PhD and MSc by research theses (SATM)
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Item Open Access Creating a framework for community integration of urban air mobility.(Cranfield University, 2022-03) Organ, Aaron John; Mason, Keith; Rothe, HenrikTechnological advancements in propulsion systems, alternative fuel, battery power and storage, and autonomy have led to the development of a new generation of aircraft. These enabling technologies inclusive of Small Unmanned Aircraft Systems (sUAS), Large Cargo Unmanned Aircraft (LUCA), and electric Vertical Take-off and Landing (eVTOL) or electric Conventional Take-off and Landing (eCTOL) aircraft fall under the umbrella term of Advanced Air Mobility (AAM). The current literature, in addition to regulators and the industry, is heavily focused on the aircraft and technology integration. This research contributes to a literature gap concerning ground infrastructure and community integration of AAM. The research aims to provide a framework of next steps relevant to state and city planners and policy makers. Subject matter experts from key AAM stakeholder groups were consulted through the execution of semi-structured interviews to produce a rich dataset of the issues and challenges of integrating AAM into the state and city’s transportation systems. The systematic approach of thematic analysis was used to identify top themes and sub-themes. The results identified AAM success keys, potential use cases, anticipated benefits of AAM, anticipated obstacles to AAM adoption, and stakeholder roles at the city, state, and federal level. These results have provided a framework for cities and states of what to do in the initial phases to integrate Advanced Air Mobility technologies into their existing transportations networks for a more sustainable and robust system.Item Open Access Development of a framework to estimate the software obsolescence resolution cost of custom build real-time software.(Cranfield University, 2022-01) Rajagopal, Sanathanan; Erkoyuncu, John Ahmet; Roy, RajkumarSoftware plays an important role in the defence sector. Almost every project in defence has got software with various degrees of complexity and dependencies. Software obsolescence is one of the key cost drivers which has historically been assessed as part of the maintenance cost due to the lack of data/information and due to the fact that there are no tools, techniques, or framework to help with the software obsolescence management. Therefor it is key for the industry and Defence sector to address software obsolescence and to find an approachable way to counter the effect of software obsolescence. The aim of this research is to develop a software obsolescence cost analysis framework to predict the software obsolescence resolution cost of custom build real time software at early stages of the product life cycle. For the accomplishment of the aim, an extensive literature review on software obsolescence and its related themes was undertaken, a systematic case study with online survey corroborated the findings and revealed the current practices in the UK Defence sector. Further collaboration with 35 experts from industries led to undertaking a cognitive case study to enable the iterative development of Software Obsolescence Cost Analysis Framework. This was demonstrated by applying the framework to five case studies as part of expert validation. The novelty of this research is that it tries to solve an issue with significant real- world impact for which very little work exists with lots of real-world inputs from SME and real case studies. Cognitive case study with software experts is unique and has never attempted before to solve this issue. The research comes up with a novel way to quantify the costs for the very first time with strong input from primary data sources. The key limitation of the research is in the unavailability of any historic technical data.Item Open Access A framework for enhancing knowledge sharing through social media in higher education institutions in the KSA.(Cranfield University, 2021-08) Alshalaan, Mohamed Nasser R.; Salonitis, Konstantinos; Patsavellas, JohnSocial media tools have changed the way individuals and academics impart, share content, inter-face, and team up. These days, social media is turning into an important stage for encouraging knowledge sharing and correspondence. The current research focuses on a framework for enhancing of the use of social media for knowledge sharing in higher education institutes (HEIs) in the Kingdom of Saudi Arabia (KSA) by using knowledge-sharing models and theories. The proposed framework was validated in the KSA academic sector. This research used semi-structured interviews with 31 participants from various departments in HEIs. The quantitative data were analysed using descriptive and inferential statistics. The qualitative data were analysed using a thematic analysis approach. The research identifies the factors influencing knowledge sharing through social media based on three aspects: individual, organisational, and technological dimensions. The contribution of this research includes a new framework derived from previous models and theories to investigate the potential factors that influence the use of social media for knowledge sharing. The interpretive structural models were applied based on the factors from the literature review and the findings from interviews. The findings lead to the development of a framework for the development of the knowledge- sharing process through social media in KSA HEIs. The proposed framework was validated using experts’ feedback. An interpretive structural model (ISM) as presented for a better understanding of the relationships among the critical factors. The ISM model contributed to the development framework of knowledge-sharing factors through social media. The proposed framework has the ability to identify potential factors and improve the knowledge-sharing process through social media. This research will help educational institutions to know how to support the use of social media tools for knowledge-sharing purposes by focusing on critical factors.Item Open Access Caught in the act: The structural pathway of liquid metals to vitrification monitored in situ by synchrotron X-ray diffraction.