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Item Open Access 2D linear friction weld modelling of a Ti-6Al-4V T-joint(Technological Educational Institute of Eastern Macedonia and Thrace, 2015) Lee, Lucie Alexandra; McAndrew, Anthony; Buhr, Clement; Beamish, K. A.; Colegrove, Paul A.Most examples of linear friction weld process models have focused on joining two identically shaped workpieces. This article reports on the development of a 2D model, using the DEFORM finite element package, to investigate the joining of a rectangular Ti-6Al-4V workpiece to a plate of the same material. The work focuses on how this geometry affects the material flow, thermal fields and interface contaminant removal. The results showed that the material flow and thermal fields were not even across the two workpieces. This resulted in more material expulsion being required to remove the interface contaminants from the weld line when compared to joining two identically shaped workpieces. The model also showed that the flash curves away from the weld due to the rectangular upstand "burrowing" into the base plate.Understanding these critical relationships between the geometry and process outputs is crucial for further industrial implementation of the LFW process.Item Open Access 2D ultrathin carbon nanosheets derived from interconnected Al-MOF as excellent hosts to anchor selenium for Li-Se battery(Elsevier, 2019-05-29) Jin, Wen-Wu; Li, He-Jun; Zou, Ji-Zhao; Inguva, Saikumar; Zhang, Qi; Zeng, Shao-Zhong; Xu, Guo-Zhong; Zeng, Xie-RongAlleviating volume expansion of the electrodes and improving utilization of the active materials have become key problems restricting a successful commercialization of lithium-selenium batteries. In this paper, a 2D ultrathin carbon nanosheets derived from interconnected MOF is designed for the first time. Such carbon nanosheets are composed by parallel stacked 2D sub-units, and this unique hierarchical porous architecture is beneficial for buffering the volume expansion and for improving the utilization rate of the active materials. Therefore, the cathode displays an excellent cycling stability with a reversible capacity of 347.3 mAh g−1 at 2 C after 240 cycles.Item Open Access 3-3 piezoelectric metamaterial with negative and zero Poisson's ratio for hydrophones applications(Elsevier, 2018-12-18) Khan, Kamran Ahmed; Khan, Muhammad AliThis study presents the electromechanical properties of the 3-3 piezoelectric metamaterial based on variants of honeycomb (HC) structure. Three kinds of three-dimensional (3D) elastically anisotropic and piezoelectrically active HC structures were introduced, namely, conventional HC (3D-CHC), a re-entrant HC (3D-RE) and a semi-re-entrant HC (3D-SRE). Highly porous 3D finite element models of the mentioned three kinds of metamaterials were developed and the role of ligament orientation on their effective elastic, piezoelectric and dielectric properties was completely characterized. The intrinsic symmetry of HC structure was utilized and simplified mixed boundary conditions equivalent to periodic boundary conditions were recognized. In comparison to their bulk constituent, all the 3-3 type piezoelectric HC networks exhibited an enhanced response, especially for the longitudinal poling. The normalized figures of merit show a mild dependence on the angle θ and the underlying deformation mechanisms associated with the zero, positive and negative Poisson’s ratios. Figures of merit such as hydrostatic strain coefficient (dh" role="presentation">), the hydrostatic figure of merit (dh.gh" role="presentation">) and the acoustic impedance (Z" role="presentation">) reached their best values at small angles, i.e., θ = 30°. Longitudinally poled networks exhibited four order of magnitude increase in their hydrostatic figure of merit (foam to solid ratio >10,000) and one order of magnitude decrease in the acoustic impedance indicating their applicability for the design of hydrophones.Item Open Access A 3D CFD analysis of flow past a hipped roof with comparison to industrial building standards(Techno Press, 2022-06-25) Khalil, Khalid; Khan, Huzafa; Chahar, Divyansh; Townsend, Jamie F.; Rana, Zeeshan A.Three-dimensional (3D) computational fluid dynamics (CFD) analysis of flow around a hipped-roof building representative of UK inland conditions are conducted. Unsteady simulations are performed using three variations of the k-ϵ RANS turbulence model namely, the Standard, Realizable, and RNG models, and their predictive capability is measured against current European building standards. External pressure coefficients and wind loading are found through the BS 6399-2:1997 standard (obsolete) and the current European standards (BS EN 1991-1-4:2005 and A1:20101). The current European