Technical Reports - Engineering


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  • ItemPublished versionOpen Access
  • ItemPublished versionOpen Access
  • ItemPublished versionOpen Access
    Higher Capacity Vehicles (HCVs) Summary Report
    (2020-03) Piecyk, Maja; Allen, Julian
  • ItemOpen Access
    Proceedings of the 11th Cambridge Workshop on Universal Access and Assistive Technology, held in Cambridge, 27-29 March 2023
    (University of Cambridge, Department of Engineering, 2023-03-01) CWUAAT; Goodmean-Deane, J.; Dong, H.; Heylighen, A.; Lazar, J.; Clarkson, P. J.
  • ItemPublished versionOpen Access
    Low Carbon Concrete Technologies (LCCT): Understanding and Implementation, EPSRC IAA Final report
    (University of Cambridge Department of Engineering, 2022-03-01) Drewniok, Michal; Cullen, Jonathan; Hibbert, Aurelia; Drewniok, Michal [0000-0003-1491-3401]
  • ItemPublished versionOpen Access
    Resource Use in Poland in 2019: Challenges and Opportunities
    (University of Cambridge Department of Engineering, 2021-10-10) Drewniok, Michal; Cullen, Jonathan; Cervantes Barron, Karla; Azevedo, Jose; Drewniok, Michal [0000-0003-1491-3401]
  • ItemPublished versionOpen Access
    Digital Manufacturing on a Shoestring - Low cost digital solutions for SMEs
    (2019-09-16) McFarlane, Duncan; De Silva, Lavindra; Hawkridge, Gregory; Parlikad, Ajith; Perez Hernandez, Marco; Schönfuß, Benjamin; Terrazas Angulo, German; Thorne, Alan; Tlegenov, Yedige; Ratchev, Svetan; Arrand, Helena; Chaplin, Jack; Martinez Arellano, Giovanna; McNally, Michael; McFarlane, Duncan [0000-0002-1558-7823]; Hawkridge, Gregory [0000-0002-7539-1697]; Terrazas Angulo, German [0000-0001-8476-3758]
    This paper introduces the Digital Manufacturing on a Shoestring programme as a whole and demonstrates the way in which it addresses the need for low cost digital solutions for SME Manufacturers. It discusses challenges associated with integrating low cost technologies into industrial solutions and the style of IT architectures best suited for integrating these solutions into industrial environments.
  • ItemPublished versionOpen Access
    Digital Manufacturing on a Shoestring - Low-Cost Digital Solutions for Manufacturing SMEs: A Catalogue of Digital Solution Areas
    (2021-11-18) McFarlane, Duncan; Schönfuß, Benjamin; Hawkridge, Gregory; Salter, Elizabeth; Athanassopoulou, Nicky; De Silva, Lavindra; McFarlane, Duncan [0000-0002-1558-7823]; Hawkridge, Gregory [0000-0002-7539-1697]
    The aim of this paper is to present a catalogue comprising a set of digital solution areas associated with operational challenges that are relevant to a majority of manufacturing small to medium sized enterprises (SMEs). The working catalogue has been developed in consultation with over 100 manufacturing SMEs. The working catalogue describes 59 solution areas identified to the end of 2020. Out of all participants in the study, 86% ranked one of the top 5 items in the catalogue as a key priority for their business. These findings can help increase accessibility to digitalisation for manufacturing SMEs.
  • ItemPublished versionOpen Access
    Relationships between building structural parameters and embodied carbon Part 1: Early-stage design decisions
    (University of Cambridge Department of Engineering, 2021-09-21) Drewniok, Michal; Drewniok, Michal [0000-0003-1491-3401]
    The purpose of the placement was to assess the relationship between embodied carbon and the various structural requirements of a building design brief. The placement analysed both theoretical and real buildings to produce guidance that clarifies these relationships. The main focus of this placement was to find relationship between structural depth ver. spans, live loads and initial carbon intensity for different structural solutions (floor solutions). This report can be used as a design guidance to communicate relationships and inform future decisions as well as by designers to make informed design decisions and communicate the implications of the brief to clients.
