Staff publications (CDS)

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Open Access
2016 British Crystallographic Association (BCA) Spring Meeting, April 4–7, 2016
(Cambridge University Press, 2016-12) Rendle, D
Review of the 2016 British Crystallographic Association (BCA) Spring Meeting, April 4–7, 2016
Open Access
3D automatic target recognition for future LIDAR missiles
(IEEE, 2017-01-10) Kechagias-Stamatis, Odysseas; Aouf, Nabil; Richardson, Mark A.
We present a real-time three-dimensional automatic target recognition approach appropriate for future light detection and ranging-based missiles. Our technique extends the speeded-up robust features method into the third dimension by solving multiple two-dimensional problems and performs template matching based on the extreme case of a single pose per target. Evaluation on military targets shows higher recognition rates under various transformations and perturbations at lower processing time compared to state-of-the-art approaches.
Open Access
3D Lagrangian particle tracking of a subsonic jet using multi-pulse Shake-The-Box
(Elsevier, 2021-01-19) Manovski, Peter; Novara, Matteo; Karthik, Nagendra; Mohan, Depuru; Geisler, Reinhard; Schanz, Daniel; Agocs, Janos; Godbersen, Philipp; Schröder, Andreas
Three-dimensional (3D) Lagrangian Particle Tracking (LPT) was performed on a subsonic jet flow at Mach 0.506 and 0.845 generated by a round nozzle with diameter-based Reynolds numbers of 1.7×105 and 3.1×105, respectively. The Multi-Pulse Shake-The-Box (MP-STB) technique was employed to reconstruct particle tracks along the four-pulse sequences, which were obtained by using orthogonally polarised light to separate the pulses on camera images. The MP-STB method applied here has a number of differences compared to previous publications, in particular, a new adaptive search radii approach and an iterative strategy and particle track validation criteria that have been customised for high subsonic/transonic flows. A description of this methodology is given followed by presentation of the instantaneous 3D flow velocity and material acceleration particle tracks. By ensemble-averaging the scattered instantaneous measurements extracted from individual particle tracks into small volumetric bins, highly resolved statistical quantities were obtained. The performance of MP-STB was assessed by comparing velocity profiles with published particle image velocimetry (PIV) data-sets. MP-STB was better able to resolve the steep velocity gradients, in particular the thin jet shear layer near the nozzle exit. At this location the MP-STB results also yielded higher turbulence intensities compared with the reported studies for similar flow conditions. The MP-STB acceleration flow statistics were compared for the two Mach numbers, and for the Mach 0.506 case, higher levels of normalised acceleration and fluctuations were found. The position accuracy of the 3D imaging system was quantified and it was found that the use of two different states of polarisation had a direct impact on the accuracy and the amount successfully tracked particles. Further assessment of the particle imaging quality of each camera revealed a significant disparity between cameras. This was attributed to the particle light scattering intensity variations, which were highly dependent on the particle size, camera angles and different states of polarised light. Despite these challenges, an average of40,000 individual particle tracks could be reconstructed from a typical particle image density of 0.02 particles per px (and an active sensor area of 1800×2200 px2). Furthermore, the accuracy of the measurement was shown to be relatively high, with respect to PIV.
Open Access
3D printing, the future of cost effective biomechanical testing
(SAFE, 2017-04-06) Franceskides, C.; Arnold, Emily; Horsfall, Ian; Clasper, J.; Tozzi, G.; Zioupos, Peter
Open Access
A 3D-collaborative wireless network: towards resilient communication for rescuing flood victims
(IEEE, 2018-04-02) Rahman, Md. Arafatur; Hasan, Md. Munirul; Asyhari, A. Taufiq; Alam Bhuiyan, Md. Zakirul
Every year, floods result in huge damage and devastation both to lives and properties all over the world. Much of this devastation and its prolonged effects result from a lack of collaboration among the rescue agents as a consequence of the lack of reliable and resilient communication platform in the disrupted and damaged environments. In order to counteract this issue, this paper aims to propose a three-dimensional (3D)- collaborative wireless network utilizing air, water and ground based communication infrastructures to support rescue missions in flood-affected areas. Through simulated Search and Rescue(SAR) activities, the effectiveness of the proposed network model is validated and its superiority over the traditional SAR is demonstrated, particularly in the harsh flood environments. The model of the 3D-Collaborative wireless network is expected to significantly assist the rescuing teams in accomplishing their task more effectively in the corresponding disaster areas.
