20505 research outputs found
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Application of energy and exergy balances to drag decomposition in unsteady incompressible flows
No full textThe accurate evaluation of aerodynamic drag in unsteady flows presents an ongoing challenge for aerodynamic optimisation in tightly coupled engine-airframe configurations. This thesis investigates the use of energy and exergy balance formulations as alternative approaches for drag evaluation, with a focus on their ability to decompose drag power into recoverable and irreversible contributions. Three two-dimensional laminar flow test cases were examined using CFD simulations in ANSYS Fluent. The first, a stationary cylinder at Re = 140 undergoing vortex shedding, served as a benchmark and confirmed that both balances reproduce near-field drag values with high accuracy while revealing the conversion of mechanical energy into viscous dissipation along the wake. The second case, involving an oscillating cylinder in static fluid, demonstrated that the balances remain applicable even in the absence of net aerodynamic drag force, capturing the redistribution of energy through viscous effects in agreement with analytical predictions. The third case combined vortex shedding with azimuthal wall oscillation, producing a more complex flow where the balances showed a modest increase in mean drag but no fundamental changes to dissipation mechanisms. Together, these results establish the robustness of energy and exergy balances for unsteady drag evaluation and highlight their potential for usage in optimisation of aerodynamic performance.MSc in Aerospace Computational Engineerin
Decision factors of air cargo freight forwarders for transport service providers in different geographic regions: a systematic literature review
No full textAir cargo transportation facilitates companies in global supply chains in organising production on different continents. High value and perishable goods make extensive use of air cargo as preferred mode of transport. Shippers typically outsource their transportation needs to freight forwarding companies with extensive expertise and global presence. The air cargo industry remains relatively underexplored academically and little is known about the decision making of freight forwarding companies in selecting air transport service providers such as airlines, airports and trucking companies. While existing research investigates Asian exports, there is lack of research from the past 25 years on the distinct European market context. This paper aims to review the literature that is available in the field of decision making at air cargo freight forwarding companies and synthesises the outcomes. The paper also identifies that there is no literature available on freight forwarding companies selecting trucking companies that provide pick-up services at the shipper as part of the air transport chain. Finally, continuation of research is proposed in the field of decision making at European based freight forwarding companies exporting air cargo shipments from Europe.TRPRO_14th International Conference on Air Transport – INAIR 2025: Fly High, Learn FarTransportation Research Procedi
Environmental and economic comparison of wire and swarf in a novel additive manufacturing technique for aerospace applications
No full textIn the context of sustainable manufacturingSustainable manufacturing, the choice of materials and processes significantly impacts the environmental footprint and overall costs of additive manufacturingAdditive manufacturing (AM). This study investigates the use of wire versus swarfSwarf feedstock as feedstocks in a novel additive manufacturingAdditive manufacturing technique process and compares these methods with Wire Arc Additive ManufacturingAdditive manufacturing (WAAM). Specifically, the carbonCarbon footprint (CO2 emissions), energyEnergy consumption, and cost implications of each approach are evaluated. The findings reveal that, while wire-based methods are commonly employed for their precision and quality, swarf recycled from manufacturing waste offers substantial environmental benefits by reducing energyEnergy consumption and lowering carbonCarbon emissions. Moreover, the cost comparison shows that swarf can reduce overall production costs, providing a more cost-effective solution, especially in high-volume aerospace applications. This work highlights the potential of integrating swarf into WAAM processes as a sustainable alternative, offering insights into optimizing both environmental performance and economic viability in AM. The results are expected to contribute to the advancement of more sustainable and economically viable additive manufacturingAdditive manufacturing strategies.The authors acknowledge funding from the UK EPSRC project Sustainable Additive Manufacturing EP/W01906X/1.Energy Technology 2026The Minerals, Metals & Materials Serie
Analysis of the risk of climate hazards to the airport system
No full textClimate hazards are increasingly disrupting the normal functioning of airports worldwide,
leading to damage, operational disruptions, safety concerns, economic loss and broader
business, environmental and social impacts. Climate extremes such as storms,
precipitation, and heat waves are increasing in occurrence and magnitude. As the Earth
warms, these threats are only set to grow, placing additional stress on airport infrastructure
and current operating practices. While airports make efforts to mitigate risks, a critical gap
remains in understanding the scale and complexity of climate hazards, especially lower
frequency, high-impact events that typically have the highest potential for causing
disruption. Current risk analysis practices and tools often fail to account for these
complexities.