  • ItemOpen Access
    Real image denoising with a locally-adaptive bitonic filter
    (2021-09-08) Treece, Graham; Treece, Graham [0000-0003-0047-6845]
    The bitonic filter is a non-learning-based filter for removing noise from signals, following mathematical morphology (ranking) approaches, relying on a novel presumption in which the signal is postulated to be locally bitonic (having only one minimum or maximum) over some domain of finite extent. It is here developed specifically for image noise so that the domain is locallyadaptive, leading to significant improvements in noise reduction performance at no cost to processing times. The new bitonic filter performs better than the block-matching 3D filter for high levels of additive white Gaussian noise, and over all noise levels for two public data sets containing real image noise. This is despite an additional adjustment to the block-matching filter for real image noise, which leads to significantly better performance than has previously been cited on these data sets. The new bitonic filter has a signal-to-noise ratio only 2.4 dB lower than the best learning-based techniques when they are optimally trained. The performance gap is closed completely when these techniques are trained on data sets not directly related to the benchmark data. This demonstrates what can be achieved with a predictable, explainable, entirely local technique, which makes no assumptions of repeating patterns either within an image or across images, and hence creates residual images which are well behaved even in very high noise. Since the filter does not require training, it can still be used in situations where training is either difficult or inappropriate.
  • ItemOpen Access
    A Model of Driver Steering Control Incorporating Steering Torque Feedback and State Estimation
    (Cambridge University Engineering Department, 2020-11-05) Niu, Tenghao; Cole, David; Cole, David [0000-0003-3162-701X]
    Steering feel, or steering torque feedback plays an important role in the steering control task. In this report, a new driver steering control model incorporating steering torque feedback state estimation is proposed. The hypothesis is that the human driver obtains an internal mental model of the steering and vehicle dynamics, which is used in sensory perception, cognitive control, and neuromuscular action. The new model could be used to predict a driver’s responses when steering a vehicle with steering torque feedback.
  • ItemOpen Access
    Practicable assessment of cochlear size and shape from clinical CT images.
    (Springer Science and Business Media LLC, 2021-02-10) Gee, Andrew H; Zhao, Yufeng; Treece, Graham M; Bance, Manohar L; Treece, Graham [0000-0003-0047-6845]
    There is considerable interpersonal variation in the size and shape of the human cochlea, with evident consequences for cochlear implantation. The ability to characterize a specific cochlea, from preoperative computed tomography (CT) images, would allow the clinician to personalize the choice of electrode, surgical approach and postoperative programming. In this study, we present a fast, practicable and freely available method for estimating cochlear size and shape from clinical CT. The approach taken is to fit a template surface to the CT data, using either a statistical shape model or a locally affine deformation (LAD). After fitting, we measure cochlear size, duct length and a novel measure of basal turn non-planarity, which we suggest might correlate with the risk of insertion trauma. Gold-standard measurements from a convenience sample of 18 micro-CT scans are compared with the same quantities estimated from low-resolution, noisy, pseudo-clinical data synthesized from the same micro-CT scans. The best results were obtained using the LAD method, with an expected error of 8-17% of the gold-standard sample range for non-planarity, cochlear size and duct length.
  • ItemOpen Access
    Energy Cost Metric. Energy Design Guide for the Civil Engineering Building in West Cambridge. Part 1: Early stage design decisions
    (Department of Engineering, University of Cambridge, 2020-04-30) MacKay, David; Bock, Maximilian; Cebon, David; Doig, Katie; Drewniok, Michal; Cullen, Jonathan; Gustafsson, Joel; Guthrie, Peter; Hibbert, Aurelia; Smith, Simon; Swallow, Peter; Symons, Katie; Tzokova, Petia; Williams, Brian; Cebon, David [0000-0003-2828-6445]; Drewniok, Michal [0000-0003-1491-3401]; Cullen, Jonathan [0000-0003-4347-5025]; Guthrie, Peter [0000-0002-9523-3733]; Tzokova, Petia [0000-0001-5044-4687]
    The Energy Cost Metric (ECM) is anticipated to provide a novel and meaningful approach to designers to achieve very-low energy designs at early stages of the design project, without undue cost. It also serves as a common method and language between beneficiaries, project managers, architects, engineers, contractors and quantity surveys, where matters relating to capital cost, sustainability and energy use can be debated in an inclusive and holistic manner. In this report, the ECM used to design Civil Engineering Building (CEB) was explained and then tested in practice with outside partners on the CEB development project. This report includes the following design stages: the Brief to Design, the Concept Design and early Developed Design (Stages 1-3 according to RIBA Plan of Work 2013) and consists of 5 main chapters: Meeting Sustainability Requirements; Energy Brief for Civil Engineering Building; Energy Cost Metric; Application of Metric; and Discussion and Conclusion.