Open Access
3D-printed coded apertures for x-ray backscatter radiography
(SPIE, 2017-09-07) Munoz, Andre Arelius Marcus; Vella, Anna; Healy, M. J. F.; Lane, David W.; Jupp, Ian; Lockley, D.
Many different mask patterns can be used for X-ray backscatter imaging using coded apertures, which can find application in the medical, industrial and security sectors. While some of these patterns may be considered to have a self-supporting structure, this is not the case for some of the most frequently used patterns such as uniformly redundant arrays or any pattern with a high open fraction. This makes mask construction difficult and usually requires a compromise in its design by drilling holes or adopting a no two holes touching version of the original pattern. In this study, this compromise was avoided by 3D printing a support structure that was then filled with a radiopaque material to create the completed mask. The coded masks were manufactured using two different methods, hot cast and cold cast. Hot casting involved casting a bismuth alloy at 80°C into the 3D printed acrylonitrile butadiene styrene mould which produced an absorber with density of 8.6 g cm-3. Cold casting was undertaken at room temperature, when a tungsten/epoxy composite was cast into a 3D printed polylactic acid mould. The cold cast procedure offered a greater density of around 9.6 to 10 g cm-3 and consequently greater X-ray attenuation. It was also found to be much easier to manufacture and more cost effective. A critical review of the manufacturing procedure is presented along with some typical images. In both cases the 3D printing process allowed square apertures to be created avoiding their approximation by circular holes when conventional drilling is used.
Open Access
5 year public health impacts of an urban greenway, Belfast, Northern Ireland: Causal Loop Diagram (Abstract no diagram)
(Oxford University Press, 2023-10-24) Hunter, R.; Garcia, L.; Clewley, Natalie; Hafezi, Mehdi; Hilton, Jeremy
Background The development of large scale urban green space infrastructure, such as a new urban greenway, provokes a cascade of changes abating a series of public health impacts, in the realms of: health, society, economy and the environment. The relationships between these factors sustain reciprocal and dynamic influence with potential to generate a virtuous cycle. However, such long-term impacts and their inter-relationships are poorly understood. Methods We aimed to co-develop a shared understanding of the public health impacts of the Connswater Community Greenway with multi-sectoral stakeholders 5 years post-implementation. Objectives were to (a) build shared understanding of the complex system influencing the public health impact of the Connswater Community Greenway, and (b) identify and explore priorities, opportunities, and actions to improve future impacts. We undertook Group Model Building workshops with people representing relevant stakeholders involved in the development and/or maintenance of the Connswater Community Greenway, and local residents living on or along the greenway. Results 23 participants were involved in the workshop included local governmental agencies, local residents, advocacy groups, private sector, and researchers. Stakeholders produced a systems map detailing the public health impacts of the Connswater Community Greenway 5 years post-implementation. Key impacts included increased in mental wellbeing, sense of community pride, increased biodiversity, increased economic investment in the local area. Participants identified a range of priority actions that, in their view, could impact and help reshape the system and influence the future impacts of the greenway. Conclusions The CLD was reflective of the various stakeholders’ experience, knowledge, perceptions, and views about the factors, and the inter-relationships between these factors, of the public health impact of the Connswater Community Greenway at 5 years post-implementation. Key messages • Systems thinking approaches can help identify the public health impacts and plausible causal pathways of green space interventions. • 5 year impacts of an urban greenway included improvements in the realms of health, wellbeing, the environment, the economy and society.
Open Access
6 Shipwreck archaeology in the past 10 years
(Cambridge University Press (CUP), 2023-12-08) Briggs, Lisa; Campbell, Peter B.
This paper reviews the trends, topics, and research directions in shipwreck archaeology over the past decade. As archaeology increasingly embraces advances in technological methods that can aid our research, the so-called ‘digital turn’, it behoves maritime archaeologists, and archaeologists more broadly, to consider how collaborative utilization of specialized fields including biomolecular archaeology, geophysics, and contemporary philosophy have spurred on a rapid modernization of our field in recent times. Archaeological research, both terrestrial and underwater, has long been a collaborative discipline. However, we argue here that difficulties in working underwater have encouraged maritime and underwater archaeologists to embrace technological developments at a rapid pace. An explicit theoretical framework and the incorporation of contemporary philosophy in the field of underwater archaeology was, until recently, largely lacking in the discipline’s discourse. The incorporation and advancement of adjacent disciplines within the field of underwater archaeology mark the most relevant changes within the shifting tides of shipwreck research.