(Cranfield University, 2021-09) Stiehler, Martin E.; Georgarakis, Konstantinos; Jolly, Mark R.When a metallic melt is undercooled fast enough below its liquidus temperature, crystallisation can be avoided and a metallic glass, i.e. a metallic solid with amorphous structure, be formed. This kind of solidification is called vitrification. The prerequisites for this phenomenon are still not clear. An extensive review of the available relevant literature was carried out. To reveal the structural changes taking place at the atomic scale during undercooling and vitrification, data obtained by ultrafast synchrotron X-ray diffraction during aerodynamic-levitation experiments of different metallic-glass forming liquids was analysed. The complete pathway from temperatures well above the liquidus temperature during undercooling and vitrification down to temperatures well below the glass-transition temperature Tg was studied. During undercooling, a non-linear evolution of structural metrics in real as well as in reciprocal space takes place. Especially the height of the first maximum in the structure factor can be described by a structural analogue to the Curie-Weiss law. This behaviour was also found in published data re-analysed here. Indications of universal behaviour among the investigated alloys below a certain temperature as well as for a liquid-liquid crossover in Ti₄₀Cu₃₄Pd₁₄Zr₁₀Sn₂ were found. Small differences in the temperature dependence of the structural behaviour among the different alloys are possibly related to their different glass-forming abilities. To facilitate the analysis of the real-space structure the novel concept of the anti-shell was introduced. Temperature affects different length scales differently. Below Tg the structural behaviour is dominated by the Debye-Waller factor as well as by normal thermal-expansion behaviour. Above Tg an apparent negative thermal expansion of the first nearest-neighbour distance can be attributed to the influence of the structure-forming processes. In addition to short- and medium-range order, a third structural range for distances beyond the third nearest-neighbour is proposed. A disordering of the atomic structure of metallic glasses by the introduction of further alloying elements, facilitated by emergent effects among the components, could be demonstrated. The importance of the influence of global electronic interactions on structure formation was shown as well as their limitation to distances beyond the third nearest-neighbour.Item Open Access Structural dynamics and crack propagation behaviour under uniform and non-uniform temperature conditions.(Cranfield University, 2022-02) Kamei, Khangamlung; Khan, Muhammad Ali; Starr, AndrewThe robustness and stability of machinery depend on structural integrity. This stability is, however, compromised by aging, wear and tear, overloads, and environmental factors. A study of vibration and fatigue crack growth for structural health monitoring is one of the core research areas in recent times. The research is yet to input sufficient explanations about the dynamic behaviour of the structure under distributed temperature. The structural dynamics can be influenced by material microstructure, temperature distribution, and duration of exposure to the thermal environment. The applied temperature can cause significant variations in the modal response. The existing studies are limited concerning temperature change and compel extensive investigation in a crack and uncracked condition. In this research, the structural dynamics and fatigue crack propagation behaviour when subjected to thermal and mechanical loads have been studied. It investigates the modal parameters of uncracked and various cracked specimens under uniform and non-uniform temperature conditions. An analytical model considering the effective length of the beam is developed to analyse the modal response of the beam. Then, the model is modified to enumerate the modal behaviour of the beam in the presence of crack. The model is validated by experimental and numerical approaches. The experimental evaluation is conducted by considering three heating rates to attain the required temperatures. In the first case, ramping at 2°C/min is assumed as a slow heating rate. While ramping at 5°C/min and 8°C/min are assumed as moderate and rapid heating rates respectively. The heating rates are considered to compare the structural response changes. A small variation on modal parameters is noticed for different heating rates and when the applied uniform temperatures are changed to non-uniform temperatures, especially at elevated temperatures. This signifies heating at different rates has a slight effect while measuring the dynamic response of any mechanical system. The results showed that changes in modal parameters of the beam are associated with the change in temperatures and heating rate. Furthermore, this research substantiates the fatigue crack propagation behaviour of pre-seeded cracks. The propagated crack depths are measured based on pixels contains in the crack. It is found that propagated crack depends on applied temperatures and associated mass. The appearance of double crack fronts and multiple cracks are observed. The multiple crack appearance seems due to the selection of pre-seeded crack shapes. Hence, the real crack and pre- seeded crack are distinct and need careful consideration in crack propagation evaluation.Item Open Access Bead shape control using multi-energy source (mes) for wire-based directed energy deposition (ded) process.