This research investigates the impact of climate hazards on airports and how current risk
management practices address these challenges. In doing so, it introduces a new
framework for analysing the risk of climate hazards to airport systems, the Airport Climate
Risk Index (ACRI). The ACRI is a composite indicator addressing climate hazards, including
flooding (coastal and inland), extreme temperatures, storms, wind, heavy snowfall, and
drought/water scarcity. The index, designed as a self-assessment tool, seeks to empower
airports to identify, analyse, and assess their risks related to climate hazards. The
validation of the tool was carried out at four regional airports in the UK, providing insights
into current practices and challenges in managing climate hazards within existing
frameworks.
The research findings reveal a need for a change in practices to improve regional airports'
preparedness for climate-resilient development. Existing mitigation measures must be
evaluated for their effectiveness in addressing the increasing intensity and variety of
climate hazards. A more proactive approach is essential for integrating climate-related
risks into long-term planning, infrastructure development, and investment decisions.
Building more adaptability within the airport elements appears necessary to enable the
regional airports to grow sustainably.PhD in Transport System
Describing the complexities of developing an eVTOL’s turnaround concept of operations at vertiports
No full textUrban Air Mobility (UAM) represents a transformative shift in short-distance transportation, promising fast, sustainable and congestion-free travel using electric Vertical Take-Off and Landing (eVTOL) aircraft. While significant progress has been made in airspace integration and aircraft development, limited attention has been given to ground operations, specifically, the turnaround process at vertiports. This research addresses that gap by exploring the operational, infrastructural and regulatory complexities of eVTOL turnaround, with the aim of supporting the development of a Concept of Operations (ConOps). The study begins with a comprehensive analysis of eVTOL typologies, vertiport classifications and turnaround practices from both fixed-wing and rotary-wing aviation. A thematic literature review reveals a lack of standardised procedures and highlights emerging challenges related to infrastructure, charging, stakeholder roles and scalability. To gain deeper insight, six semi-structured interviews were conducted with stakeholders across consultancy, regulation, manufacturers, infrastructure and ground support services. These were analysed using thematic analysis supported by NVivo software. Findings indicate that eVTOL turnaround is not directly comparable to existing aviation models. Key differentiators include the dominance of electric charging or battery swapping, limited standardisation, the evolving regulatory environment and the need for automation. Stakeholders identified major challenges in assigning responsibilities, ensuring coordination and integrating safety protocols, particularly under constraints of infrastructure size and electricity availability. The study concludes that the development of a flexible, scalable turnaround ConOps is essential for the viability of UAM. While current uncertainties limit the finalisation of standard procedures, early planning and stakeholder engagement can facilitate safer and more efficient operations.MSc in Airport Planning and Managemen
A systems level framework for postharvest physiology and quality preservation
No full textThe postharvest phase is critical for determining the quality, nutritional value, and market viability of fresh produce, yet global losses remain substantial, often exceeding 40%. This perspective aims to establish an integrated framework for understanding postharvest physiology and guiding sustainable quality preservation strategies. Deterioration is driven by complex molecular and physiological transformations, including ripening, senescence, and oxidative stress. Understanding these mechanisms is paramount for developing effective loss and waste reduction strategies. Metabolomics provides a systems level view of these changes, enabling the large scale profiling of small molecules and the identification of valuable biomarkers for quality loss, chilling injury, and senescence. Shifts in primary metabolites (sugars, organic acids) and the accumulation of ‘off aroma’ volatiles (ethanol, acetaldehyde) are critical indicators of decline. Also, preharvest factors (e.g. regulated deficit irrigation, signalling molecule application) fundamentally influence postharvest metabolic states by enhancing antioxidant capacity and delaying senescence. Molecular regulation, orchestrated by hormonal signalling (ethylene, abscisic acid) and transcription factors, underpins these shifts. Interventions focus on sustained redox homeostasis, often achieved through the exogenous application of ecofriendly signalling molecules like salicylic acid to upregulate enzymatic and non-enzymatic antioxidant systems. Integrating multi-omics technologies (metabolomics, transcriptomics) facilitates the identification of molecular targets for these interventions and supports predictive modelling for optimising storage conditions. Translating these integrated insights into sustainable, biomarker based, farm to fork strategies is essential for enhancing food security and mitigating global greenhouse gas emissions associated with food loss.Frontiers in Plant Scienc
How strategic intent shapes the beliefs and behaviours of senior managers: evidence from a medical technology company.