Open Access
A two-stage classification method for improved positioning using low-cost inertial sensors
(IEEE, 2024-08-08) Maton, Dariusz; Economou, John; Galvao Wall, David; Khan, Irfan; Cooper, Robert; Ward, David; Trythall, Simon
The two-stage subtractive clustering Takagi-Sugeno (2SC-TS) method is proposed which completely replaces the established method of inertial navigation with classification models. The classifiers are designed by the subtractive clustering algorithm, an unsupervised learning method. The accuracy of the trajectories is compared against three competitive data-driven methods on three independent experimental datasets. The results show how 2SC-TS generates trajectories with approximately 20% lower positional error compared with the single-stage version (SC-TS), and halves the error produced by competitive deep learning methods. The proposed method may help improve the positioning of people and robots carrying low-cost inertial sensors.
Open Access
Accuracy of computed radiography in osteometry: a comparison of digital imaging techniques and the effect of magnification
(Elsevier, 2019-10-24) Carew, Rachael M.; Viner, Mark D.; Conlogue, Gerald J.; Márquez-Grant, Nicholas; Beckett, Sophie
Introduction Osteometric data may be obtained using digital imaging techniques, such as post-mortem computed tomography (PMCT) and digital radiography, non-invasively and without ethical objection. Osteometric data from PMCT is known to be as accurate as taking direct measurements. Digital radiography is more accessible and affordable than PMCT but is limited due to the magnification of its subjects. Objectives To investigate the viability of implementing digital radiographic techniques for measurement of long bones, and to establish whether magnification can be accurately corrected for. Materials and Methods Twenty hind pig (Sus scrofa) legs were imaged using computed radiography (CR) and PMCT, and osteometric data obtained from the digital images and 3D CT volume reconstructions. Direct measurements were taken following maceration. A calibration object was imaged using CR, to provide magnification correction factors. Results Accuracy was determined by mean absolute error (AE), giving values of 3.3 ± 2.5 mm for PMCT (MPR), 2.4 ± 1.3 mm for PMCT (3D), 11.1 ± 7.4 mm for CR (PA), and 18.3 ± 14.5 mm for CR (LAT). PMCT data was more accurate than CR data. Through applying correction for magnification, CR data became closer to the direct measurement data, and stature estimation was substantially altered. Conclusion Magnification in computed radiography affects osteometric data and resulting stature estimations. Applying correction factors may be a viable option for improving accuracy. For digital radiography to be used reliably in forensic anthropology, further empirical research is needed to validate a magnification correction method.
Open Access
ACD-G: Enhancing autonomous cyber defense agent generalization through graph embedded network representation
(International Conference on Machine Learning, 2022-07-23) Collyer, Josh; Andrew, Alex; Hodges, Duncan
The adoption of autonomous cyber defense agents within real-world contexts requires them to be able to cope with differences between their training and target environments, bridging the simulation to real gap to provide robust, generalized defensive responses. Whilst the simulation to real gap has been studied in-depth across domains such as robotics, to date there has been minimal research considering generalizability in the context of cyber defense agents and how differences in observation space could enhance agent generalizability when placed into environments that differ from the training environment. Within this paper, we propose a method of enhancing agent generalizability and performance within unseen environments by integrating a graph embedded network representation into the agent’s observation space. We then compare agent performance with and without a graph embedded network representation based observation space within a series of randomized cyber defense simulations. We find that there is a trade-off between the effectiveness of the graph embedding representation and the complexity of the graph, in terms of node count and number of edges.
Open Access
Acoustic characteristics of a multi-rotor MAV and its noise reduction technology
(Institute of Noise Control Engineering, 2016-08-21) Lu, Zhenbo; Debiasi, Marco; Khoo, Boo Cheong
The present paper is devoted to identify the acoustic characteristic of a multi-rotor MAV, and then explore effective noise reduction technologies for suppressing its high-level noise. It is found that the noise is mainly generated by the high-speed rotating propellers. Surrounding engine rotors with ducts designed to absorb their acoustic emissions is one of the methods typically used for reducing their noise. Thus two duct configurations, with non-perforated internal wall and with micro-perforated internal wall with back cavity, are designed, fabricated using 3D printing, and tested on a multi-rotor MAV. The acoustic performance of these ducts for achieving a quieter flying multi-rotor MAV are analyzed and discussed.