(Cranfield University, 2021-11) Chen, Guangyu; Ding, Jialuo; Williams, Stewart W.Independent control of layer width and height is essential to achieve a simultaneous high build rate with precision net shape and thermal control independent from deposition shape in the wire-based directed energy deposition (w-DED) process. Bead shape control using a multi-energy source (MES) method was studied to achieve independent control of layer width height of a bead for the w-DED process. This study was carried out in three stages: First, a plasma transfer arc (PTA) energy density measurement was conducted. A split anode calorimeter (SAC) was applied for the measurement of PTA energy density. A laser beam with a well-defined energy profile was used to calibrate the calorimeter without the complications of arc instability. An optimised centred grounded SAC device was introduced to reduce arc distortion. More symmetric arc profiles were obtained. The dynamic thermal characterisation of a scanning laser (SL) was then studied using both experimental and numerical approaches. SL experiments were conducted with different oscillation frequencies and laser beam sizes. An innovative solution dependent convection boundary (SDCB) method was introduced to reduce the element amount of the finite element (FE) model. Results show that the quasi-steady state SL can be applied as an equivalent stationary energy source. Finally, an SL-PTA MES system was introduced to study the MES bead shape control, a PTA was employed in the front to create an initial melt pool and melt the feedstock wire, and an SL was used behind the PTA to reshape the melt pool and precisely control the bead width. A bead shape control strategy was proposed by using the wire feeding rate to control the layer height and the scanning width to control the layer width. The experiment results verified that the SL-PTA MES has independent control of layer width and height.Item Open Access Development of NI3AL corrosion resistant coatings for SS347 heat storage components in presence of molten nitrate salt.(Cranfield University, 2020-07) Yasir, Sarah; Aria, Adrianus Indrat; Endrino, José L.Climate change is an inevitable global issue with long term consequences for the sustainable development. It is a crucial time to review this climate issue with ensured determination. There is a need and demand for alternative sources to generate power rather than the conventional burning of fuels due to impact on environment. Renewable energy sources are those natural reserves that are refilled continually, including wind, solar, biomass and geothermal. A number of technologies have been developed to use solar energy for power generation. Among them, an important feature of concentrated solar power plants is the potential to incorporate thermal storage. Thermal energy storage allows generation beyond sunset and in times of cloud cover. Several possibilities for heat transfer fluid and thermal energy storage have been identified. From a wide range of materials, molten nitrate salt is selected because of adequate heat storage and transfer capability. Different approaches to prolong life by suppressing corrosion have been suggested in the literature, coating is a promising option because coatings are believed to provide shield to suppress corrosion. Among different coatings, nickel aluminide has been claimed to possess high-temperature mechanical strength and it has a remarkable oxidation resistance performance as substrate component. Moreover, nickel aluminide has low solubility in the molten nitrate salt. Ni₃Al coatings are much preferred to be used as corrosion resistant coatings as they possess strength at high temperature, oxidation protection and creep properties. Among different deposition techniques, plasma spray has been identified as most applicable because it is versatile, adaptable, cost effective. It also has high deposition rate, deposition efficiency and less environmental impact, more importantly it is easy to scale up. Corrosion behaviour of stainless steel 347 (SS347) and Ni₃Al coated SS347 was investigated in molten nitrate salt (60wt% NaNO₃ + 40wt% KNO₃) immersion at 565oC for 500 hours intervals up to 3000 hours. A growth of stratified oxide layers was observed on SS347 sample surface comprising of NaFeO₂ , Fe₂ O₃ and Fe₃O₄ . The Ni₃Al coated SS347 samples were observed to undergo rapid oxidation within first 500 hours. Apparent Mass change for bare SS347 was 4 mg/cm²/yr, equivalent to oxide growth rate of ~ 5 µm/yr. Mass change for Ni₃Al coated SS347 was 29.8 mg/cm²/yr, equivalent to oxide growth rate of ~ 44.6 μm/yr for first 500 hours and 0.5 mg/cm²/yr, equivalent to oxide growth rate of ~ 0.7 μm/yr for 500 to 3000 hours. The results presented in this study suggest that Ni3Al coating supresses the formation of oxide layers on the surface of stainless- steel substrates and can be used to suppress corrosion in presence of molten nitrate salts. The fact, that Ni₃Al coated SS347 gives mass change of one order of magnitude lower than the bare SS347, it means that these coatings can be used to prolong the lifetime of bare SS347 in molten nitrate salt at 565oC, which is of relevance to thermal energy storage applications. The Engineering Doctorate portfolio is structured as an innovation report and five submissions. A personal profile and a report on international industrial placement are also included in the portfolio.Item Open Access Knowledge-driven business model canvas for business development of SMEs in the food sector in the gulf cooperation council.(Cranfield University, 2021-02) Alharbi, Bandar Fahad Mohammad; Al-Ashaab, Ahmed; Fan, Ip-ShingSmall and mid-size enterprises (SMEs) are the core engine of most economies around the world. Empowering SMEs with the right tools, especially those utilised to formulate business models, would help them thrive more successfully. This study aims to provide such business development support tools to the food sectors SMEs of the GCC. This research focuses on the SMEs in the Gulf Cooperation Council (GCC) processed food sector. First, an extensive literature review was conducted on business development and business development tools, the business models. It was found that the Business Model Canvas is the most advanced tool in the market, yet the model is not fully exploited in terms of business development and growth. A field study involving 36 companies within the GCC region's food industry was conducted. The findings indicated three main problems faced by SME’s: product-market-fit, business planning and finance. Hereafter, Lean start-up was applied in a case study on a frozen yogurt producer from the region. The findings from the case study showed that the lean start-up approach minimises the product-market-fit problem and, hence, provides a more explicit structure for business planning and finance. Furthermore, the case study findings were presented to six industry practitioners to evaluate the lean start-up method. Based on their evaluation; the model was modified to incorporate market regulations as an additional block. A set of measurement (KPI’s) was added to the model to develop a revised model named the Knowledge-Driven Business Model Canvas (KD-BMC). Finally, the KD-BMC was validated through a case study on two companies in the food industry in Saudi Arabia and further evaluation was gained from six experts in the field. Results of validation were discussed and concluded in the final chapter of this research.Item Open Access Aeroelastic analysis on a multi-element composite wing in ground effect using fluid-structure interaction.