standard provides a more conservative wind loading estimate compared to its predecessor and the k-ϵ RNG model falls within 15% of the value predicted by the current standard. Surface shear stream-traces and Q-criterion were used to analyze the flow physics for each model. The RNG model predicts immediate flow separation leading to the creation of vortical structures on the hipped-roof along with a larger separation region. It is observed that the Realizable model predicts the side vortex to be a result of both the horseshoe vortex and the flow deflected off it. These model-specific aerodynamic features present the most disparity between building standards at leeward roof locations. Finally, pedestrian comfort and safety criteria are studied where the k-ϵ Standard model predicts the most ideal pedestrian conditions and the Realizable model yields the most conservative levels.Item Open Access A 3D immersive discrete event simulator for enabling prototyping of factory layouts(Elsevier, 2015-10-27) Oyekan, John; Hutabarat, Windo; Turner, Christopher J.; Tiwari, Ashutosh; Prajapat, Neha; Ince, Nadir; Gan, Xiao-Peng; Waller, TonyThere is an increasing need to eliminate wasted time and money during factory layout design and subsequent construction. It is presently difficult for engineers to foresee if a certain layout is optimal for work and material flows. By exploiting modelling, simulation and visualisation techniques, this paper presents a tool concept called immersive WITNESS that combines the modelling strengths of Discrete Event Simulation (DES) with the 3D visualisation strengths of recent 3D low cost gaming technology to enable decision makers make informed design choices for future factories layouts. The tool enables engineers to receive immediate feedback on their design choices. Our results show that this tool has the potential to reduce rework as well as the associated costs of making physical prototypes.Item Open Access 3D modelling of Ti–6Al–4V linear friction welds(Taylor & Francis, 2016-12-05) McAndrew, Anthony; Colegrove, Paul A.; Buhr, ClementLinear friction welding (LFW) is a solid-state joining process that significantly reduces manufacturing costs when fabricating Ti–6Al–4V aircraft components. This article describes the development of a novel 3D LFW process model for joining Ti–6Al–4V. Displacement histories were taken from experiments and used as modelling inputs; herein is the novelty of the approach, which resulted in decreased computational time and memory storage requirements. In general, the models captured the experimental weld phenomena and showed that the thermo-mechanically affected zone and interface temperature are reduced when the workpieces are oscillated along the shorter of the two interface contact dimensions. Moreover, the models showed that unbonded regions occur at the corners of the weld interface, which are eliminated by increasing the burn-off.Item Open Access 3D-printed thermoplastic composite fasteners for single lap joint reinforcement(Elsevier, 2021-12-10) Li, Wenhao; Guo, Shijun; Giannopoulos, Ioannis K.; Lin, Minxiao; Xiong, Yi; Liu, Yiding; Shen, ZhengquanThis study presents findings for the strength and failure mechanism of a 3D-printed Continuous Carbon Fibre reinforced Onyx (CCF/Onyx) Thermo-Plastic Composite Fastener (TPCF) and a single lap-joint (SLJ) made of fibre/polymer composite reinforced by the TPCF. The study was carried out by numerical analysis and experiment methods including test sample design, manufacturing process and mechanical test. The 3D-printed fasteners were manufactured and tested in shear mode for two types of joining arrangement: fastened and hybrid bonded/fastened joints. Firstly, experiment was carried out for the TPCF fastened SLJ and the results show that addition of CCF in the Onyx matrix and post heat-treatment process could significant enhance the TPCF strength. The results was then benchmarked against a SLJ with steel fastening. The shear failure load of the SLJ reinforced by heat-treated CCF/Onyx TPCF of 8mm diameter was 36% lower than a SLJ reinforced by a steel bolt of the same size. Numerical model for progressive damage simulation was also created based on the failure theory from Puck and Schürmann achieving good correlation with the experimental data. Secondly, the TPCF fasteners were manufactured with two types of heat-treated countersunk head and pan head forming and used to reinforce bonded SLJ. The test results show that the bonded SLJ reinforced by the TPCF fastener of countersunk head is of 11.7% higher strength and an increase in ultimate deformation by 9.1% compared to a bonded SLJ reinforced by steel fastener of 5mm diameter. From the numerical and experimental study, it was noted that this was attributed to