Open Access
AD tools and prospects for optimal AD in CFD flux Jacobian calculations
(2002-01-01T00:00:00Z) Tadjouddine, Mohamed; Forth, Shaun A.; Pryce, John D.
We consider the problem of linearising the short (approximately 100 lines of) code that defines the numerical fluxes of mass, energy and momentum across a-cell face in a finite volume compressible flow calculation. Typical of such formulations is the numerical flux due to Roe, widely used in the numerical approximation of flow fields containing moderate to strong shocks. Roe's flux takes as input 10 variables describing the flow either side of a cell face and returns as output the 5 variables for the numerical flux. We present results concerning the efficiency of derivative calculations for Roe's flux using several currently available AD tools. We also present preliminary work on deriving near optimal differentiated code using the node elimination approach. We show that such techniques, within a source transformation approach, will yield substantial gains for application code such as the Roe flux.
Open Access
An AD-enabled optimization toolbox in LabVIEW(TM)
(2012-07-30T00:00:00Z) Gupta, Abhishek Kr.; Forth, Shaun A.
LabVIEW(TM) is a visual programming environment for data acquisition, instrument control and industrial automation. This article presents LVAD, a graphically programmed implementation of forward mode Automatic Differentiation for LabVIEW. Our results show that the overhead of using overloaded AD in LabVIEW is sufficiently low as to warrant further investigation and that, within the graphical programming environment, AD may be made reasonably user friendly. We further introduce a prototype LabVIEW Optimization Toolbox which utilizes LVAD's derivative information. Our toolbox presently contains two main LabVIEW procedures fzero and fmin for calculating roots and minima respectively of an objective function in a single variable. Two algorithms, Newton and Secant, have been implemented in each case. Our optimization package may be applied to graphically coded objective functions, not the simple string definition of functions used by many of the optimizers of LabVIEW's own optimization package.
Open Access
ADAMS model validation for an all terrain vehicle using test track data
(Sage, 2019-07-15) Kanchwala, Husain; Chatterjee, Anindya
MD ADAMS R is widely used for vehicle suspension modeling. In this paper we present modeling, simulation, and test track evaluation of an all terrain recreational vehicle. Our intention is to study the degree to which simplified ADAMS modeling actually matches human-driven vehicle response. For suspension model validation, a vehicle is generally tested on a four-post test rig and base-excitation is applied at four ground-wheel contacts. However, actual driving experience does not match idealized testing conditions. In this work the vehicle is manually driven on a variety of tracks at different speeds, and the vertical accelerations at four axle locations and four body points are measured. The same are then compared in detail against predictions from ADAMS simulation with vertical base excitation. The contribution of this paper is in identifying those aspects of the simulation results that match experiments well, and identifying possible sources for the observed mismatch, especially under more severe test conditions.
Open Access
Adaptive spatio-temporal CFAR and multiple-hypothesis tracking system
(2009-03-12T16:36:30Z) Hughes, Evan J.; Lewis, M.
This paper describes a self organising spatio-temporal radar CFAR system that uses multiple intelligent software agents to detect and adapt the processing to features in the environment. By combining both temporal and spatial data gathering sufficient samples can be collected to allow both the first and second order moments of the clutter distribution to be approximated for each cell. By gathering higher order statistics to a useful accuracy, more stable thresholds may be produced.