(Cranfield University, 2021-08) Bang, Chris Sungkyun; Temple, Chris; Konozsy, Laszlo Z.The present research focuses on an advanced coupling of computational fluid dynamics (CFD) and structural analysis (FEA) on the aeroelastic behaviour of a multi-element inverted composite wing with the novelty of including the ground effect. Due to the elastic properties of composite materials, Formula One (F1) car’s front wing may become flexible under fluid loading, modifying the flow field and eventually affecting overall aerodynamics. This research investigates the influence of elastic behaviour of the wing in ground proximity on the aerodynamic and structural performance by setting up an accurate the Fluid-Structure Interaction (FSI) modelling framework. A steady-state two-way coupling method is exploited to run the FSI simulations using ANSYS, which enables simultaneous calculation by coupling CFD with FEA. A grid sensitivity study and turbulence model study are preferentially performed to enhance confidence of the numerical approach. The FSI study encompasses everything from basic examination and measurement of the interaction phenomena using a single and double element inverted wing to the creation of a multi-objective wing design optimisation procedure. The computational results obtained from FSI simulations are assessed and compared with the experimentation with respect to surface pressure distribution, aerodynamic associated forces, and wake profiles. Concerning structure layups, ply orientation and core materials, the effect of various composite structure configurations on the wing performance is extensively studied. An efficient and unique decomposition-based optimisation framework utilising the response surface model is provided based on the aero-structural coupled analysis in order to enhance the wing design process' accuracy and efficiency while tackling aeroelastic phenomena.Item Open Access Development of a CFRTP manufacturing method to improve low velocity impact resistance of aerospace structures.(Cranfield University, 2020-08) Delporte, Yoan; Ghasemnejad, Hessam; Webb, PhilA continuous carbon fiber reinforced Polymer was manufactured using a Fused Deposition Modelling method. Current Fused Deposition Modelling machine are not able to manufacture Carbon Fiber Reinforced Thermoplastic Polymer composite therefore modification and novel designs needed to be made and integrated to the Fused Deposition Modelling machine to achieve a final product. To investigate the benefits of our composite a comparison with available composites on the market composed of similar materials needed to be performed. We investigated the different aspect of the requirements needed to manufacture test samples. We focused on manufacturing method able to integrate continuous Carbon Fiber simultaneously to a thermoplastic. In the slicing software a custom g code sequence has been developed to forward the continuous Carbon Fiber through the Bowden tube to the hotend. This procedure allowed the hotend to move freely between the layup of the printed part. Also C code library has been developed to analyse the geometry of the part to recognise the amount of Carbon Fiber, which needs to be pushed through the Bowden tube connected to the hotend. We investigated the mechanical properties as well as the process parameters of the individual materials used to manufacture our Carbon Fiber Reinforced Thermoplastic Polymer samples. In addition Carbon Fiber Reinforced Thermoplastic low velocity impact samples have been produced to investigate the potential of our composite in comparison to available products on the marker like Short Carbon Fiber Polyamide filaments. The low velocity performances of the Continuous Carbon Fiber Thermoplastic Polymer samples have been promising compared to conventional Short Carbon Fiber Polyamide samples. The advantages of using an Fused Deposition Modelling machine to manufacture composites is the ease to choose between numerous fiber orientations, which a significantly important feature for impact applications. In addition a potential case study for aerospace structure applications of our Carbon Fiber Reinforced Thermoplastic Polymer will be investigated and discussed. The novelty behind this is research is in the coding sequence allowing the fiber cutting system to trigger a the a specific moment in order to integrate the necessary amount of fiber according to the distance of the hotend travelled on the heat bed. Another novelty is in the unique servo actuated fiber cutting system using a specific cutting mechanism. The contribution to the knowledge is the study of the behaviour of a thermoplastic composite under low velocity impact. To investigate the effect of process parameters on a thermoplastic composite. To develop a novel cutting system and code control. Vibration cancellation method for even and continuous integration of continuous carbon fiber cutting method for precise carbon fiber cutting and integration to thermoplastic via Bowden extrusion system. Coding for the motherboard firmware as well as G code for the slicer have been optimised in order to produce quality samples. The effect of hardware on process parameters have been investigated though tensile tests. Low velocity impact performance of continuous carbon fiber polyamide has been also investigated and tested.Item Open Access Control for motion sickness minimisation in autonomous vehicles.