countersunk configuration to reduce out-out-plane bending and provide better crack arresting for the joint bonding.Item Open Access 4 Developing a framework to improve leadership performance in healthcare organisations: the case of the kingdom of Saudi Arabia(BMJ, 2018-10-31) Algarni, Namshan; McLaughlin, Patrick; Al-Ashaab, AhmedIn order to improve leadership performance and enhance effective leadership in the healthcare sector organisations in general and the KSA in particular, this study proposes a theoretical framework to address the way in which leadership competency strengthens the relationship between leaders and followers. This research uses a constructive-interpretive philosophical approach, applying a qualitative strategy to achieve its objectives. The study aimed to identify the factors that related to performance level, including enablers and inhibitors of performance improvement. This helped to build an initial understanding about the context of the project and hence, address the critical factors and aspects that could be influencing leadership performance improvement in the healthcare sector in Saudi Arabia in order to develop a framework with suggested interventions to improve the productivity in this vital sector. Sampling of this study is the Health affairs of the Ministry of the Saudi National Guard. NGHA has also become well known internationally, especially in successful conjoined twins separations.Item Open Access 4D printing of materials for the future: opportunities and challenges(Elsevier, 2019-10-16) Joshi, Siddharth; Rawat, Krishna; Karunakaran, C.; Rajamohan, Vasudevan; Mathew, Arun Tom; Koziol, Krzysztof K. K.; Kumar Thakur, Vijay; Balan, A.S.SThe concept of 4D printing is its formation of complex three-dimensional structures that have the ability to adopt different shapes and forms when subjected to different environmental stimuli. A few researchers simply view 4D printing as an extended technique of 3D printing or additive manufacturing with the added constraint of time. However, the unique shape change mechanism exhibited in this process is a combination of shape programming and the usage of smart active materials mostly polymers. This review article highlights the various smart materials, activation mechanisms and the shape-changing techniques employed in the 4D printing process. The potential of the shape-changing structures and their current applications in various biomedical and engineering fields is also explored. The article aims to emphasize the potential and viability of 4D printing and focused on providing an in-depth insight into the 4D printing process.Item Open Access 4D printing of smart polymer nanocomposites: integrating graphene and acrylate based shape memory polymers(MDPI, 2021-10-24) Chowdhury, Jaydeep; Anirudh, Premnath Vijay; Karunakaran, Chandrasekaran; Rajmohan, Vasudevan; Mathew, Arun Tom; Koziol, Krzysztof K. K.; Alsanie, Walaa F.; Kannan, Chidambaram; Balan, Arunachalam S. S.; Thakur, Vijay KumarThe ever-increasing demand for materials to have superior properties and satisfy functions in the field of soft robotics and beyond has resulted in the advent of the new field of four-dimensional (4D) printing. The ability of these materials to respond to various stimuli inspires novel applications and opens several research possibilities. In this work, we report on the 4D printing of one such Shape Memory Polymer (SMP) tBA-co-DEGDA (tert-Butyl Acrylate with diethylene glycol diacrylate). The novelty lies in establishing the relationship between the various characteristic properties (tensile stress, surface roughness, recovery time, strain fixity, and glass transition temperature) concerning the fact that the print parameters of the laser pulse frequency and print speed are governed in the micro-stereolithography (Micro SLA) method. It is found that the sample printed with a speed of 90 mm/s and 110 pulses/s possessed the best batch of properties, with shape fixity percentages of about 86.3% and recovery times as low as 6.95 s. The samples built using the optimal parameters are further subjected to the addition of graphene nanoparticles, which further enhances all the mechanical and surface properties. It has been observed that the addition of 0.3 wt.