue White Fund, Cranfield University and the International Water Management Institute for funding this work.Environmental Technology & Innovatio

Architecting ATA 28 with model-based systems engineering: center of gravity balance and system performance

The fuel management system for a fixed-wing aircraft has been developed and explored with the model-based systems engineering (MBSE) methodology for maintaining the center of gravity (CoG) and analyzing flight safety. The system incorporates high-level modeling abstractions that exploit a mix of behaviors and physical detail resembling real-world components. This approach enables analysis for a multitude of system requirements, verification, and failure scenarios at high simulation speed, which is necessary during system definition. Initially, the CoG is maintained by directly accessing the flight deck valves and pumps in both wings and controlling them through the bang-bang control law. In the refinement phase of the fuel system controller, the manual and individual controls of the valves and pumps are replaced with an autonomous fuel transfer scheme. The autonomous scheme achieves no more than a 20 kg difference in fuel between the wings during normal conditions. In the event of failures, the controller achieves no more than a 100 kg difference in fuel between the wings. The difference returns to 20 kg within a settling time of 5 sec and a maximum allowable overshoot safety margin of 10% of the 20 kg difference in normal conditions (±2 kg). The specification 20 kg/5 sec band varies with pump and valve parameters. Although this specification is sufficient for a system-level model, it can be refined with pump and valve parameters and nonlinear effects in the network. The system identification method is also trialed to control an individual engine by estimating a proportional integrator derivative (PID) controller of the engine plant. The safety tests are initiated in a user interface enabling error detection and injection. The fuel system model is used for analyzing refueling, defueling, and jettison scenarios with appropriate flow rates. Besides the CoG maintenance, several aspects of configurations of the system’s functional and logical architecture, considering increasing component redundancy and activities for MBSE framework, have been conducted. The logical and temporal verification of system requirements is performed in simulation. To ensure traceability and coverage, the requirements and the associated verification artifacts are digitally linked to the implementing blocks. Test scenarios are implemented for investigating resultant and emergent behaviors at various levels of system hierarchy by isolating either the subsystem or the components that have been performed. To further check out the MBSE workflow, the fuel system controller code has been directly emitted from the controller model for DO-178C objectives. At the mission-level validation, a jettison scenario is developed for a mission and flight plan in the digital mission engineering and systems analysis environment of Systems Tool Kit (STK) Aviator. The aircraft fuel system configuration is set using the fuel system model. The power of MBSE methodology supported by a modeling and simulation framework provides plenty of opportunities for through-life analysis in the early design lifecycle phase.SAE International Journal of Aerospac