(Cranfield University, 2021-06) Htike, Zaw Lin; Longo, Stefano; Velenis, EfstathiosAutomated vehicles are expected to push towards the evolution of transportation systems and exploit the use of vehicular technologies. This thesis investigates the fundamentals of motion planning for minimising motion sickness in transportation systems of higher automation levels. The optimum velocity pro le is sought for a predefined road path from a specific starting point to a final one within specific and given boundaries and constraints in order to minimise the motion sickness and the journey time. Motion sick- ness is minimised by taking the optimum trajectory and velocity profile for any given road path generated by the motion planner. The trajectory tracking controllers based on PID control method were able to track the reference trajectory with good performances. The trade-off between motion sickness and journey time was solved using the application of multi-objective optimisation by altering the weighting factors to find a compromise solution. The Pareto front representing the correlation between the two components is obtained and this front also allows user to select their preference driving style. From the three case studies, driving styles have a bigger impact on reducing motion sickness and journey time rather than vehicle speed and the road width. However, the effect of road width is negligible when travelling on longer road for the reduction of motion sickness and journey time. This finding is crucial considering the need for automated vehicles to drive on a fixed road path in respect to road safety and also to allow the employment of connected and automated vehicles in the future. Finally, an approach combining two optimisation algorithms, the optimal control problem and the k - є method, is applied successfully to seek the best trajectory profile that ensures the optimum compromise between motion comfort and driving behaviour, energy efficiency, vehicle stability, occupant's confidence to ride and journey time.Item Open Access Protection of magnesium alloys from corrosion using magnesium rich surfaces.(Cranfield University, 2021-06) Wang, Yading; Impey, Susan A.; Pidcock, AndrewMg alloys have great potential in engineering applications for saving energy consumption due to the high strength to weight ratio. Mg alloys are also biocompatible and biodegradable with biomedical applications such as orthopaedic and vascular implants. Controlling the corrosion of Mg alloy components is necessary to sustain their performance over the design lifespan. A low corrosion rate is also preferred for implants to mitigate negative effects such as hydrogen evolution during corrosion. Surface films can be used to control the corrosion of an Mg alloy effectively. In this work, Mg(OH)₂ coatings were deposited on Mg alloy substrates (AZ31 and ZM21) by hydrothermal (H.T.) steam treatment as a benchmark and subsequently by novel processing using electrochemical (E.C.) and additive treatment with an Mg²⁺ rich solution. The microstructures and compositions of the alloys are characterised both with and without coatings. Corrosion tests were conducted in various test solutions, including 3.5% NaCl, 0.9% NaCl and Hank's solutions. Electrochemical techniques and mass change measurement are used for the corrosion testing of initial exposure and longer-term immersion, respectively. The processing parameters of the electrochemical and additive methods were optimised based on the corrosion behaviour of the coated samples. This research shows that the Mg(OH)₂ based coating can enhance the corrosion protection of the Mg alloy substrates, with at least a 3 fold reduction in corrosion rates compared to uncoated substrates. Comparing hydrothermal coatings, the electrochemical and additive (EC+Additive) coatings not only show similar corrosion performance but also greater manufacturing flexibility and repairability with potential for further enhancement.Item Open Access Novel applications and stabilisation for widely wavelength modulated laser interferometry for precision dimensional metrology.(Cranfield University, 2021-11) Wiseman, Kieran; Kissinger, Thomas; Tatam, Ralph P.The need for precision dimensional metrological techniques is always increasing, including high precision displacement measuring metrology used to precisely and accurately position stages, components and machines. Laser interferometry is widely considered the most precise technique available for single dimensional displacement measurements, however extending this to multiple dimensions typically involves complex and costly interrogation systems. In this thesis, a series of novel multi-dimensional stage encoder designs and experimental results are presented as an application of a state-of-the- art metrological technique, that uses sinusoidal wavelength modulation and range-dependant signal processing to multiplex the signals from multiple interferometers into a single interferometric signal. Using range-resolved interferometry (RRI), a series of interferometers comprising measurements in multiple dimensions are multiplexed onto a single photodetector, which are then are independently and concurrently demodulated and evaluated. This technique is applied to novel designs for a 2-dimensional displacement encoder, a 3-dimensional displacement encoder and a dual-beam angle encoder, where unlike prior work which has typically required complex optical setups involving polarisation-sensitive optical components and detectors, uses only minimal, simple bulk optic components to evaluate multiple dimensions simultaneously. In this work, nonlinearities below 1 nm along with typical displacement noise levels below 0.4 nm/√Hz are presented for experimental results of ±50 µm controlled stage motions, showing results which are highly comparable to existing techniques. Further to this, in order to make high precision results with confidence, high-stability lasers are required. In non-modulated and weakly modulated wavelength regimes, there are a significant number of techniques available for laser stabilisation, for both short-term and long-term requirements and linked to highly stable references. However, for widely-wavelength modulated techniques such as RRI, where the modulation depth is several orders of magnitude greater than standard reference widths, the vast majority of existing techniques are either unsuitable or significantly less-effective. In this thesis, a novel technique for long-term stabilisation of a widely wavelength modulated laser to a high stability reference standard is presented. Introduced as "swept absorption line locking", the principle behind this technique, in addition to experiments to test the efficacy of this technique are presented. Included in this, is comparison to a highly-stabilised helium-neon laser, which is often considered a "gold-standard" for stability, where co-linear displacement measurements of a Michelson interferometer are performed and compared to determine the RRI evaluation wavelength. The results presented here show fractional stabilities as low as 6×10−⁸ over timescales of ∼1000 seconds using this novel stabilisation technique, and the comparison to the HeNe laser interferometer shows good agreement between the calculated RRI evaluation wavelength and the expected stabilised value within calculated uncertainties.Item Open Access A wavelet-based intrusion detection system for controller area network (can).