% of graphene nanoparticles provides the best results.Item Open Access 4D trajectory optimization of commercial flight for green civil aviation(IEEE, 2020-03-31) Tian, Yong; He, Xiuqi; Xu, Yan; Wan, Lili; Ye, BojiaFor the current development of green civil aviation, this study aims to optimize the green four-dimensional (4D) trajectory of commercial flight by taking into account conventional cost and environmental cost. Some fundamental models, efficient processing methodologies, and conventional objectives are proposed to construct the framework of trajectory optimization. Based on the environmental cost including greenhouse gas cost and harmful gas cost, green objective functions are presented. The A* algorithm and the trapezoidal collocation method are employed to optimize the lateral path and vertical profile for 4D optimization trajectory generation. A case study for the A320 from Barcelona Airport to Frankfurt Airport yields the results that the optimal costs can be obtained under different objectives and the total cost can be more optimized by adjusting the weights of environmental cost and conventional cost. The study builds an aided tool for 4D trajectory optimization and demonstrates that environmental factors and conventional factors should be taken into comprehensive consideration when constructing the flight trajectory in the future, as well as it can underpin the green and sustainable development of the air transport industry.Item Open Access A 4D-trajectory planning method based on hybrid optimization strategy for demand and capacity balancing(IEEE, 2021-11-15) Chen, Yutong; Xu, Yan; Hu, Minghua; Huang, Fei; Nie, QiTo effectively solve the Demand and Capacity Balancing (DCB) in future Trajectory-Based Operation (TBO) scenarios, this article first proposes a pre-tactical-and-tactical integrated Four-Dimensional Trajectory (4DT) planning framework. The framework decomposes large-scale 4DT planning into two stages, namely, the General 4DT (G4DT) planning in the pre-tactical stage and the Special 4DT (S4DT) planning in the tactical stage. A Hybrid Optimization Strategy (HOS) based planning method is designed for G4DT planning. In this method, the sequential decision architecture based on time window, heuristic strategy (greedy strategy) and optimization algorithm are combined to realize the fast trajectory planning of large-scale flights. In the optimization model based on continuous time, the nonlinear model is transformed into a linear model by constructing the flight conflict correlation matrix, which greatly improves the solving speed of the model. Real flight schedule data for French and Spanish airspace were used to verify the effectiveness and efficiency of the HOS method. This method is compared with Computer-Assisted Slot Allocation (CASA). The results show that the proposed method can effectively reduce the flight delay time and improve the flight on-time rate. Due to its fast operation speed, the proposed method has great potential to dynamically update the planning results according to the real-time air space operation status in actual operation.Item Open Access 5G aviation networks using novel AI approach for DDoS detection(IEEE, 2023-07-17) Whitworth, Huw; Al-Rubaye, Saba; Tsourdos, Antonios; Jiggins, JuliaThe advent of Fifth Generation (5G) technology has ushered in a new era of advancements in the aviation sector. However, the introduction of smart infrastructure has significantly altered the threat landscape at airports, leading to an increased vulnerability due to the proliferation of endpoints. Consequently, there is an urgent requirement for an automated detection system capable of promptly identifying and thwarting network intrusions. This research paper proposes a deep learning methodology that merges a Convolutional Neural Network (CNN) with a Gated Recurrent Unit (GRU) to effectively detect various types of cyber threats using tabular-based image data. To transform time series features into 2D texture images, Gramian Angular Fields (GAFs) are utilized. These images are then stacked to form an N-channel image, which is fed into the CNN-GRU architecture for sequence analysis and identification of potential threats. The provide solution GAF-CNN-GRU achieved an accuracy of 98.6% on the Cranfield Embedded Systems Attack Dataset. We further achieved Precision, Recall and F1-scores of 97.84%, 91% and 94.3%. To evaluate model robustness we further tested this approach, using a benchmark random selection of input features, on the Canadian Institute for Cyber-Security (CIC) 2019 Distributed Denial-of-service attack (DDoS) Dataset achieving an Accuracy of 89.08%. Following feature optimisation our approach was able to achieve an accuracy of 98.36% with Precision, Recall and F1 scores of 93.09%, 95.45% and 94.56% respectively.Item Open Access A3 thinking approach to support knowledge-driven design(Springer, 2013-03-01) Mohd Saad, Norhairin; Al-Ashaab, Ahmed; Maksimovic, Maksim; Zhu, L.; Shehab, Essam; Ewers, P.; Kassam, A.Problem solving is a crucial skill in product development. Any lack of effective decision making at an early design stage will affect productivity and increase costs and the lead time for the other stages of the product development life cycle. This could be improved by the use