Open Access
Additively manufactured (3DP) thermite structures vs conventionally manufactured equivalents
(IPSUSA Seminars, 2022-07-14) McGee, Christine; Vrcelj, Ranko
Research into additive manufacturing (AM) has been steadily expanding over the past five decades. Where once only polymeric materials could be reliably printed, AM has been adapted to print with a range of materials such as biological, metallic, ceramic and even foodstuffs. The advantages of manufacturing in an additive manner include; a) a layer-by-layer approach allows the creation of architecturally complex structures, b) a reduction in weight, c) lessening of waste and d) the ability to create parts that that are otherwise difficult or too costly to produce. Pyrotechnic materials, including thermites, are used in a wide range of commercial and defence applications. However, hazards present during manufacturing and storage have resulted in major accidents around the world, with subsequent loss of life and in some cases loss of public infrastructure. AM, using a dry powder printing technique means that parts can be manufactured on demand, reducing the need for storage of large volumes of fully formed products or mixes, thus increasing the safety over lifetime of a product. The performance of pyrotechnics materials is dependent on a number of properties, including chemical composition, thermodynamic properties and physical form. In combination with composition, architecture could be utilised to understand and control these properties. A bespoke printer capable of additively manufacturing pyrotechnic materials has been constructed with the aim to explore this research area. In this presentation, we compare the burn rates of AM thermites and compare them to conventionally fabricated compositions and discuss the effects of the print parameters and confinement. We conclude with the results from the burning of AM thermite structures and compare their performance with conventionally prepared equivalent thermite examples.
Open Access
Adjoint Differentiation of a Structural Dynamics Solver.
(2006-12-01T00:00:00Z) Tadjouddine, Mohamed; Forth, Shaun A.; Keane, Andy J.
The design of a satellite boom using passive vibration control by Keane [J. of Sound and Vibration, 1995, 185(3),441-453] has previously been carried out using an energy function of the design geometry aimed at minimising mechanical noise and vibrations. To minimise this cost function, a Genetic Algorithm (GA) was used, enabling modification of the initial geometry for a better design. To improve efficiency, it is proposed to couple the GA with a local search method involving the gradient of the cost function. In this paper, we detail the generation of an adjoint solver by automatic differentiation via ADIFOR. This has resulted in a gradient code that runs in 7.4 times the time of the function evaluation. This should reduce the rather time-consuming process (over 10 CPU days by using parallel processing) of the GA optimiser for this problem.
Open Access
Adopting the bottom-up approach and cluster analysis on North American and European male serial killers
(JSciMed Central, 2017-11-23) Taylor, Sadie; Cahillane, Marie; Workman, Lance
This study explores the application of the FBI’s organised-disorganised classification to North-American and European male serial killers. Adopting the same method as Taylor, Lambeth, Green, Bone and Cahillane’s 2012 study, 52 crime scene criteria were used to categorise the murders committed by 25 male European and 25 male North-American serial killers. Applying content analysis, murders committed were dichotomously coded for the presence or absence of crime scene criteria using numerous secondary sources. Two separate agglomerative hierarchical cluster analyses using Ward’s method as the clustering algorithm formed two clusters for the North-American and two for the European serial killers. There were differences in the crime scene criteria for clusters between North-American and European serial murders. The ‘bottom-up’ approach resulted in clusters from the crime scene criteria demonstrating that there are problems associated with classifying traits as simply organised and disorganised. All clusters comprised of a degree of core organised traits -consistent with Canter, Alison, Alison and Wentink’s (2004) assumption that all serial killings require a degree of organisation. Further examination of frequency of occurrence measures suggests there are subtle but inherent differences between the MO of North American and European serial killers.
Open Access
Adult fly age estimations using cuticular hydrocarbons and Artificial Neural Networks in forensically important Calliphoridae species
(Elsevier, 2017-10-08) Moore, Hannah E.; Butcher, John B.; Day, Charles R.; Drijfhout, Falko P.
Blowflies (Diptera: Calliphoridae) are forensically important as they are known to be one of the first to colonise human remains. The larval stage is typically used to assist a forensic entomologists with adult flies rarely used as they are difficult to age because they remain morphologically similar once they have gone through the initial transformation upon hatching. However, being able to age them is of interest and importance within the field. This study examined the cuticular hydrocarbons (CHC) of Diptera: Calliphoridae species Lucilia sericata, Calliphora vicina and Calliphora vomitoria. The CHSs were extracted from the cuticles of adult flies and analysed using Gas Chromatography-Mass Spectrometry (GC-MS). The chemical profiles were examined for the two Calliphora species at intervals of day 1, 5, 10, 20 and 30 and up to day 10 for L. sericata. The results show significant chemical changes occurring between the immature and mature adult flies over the extraction period examined in this study. With the aid of a Principal Component Analysis (PCA) and Artificial Neural Networks (ANN), samples were seen to cluster, allowing for the age to be established within the aforementioned time frames. The use of ANNs allowed for the automatic classification of novel samples with very good performance. This was a proof of concept study, which developed a method allowing to age post-emergence adults by using their chemical profiles