(Cranfield University, 2021-05) Bozdal, Mehmet; Jennions, Ian K.; Samie, MohammadController Area Network (CAN), designed in the early 1980s, is the most widely used in-vehicle communication protocol. The CAN protocol has various features to provide highly reliable communication between the nodes. Some of these features are the arbitration process to provide fixed priority scheduling, error confinement mechanism to eliminate faulty nodes, and message form check along with cyclic redundancy checksum to identify transmission faults. It also has differential voltage architecture on twisted two-wire, eliminating electrical and magnetic noise. Although these features make the CAN a perfect solution for the real-time cyber-physical structure of vehicles, the protocol lacks basic security measures like encryption and authentication; therefore, vehicles are vulnerable to cyber-attacks. Due to increased automation and connectivity, the attack surface rises over time. This research aims to detect CAN bus attacks by proposing WINDS, a wavelet-based intrusion detection system. The WINDS analyses the network traffic behaviour by binary classification in the time-scale domain to identify potential attack instances anomalies. As there is no standard testing methodology, a part of this research constitutes a comprehensive testing framework and generation of benchmarking dataset. Finally, WINDS is tested according to the framework and its competitiveness with state-of-the-art solutions is presented.Item Open Access Strategic capacity planning framework for airport passenger terminal facilities.(Cranfield University, 2022-02) Waltert, Manuel; Pagliari, Romano; Jimenez Perez, EdgarFacility requirements describe how the capacity of a facility should be adjusted over time to meet the expected future demand levels. Practitioners use them to determine the strategic development of airport passenger terminal facilities. The generation of facility requirements is extraordinarily complex, since (i) airport strategic planning is subject to high levels of uncertainty due to the extremely long planning horizons considered, and (ii) investments in infrastructure are subject to irreversibility. This study presents a strategic capacity planning framework consisting of two modules, by means of which stochastically optimal facility requirements for airport passenger terminal facilities can be determined. The demand module is applied first. Its purpose is twofold: on the one hand, to create annual aggregated demand scenarios of an airport by means of geometric Brownian motion. On the other hand, to convert these scenarios into facility-specific design hour loads with the help of linear regression models. Subsequently, the capacity expansion problem module is used to determine conventional and flexible facility requirements that maximize the net present value of an airport passenger terminal facility. For this purpose, both conventional and flexible capacity expansion problem models, presented in the literature, are adapted to the needs of airport strategic planning. Subsequently, they are solved with evolutionary optimization algorithms. The framework is applied to a real-world planning example of the existing check- in facilities at Zurich Airport. The aim of the planning example is to compare flexible facility requirements with conventional facility requirements in terms of their economic value, and to investigate how sensitive the proposed models are to variations in several input factors. The results suggest that flexible facility requirements are generally more valuable than conventional facility requirements. Moreover, the models applied in this study respond to changes in input factors in a similar way to comparable models documented in the literature.Item Open Access Path tracking control of a multi-actuated autonomous vehicle at the limits of handling.(Cranfield University, 2021-06) Lin, Chenhui; Velenis, Efstathios; Longo, Stefano; Siampis, EfstathiosOver the past few decades, autonomous vehicles have been widely considered as the next generation of road transportation. As a result, relevant technology has been rapidly developed, and one specific topic is enabling autonomous vehicles to operate under demanding conditions. This requires the autonomous driving controller to have a good understanding of the vehicle dynamics at the limits of handling, and is expected to improve the performance as well as safety of autonomous vehicles especially in extreme situations. Furthermore, there has been application of techniques such as torque vectoring and four- wheel steering on modern vehicles as part of the driver assistance system, while such multi-actuation can be deployed on an autonomous vehicle in order to further enhance its performance in response to challenging manoeuvres and scenarios. This thesis aims to develop a real-time path tracking control strategy for an autonomous electric vehicle at the limits of handling, taking advantage of torque vectoring and four- wheel steering techniques for the enhanced control of vehicle dynamics. A nonlinear model predictive control formulation based on a three degree-of-freedom vehicle model is proposed for control design, which takes into account the nonlinearities in vehicle dynamics at the limits of handling as well as the crucial actuator constraints. In addition, steady-state references of steering inputs as well as vehicle states are generated based on a bicycle model and included in the control formulation to improve the performance. Two path tracking models with different coordinate systems are introduced to the control formulation, and compared to understand the more suitable one for the proposed path tracking purpose. Then the path tracking performance with different levels