of a simple and informative approach which allows the designers and engineers to make decisions in product design by providing useful knowledge. This paper presents a novel A3 thinking approach to problem solving in product design, and provides a new A3 template which is structured from a combination of customised elements (e.g. the 8 Disciplines approach) and reflection practice. This approach was validated using a case study in the Electromagnetic Compatibility (EMC) design issue for an automotive electrical sub-assembly product. The main advantage of the developed approach is to create and capture the useful knowledge in a simple manner. Moreover, the approach provides a reflection section allowing the designers to turn their experience of design problem solving into proper learning and to represent their understanding of the design solution. These will be systematically structured (e.g. as a design checklist) to be circulated and shared as a reference for future design projects. Thus, the recurrence of similar design problems will be prevented and will aid the designers in adopting the expected EMC test results.Item Open Access Abating CO2 and non-CO2 emissions with hydrogen propulsion(Cambridge University Press (CUP), 2024-04-02) Mourouzidis, Christos; Singh, G.; Sun, X.; Huete, Jon; Nalianda, Devaiah; Nikolaidis, Theoklis; Sethi, Vishal; Rolt, Andrew Martin; Goodger, E.; Pilidis, PericlesThis contribution focuses on the abatement with hydrogen of CO2 and non-CO2 emissions. It is agenda-setting in two respects. Firstly, it challenges the globally accepted hydrocarbon sustainable aviation fuel (SAF) pathway to sustainability and recommends that our industry accelerates along the hydrogen pathway to ‘green’ aviation. Secondly, it reports a philosophical and analytical investigation of appropriate accuracy on abatement strategies for nitrogen oxides and contrails of large hydrogen airliners. For the second contribution, a comparison is made of nitrogen oxide emissions and contrail avoidance options of two hydrogen airliners and a conventional airliner of similar passenger capacity. The hydrogen aircraft are representative of the first and second innovation waves where the main difference is the weight of the hydrogen tanks. Flights of 1000, 2000, 4000 and 8000 nautical miles are explored. Cranfield’s state of the art simulators for propulsion system integration and gas turbine performance (Orion and Turbomatch) were used for this. There are two primary contributions to knowledge. The first is a new set of questions to be asked of SAF and hydrogen decarbonising features. The second is the quantification of the benefits from hydrogen on non-CO2 emissions. For the second generation of long-range hydrogen-fuelled aircraft having gas turbine propulsion, lighter tanks (needing less thrust and lower gas temperatures) are anticipated to reduce NOx emissions by over 20%; in the case of contrails, the preliminary findings indicate that regardless of the fuel, contrails could largely be avoided with fuel-burn penalties of a few per cent. Mitigating action is only needed for a small fraction of flights. For conventional aircraft this penalty results in more CO2, while for hydrogen aircraft the additional emission is water vapour. The conclusion is that our research community should continue to consider hydrogen as the key ‘greening’ option for aviation, notwithstanding the very significant costs of transition.Item Open Access Abnormal grain growth in ultrafine grained Ni under high-cycle loading(Elsevier, 2021-11-02) Barrios, Alejandro; Zhang, Yin; Maeder, Xavier; Castelluccio, Gustavo M.; Pierron, Olivier; Zhu, TingAbnormal grain growth can occur in polycrystalline materials with only a fraction of grains growing drastically to consume other grains. Here we report abnormal grain growth in ultrafine grained metal in a rarely explored high-cycle loading regime at ambient temperature. Abnormal grain growth is observed in electroplated Ni microbeams with average initial grain sizes less than 640 nm under a large number of loading cycles (up to 109) with low strain amplitudes (< 0.3%). Such abnormal grain growth occurs predominantly in the family of grains whose <100> orientation is along the tensile/compressive loading direction. Micromechanics analysis suggests that the elastic anisotropy of grains dictates the thermodynamic driving force of abnormal grain growth, such that the lowest strain energy density of the <100> oriented grain family dominates grain growth. This work unveils a unique type of abnormal grain growth that may be harnessed to tailor grain microstructures in materials.Item Open Access Abrupt fault detection and isolation for gas turbine components based on a 1D convolutional neural network using