No full textBowman, Cliff - Associate SupervisorThis study employed the critical incident technique to examine how strategic intent shaped the behaviours and beliefs of senior managers in a medical technology company undergoing change. Using this evidence, I contribute a model of the organizational effects of strategic intent, which shows how strategic intent is realized in organizations. In doing so, I also contribute a foundational definition of strategic intent, grounded in the literature employing the concept, but also informed by Action Philosophy. Together, these elements form a common basic theory of strategic intent that brings clarity and coherence to the disparate but related conversations about strategic intent in the literature. Finally, I revisit and add nuance to the resource allocation process and strategic renewal literatures.PhD in Leadership and Managemen
Immersed boundary method with improved implicit direct-forcing for fluid–structure interaction problems
No full textAn 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
HSI and ML for non-destructive pistachio quality assessment: influence of location and irrigation on nutrient and fat composition
No full textPistachio quality is a major determinant of market value, particularly in Mediterranean environments strongly influenced by irrigation and climate. This study evaluated effects of orchard location and irrigation on pistachio nutritional content and assessed VIS–NIR hyperspectral imaging coupled with machine-learning techniques as a non-destructive predictive approach. Field experiments were conducted in 2022 in two commercial orchards in Castilla y León, Spain, under control and high-irrigation treatments. A total of 2818 pistachio kernels were analysed using a portable VIS–NIR hyperspectral camera (400–1000 nm). Mean spectra were extracted for each nut, pre-processed using standard normal variate correction, and linked to reference measurements of minerals, proximate composition and fatty acids. Partial Least Squares regression, Support Vector Regression and Extra Trees Regressor models were calibrated and validated to predict quality parameters from spectral data. Location, irrigation and their interaction significantly affected most nutritional and lipid traits. Pistachios from Moraleja de las Panaderas showed higher nitrogen, phosphorus, protein, ash and oleic acid contents, whereas samples from La Seca exhibited relatively higher sodium and linoleic acid levels. Increased irrigation enhanced the accumulation of several minerals and saturated fatty acids. Among the evaluated algorithms, Partial Least Squares regression provided the most consistent performance, accurately predicting nitrogen (R2 = 0.75), zinc (R2 = 0.81), oleic acid (R2 = 0.91), linoleic acid (R2 = 0.87), ash (R2 = 0.81), carbohydrates (R2 = 0.87) and humidity (R2 = 0.84). Overall, VIS–NIR HSI with machine learning enables non-destructive, data-driven optimisation of pistachio irrigation management.This work was funded by MCIN/AEI/10.13039/501100011033 and European Union « NextGenerationEU»//PRTR, grant number RYC2021-033890. Co-financed by FEADER funds and Junta de Castilla y León (Spain).Food Contro
Integration of Physical and Psychological Human Data into Digital Human Modelling for Manufacturing System Design
No full textIndustry 4, the current industrial revolution, is bringing an increase in digitisation
to manufacturing. It involves, in part, a move towards using the digital human
modelling (DHM) capabilities in computer aided design (CAD) programs to design
and monitor products, workstations, and the new technology being introduced
into manufacturing working environments. DHM in CAD involves modelling the
impact manufacturing products and environments have on those who work in and
with them. At present, the focus of CAD programs with integrated DHM tools is
the physical impact of manufacturing environments on workers or operators;
psychological impacts, however, are missing. This thesis aimed to identify and
establish psychological parameters that could improve the capability of DHM for
manufacturing system design.
Two studies identified psychological equations for integration into DHM CAD, the
first established an equation between physical strain and mental workload. This
study was preceded by an investigation into the effectiveness of an inertial motion
capture suit to identify an effective means of measuring physical strain. The
second study investigated the effect of human robot collaboration on perceived
trust, workload, and mood, when manipulating robot speed. A predictive equation
could only be established for trust; and this equation was integrated into a CAD
program, and the reliability was assessed using an experimental mock-up of an
Airbus installation process. The equation when integrated into the CAD program
was able to successfully predict the trust response of participants in the reliability
experiment and, therefore, achieved the aim of this thesis. The implications and
limitations of the studies are discussed.PhD in Aerospac