of actuation is investigated. According to the high-fidelity simulation results, the vehicle achieves the minimum lateral deviation with the over-actuation topology including both torque vectoring and four-wheel steering, which illustrates that the over-actuation formulation can enhance the path tracking performance by enduing the vehicle with the best flexibility as well as stability during operation at the limits of handling. Before being implemented on the vehicle, the performance of the proposed control strategy is further assessed with regards to real-time operation. After evaluating the control performance with different prediction horizons and sampling time, the most suitable setup is identified which compromises between the control performance and the capability of real-time execution. Finally, the control algorithm is implemented on a real vehicle for practical testing. The controller is tested in four different scenarios, and the results demonstrate that the proposed controller is capable of path tracking control and vehicle stabilisation for multi-actuated autonomous vehicles at the limits of handling. In general, this thesis has proposed a path tracking controller for autonomous vehicles which takes into account nonlinear vehicle dynamics at the limits of handling. Following some necessary simplification, the developed controller has been successfully deployed on a real vehicle in real time, and the control performance has been validated in several challenging scenarios. The controller proves itself to be able to improve the vehicle’s flexibility as well as to stabilise the vehicle at the limits of handling, and furthermore, it is able to accommodate relatively large side slip angles during the demanding manoeuvres as well.Item Open Access Developing a data and knowledge management approach for Integrated vehicle health management.(Cranfield University, 2021-10) Alexslis Nyuyfoghan Maindze, Xxx Alexslis; Jennions, Ian K.; Skaf, ZakwanIn Integrated Vehicle Management (IVHM), research and engineering activities are conducted that generate large amounts of data and content. These activities include simulations, observations, derivation, experiments and referencing. However, IVHM still faces a range of data- and Knowledge Management (KM) challenges ranging from data accuracy to long-term availability for prognostic and diagnostic health management. IHVM is data-centric and therefore requires a robust data life cycle management to supports its data- and Knowledge Management activities. An understanding of the concept of KM is fundamental to addressing the IVHM data and knowledge management issues. In this regard, this thesis contextualises ‘Knowledge Management’ for IVHM by attempting to resolve the intellectual paradox that has characterised it over the years. It discusses the origins of Knowledge Management as a discipline and addresses its historical inconsistencies. This review of KM and its origins serves as a scoping study guiding a systematic review of data life cycle models. It reviews relevant standards and their role in the data life cycle. Guided by the V-Model, a Data Life Cycle Model is developed as a result and validated using a multi-technique approach combining peer review and expert insights obtained through a purposive survey. The model is then applied to IVHM centre Knowledge Management System development (KMS). The outcome includes an improved requirements gathering process and a solid foundation for resolving IVHM data and Knowledge Management challenges.Item Open Access Biomimetic polymer reactor: design and modulation of novel tandem catalysts.(Cranfield University, 2021-09) Wei, Wenjing; Chianella, Iva; Thakur, Vijay Kumar; Koziol, KrzysztofTandem catalysis can perform multi-step catalytic reactions in one-pot sequentially, which not only improves the efficiency of reactions significantly, but also decreases time, energy and the amounts of reagents needed. However, as there is always more than one active site (catalyst) in tandem reactors, it is critical to separate different sites and ensure each step is conducted individually. Moreover, it is often challenging to control the whole reaction processes due to the complexity of the systems. In this research, several bio-inspired catalytic reactors were proposed and developed to address the two challenges of site separation and smart control of tandem catalysis. First of all, the goal of sites separation has been achieved in this work through an enzyme-inspired molecularly imprinted polymer reactor MIP-Au-NP-BNPC and a core-shell structure catalytic nanoreactor AMPS@AM-Ag. Two molecularly imprinted cavities were created in MIP-Au-NP-BNPC. The different channels of the two catalytic sites in the reactor enabled different catalytic reactions to occur in different regions, resulting in the process of tandem reactions. As a result of the radial distribution of catalytic sites and mass transfer, the core-shell structure of AMPS@AM-Ag enabled the nanoreactor to perform different catalytic processes sequentially. Hence, the nanoreactor demonstrated the ability to conduct tandem catalysis with successful site separation. Then a biomimetic switch was introduced into the reactor to achieve the smart control of the catalytic process. Firstly, a new type of catalytic reactor consisting of a three-layer mussel-inspired polymer, MIP-AgPRS, was developed. The smart switchable layer composed of mussel-inspired self-healing copolymer was prepared between two MIP layers. This middle smart layer was able to react to different temperatures, permitting either simple or tandem reactions by closing and opening the access of the intermediate products. Secondly, a bilayer polymer reactor, DPR, composed of two different temperature-sensitive polymer layers was prepared. The two functional layers were not only able to respond to different specific temperatures, but each also contained different catalytic sites. Because of the two different phase transition processes of the two layers, the polymer reactor demonstrated to be able to perform simple/tandem catalysis in different temperature regions. As a result, this new type of bilayer polymer reactor was capable of achieving smart control of the tandem reactions. Finally, a three-layer switchable polymer reactor, PRS, with two MIP layers and a PNIPAM-PAM switchable layer