time series data(AIAA, 2020-08-17) Zhao, Junjie; Li, YiguangThe FDI step identifies the presence of a fault, its level, type, and possible location. Gas turbine gas-path fault detection and isolation can improve the availability and economy of gas turbine components. Data-driven FDI methods are studied in this paper. Some notable gas turbine FDI challenges include: insensitivity to operating conditions, robust separation of faults, noisy sensor readings and missing data, reliable fault detection in time-varying conditions, and the influence of performance gradual deterioration. For conventional ML methods, the problem with handling time series data is its volume and the associated computational complexity; therefore, the available information must be appropriately compressed via the transformation of high-dimensional data into a low-dimensional feature space with minimal loss of class separability. In order to improve the detection and isolation sensitivity, this paper develops a method for FDI based on CNNs. Work in this paper includes: (1) Defining the problem and assembling a dataset. (2) Preparing data for training, validation and test: data generation, feature engineering, data pre-processing, data formatting. (3) Building up the model. (4) Training and validating the model (evaluation protocol). (5) Optimizing: a. deciding the model size. b. regularizing the model by getting more training data, reducing the capacity of the network, adding weight regularization or adding dropout. c. tuning hyperparameters. (6) Evaluation.Item Open Access Absolute angle measurement using dual-wavelength laser speckle: theory and method(Elsevier, 2023-11-30) Gibson, Sam J.; Charrett, Thomas O. H.; Tatam, Ralph P.This paper presents a method utilising the speckle pattern formed by dual-wavelength illumination for the measurement of the two out-of-plane surface angles with respect to the sensor frame. Theoretical expressions are derived relating the observed speckle shift between patterns formed by two wavelengths for tilted surfaces with both on-axis and off-axis detector positions. These expressions are verified experimentally, showing RMS errors of between 0.5–1.0 . Finally, an on-axis implementation of the concept is presented using dual-wavelength illumination generated from two modes of a standard FP diode laser. Simplified expressions for the calculation of surface angles from measured speckle shift using this arrangement are presented, given in terms of three sensor constants; the responsivity or sensitivity of the sensor, C, and the zero surface tilt speckle shifts, Ax0 and Ay0. Experimental results using this sensor for a range of surface tilts between 0.0° and 7.5° showed an RMS error of 0.10° in θx and 0.19° in θy.Item Open Access Accelerated microwave curing of fibre-reinforced thermoset polymer composites for structural applications: A review of scientific challenges(Elsevier, 2018-09-12) Mgbemena, Chinedum Ogonna; Li, Danning; Lin, Meng-Fang; Liddel, Paul Daniel; Katnam, Kali Babu; Kumar, Vijay Thakur; Nezhad, Hamed YazdaniAccelerated curing of high performance fibre-reinforced polymer (FRP) composites via microwave heating or radiation, which can significantly reduce cure time and increase energy efficiency, has several major challenges (e.g. uneven depth of radiation penetration, reinforcing fibre shielding, uneven curing, introduction of hot spots etc). This article reviews the current scientific challenges with microwave curing of FRP composites considering the underlying physics of microwave radiation absorption in thermoset-matrix composites. The fundamental principles behind efficient accelerated curing of composites using microwave radiation heating are reviewed and presented, especially focusing on the relation between penetration depth, microwave frequency, dielectric properties and cure degree. Based on this review, major factors influencing microwave curing of thermoset-matrix composites are identified, and recommendations for efficient cure cycle design are provided.Item Open Access An accelerometer based-feedback technique for improving dynamic performance of a machine tool(European Society for Precision Engineering and Nanotechnology, 2016-06-30) Abir, Jonathan; Morantz, Paul; Longo, Stefano; Shore, PaulA novel concept for improving machine dynamic performance was developed and realised, a virtual metrology frame, for a small size CNC machine with flexible frame. Its implementation in a simplified linear motion system shows a reduction in the magnitude of the first resonance in the plant frequency response function by 12 dB. Realising the concept required developing a real -time accelerometer-based measurement technique. It shows a low sensor noise σ=30 nm with optimal phase delay of <70 μs.