in the middle was prepared. In an aqueous environment, when the temperature was low (lower than 47 °C), it exhibited an open access (hydrophilic condition), while when the temperature was high (higher than 47 °C), it became closed (hydrophobic condition). Furthermore, a comonomer (AM) was introduced in the middle layer with different ratios to adjust the responsive temperature range, enabling a more comprehensive range of practical uses. Therefore, a fast responsive and stable polymer reactor with self- controlled catalytic property was obtained. By preparing different types of new catalytic reactors, the research carried out here has shown the ability to achieve a smart control of the tandem catalysis while separating the catalytic sites effectively. Therefore, this study has highlighted new solutions to address the challenges present in tandem catalysis and has provided novel inspiration on how to exploit functional polymers while performing complicated catalytic reactions.Item Open Access The design and development of the miniaturised active thermography for in-situ inspection of industrial components.(Cranfield University, 2021-06) Du, Weixiang; Zhao, Yifan; Addepalli, PavanNondestructive testing (NDT) is a common and reliable method for the detection of surface and subsurface defects. However, due to the increasing integration and complexity of industrial components and systems, the problem of mismatching of size and volume between the existing inspection unit and the targeted object has limited the applicability of NDT techniques. Especially for geometrically intricate systems, the deployment of NDT devices for in-situ inspection has become a major challenge. Addressing the challenge of inaccessibility and inapplicability, this research proposes a miniaturised active thermography (MAT) system, featured with a small-size and low-cost thermal sensor, and a portable optical heat excitation source. A novel spatial resolution enhancement for a thermogram (SRE4T) system, which includes an infrared (IR) sensor, an XY movement stage and a super-resolution image enhancement method, is also proposed to address the low spatial resolution of the miniaturised sensor without upgrading the sensor. Moreover, dedicated data analysis approaches to evaluate defects are proposed considering the degraded signal quality. Compared with existing non-miniaturised inspection systems, the proposed system is evaluated quantitatively and qualitatively by testing samples with different materials, structures, and a variety of defects. An accessibility test is designed and conducted to evaluate the proposed system’s performance to access geometrically intricate space. The results show that the proposed system can work effectively for the degradation assessment of composite laminates, and also has enhanced accessibility and applicability of deployment for geometrically intricate systems and narrow space targets. It is observed that the data quality for composite materials seems to be more reliable and quantifiable than metal due to the relatively low sample rate of the sensor and the high thermal conductivity of the metal component. The SRE4T system can significantly improve the spatial resolution of miniaturised sensors, although it has not been used for active thermography at the present stage. The current miniaturised IR cameras feature low spatial resolution and low Signal-to-Noise Ratio, which leads to the poor performance of most of the current data analysis methods on these sensors. We propose an effective analytics framework including data processing, image processing and feature extraction to reduce the influence of noise and enhance the detectability of damage.Item Open Access Efficient modelling and evaluation of rolling for mitigation of residual stress and distortion in wire arc additive manufacturing.(Cranfield University, 2021-08) Gornyakov, Valeriy; Ding, Jialuo; Sun, YongleWire and Arc Additive Manufacturing (WAAM) is a promising technology for manufacturing large-scale parts with low costs and short lead time. One of the main challenges in applying WAAM in industry is the effective control of residual stress and distortion. It has been found that high-pressure inter-layer rolling can effectively mitigate the residual stress and distortion of WAAM components. However, the mechanism behind the mitigation efficacy is of a complex nature and has not been well understood. Finite element analysis (FEA) has proven to be a reliable and accurate method for simulating the thermo-mechanical process. The FEA simulation of large-scale inter-layer rolling is challenging due to the high computational cost and complicated coupling between WAAM and rolling. This research is based on efficient models for simulating WAAM deposition and rolling processes, and their combination for large-scale structures. The efficient modelling method is developed using a reduced-size model to determine the steady-state solution, and then mapping the solution to a full-size structure for further analysis. This method is successfully applied to study the evolution of residual stress and plastic strain during the post-build and inter-layer rolling of WAAM deposited walls. The numerical predictions are verified with experimental results. Cyclic formation of tensile residual stress occurs during the WAAM deposition, whereas inter-layer rolling counteracts the development of the residual stress. The effectiveness of roller designs is studied for reducing residual stress of the WAAM process. Compared with a flat roller, a slotted roller can induce greater longitudinal plastic strains and more effectively reduce the tensile residual stress in the WAAM wall. Removal of the clamps only results in a slight redistribution of residual stress in the post-build and inter-layer rolled WAAM components, since the rolling mitigates most of the tensile residual stresses caused by WAAM. To enhance the manufacturing efficiency, stacked-layers rolling can replace inter- layer rolling for RS and distortion mitigation in tall WAAM parts. Influences of main process parameters, such as rolling load and roller-to-component friction, on mitigation of RS and distortion are also studied. Finally, based on the understanding gained through the simulations, recommendation of an optimal rolling strategy is made for future industrial application.