  • ItemAccepted versionOpen Access
    Effect of swirl on the interaction between laterally placed tidal turbines using actuatordisc based numerical simulations
    (Department of Engineering, University of Cambridge, 2020-05-13) Young, Anna; Ochoa, Rafa Baptista; Gupta, Vikrant; Young, Anna [0000-0002-3517-5850]
    Much of the future potential for tidal energy lies in tidal channels, where turbines can be arranged in an array in such a way as to exploit the effects of channel blockage and thus increase performance. One such strategy employed by researchers has been to have an array of turbines which only partially blocks the channel width. Previous work, employing mass and momentum conservation and considering the turbines as simple actuator disks, has shown that the local arrangement of the turbines can be altered in a way that optimises the power output of the whole array. However, real turbines also impart swirl to the flow. When this swirl imposed on the flow by the turbines is taken into account by modelling the turbines with Blade ElementMomentum Theory (BEMT) discs, further interaction effects become apparent. These effects depend on the proximity of the turbines to one another and can have a significant impact on the optimal arrangement of the devices in a given channel. This report demonstrates the key effects by comparing sets of actuator disc simulations with and without BEMT, and makes the case for taking swirl effects into account when designing tidal arrays computationally. The other benefit of using BEMT discs is that they rely only on known, physical characteristics of the turbines (i.e. lift and drag performance curves) as opposed to estimated quantities (i.e. the momentumextraction coefficient). This means that real turbines can be simulated with more accuracy. It will be argued in this paper that these twin advantages of increased realism in both the flow field and the turbine outweigh the negligible increase in computing power required to undertake BEMT simulations and so these simulations should be theminimum standard for tidal array designs.
  • ItemPublished versionOpen Access
    FE modelling of small-scale hot deformation testing
    (Cambridge University Engineering Department, 2019-12-13) Jedrasiak, Patryk; Shercliff, Hugh; Shercliff, Hugh [0000-0001-5950-8026]
    This report presents a finite element model of small-scale hot compression testing, using a dilatometer in loading mode. The main goal is to correct the true stress-strain hot constitutive response as a function of temperature and strain-rate, accounting for friction between the platens and workpiece, and the temperature gradient along the sample. The model also provides quantitative prediction of the spatial and temporal variation in strain-rate and strain throughout the sample, which is needed to correlate the local deformation conditions with the microstructure/texture evolution. The study is based on a detailed series of 144 hot compression tests of a zirconium alloy (Zr-2.5Nb), at strain-rates ranging from 10-2.5 to 10s-1, and temperatures between 650°C to 850°C, with duplicate tests at all nominal test conditions. The Zr alloy is an important wrought material in its own right, in the context of the nuclear industry, but also serves as an analogue for other high temperature alloys (notably titanium) which show a dual - phase microstructure in a comparable temperature range. The finite element model of the dilatometer test demonstrated that deformation conditions in the sample were substantially non-uniform, compared to the nominal temperature and strain-rate. The heating and cooling capabilities of the dilatometer were able to maintain reasonably isothermal conditions at the centre of the sample at moderate strain-rates, but not at rates of 1s-1 or above; but in all cases the temperature gradient and friction led to inhomogeneous deformation and barrelling. To account for these factors, a novel method is presented for correcting the true stress-strain (i.e. from the notional response allowing only for the idealised change in sample length and area), to give a true constitutive response over the full range of temperatures, strain-rates and strain. The analysis in this report includes a number of alternative approaches to capturing the material constitutive data in equations or look-up tables, and also detailed sensitivity analysis on the FE-predicted spatial histories of deformation, as a function of the assumed material model and friction coefficient, for different test temperatures, temperature gradients and strain-rates. The FE-corrected constitutive data have been applied for a number of applications, for example, the generation of “processing maps” for Zr-2.5Nb, demonstrating the importance of allowing for inhomogeneity and meaningful statistical fitting of the data; this work is presented in more detail elsewhere [1].
  • ItemAccepted versionOpen Access
    Calibration of tactile pressure sensing mats for static geotechnical centrifuge applications
    (2019-12-30) Chan, Deryck; Madabhushi, Santana; Deng, Chuhan; Haigh, Stuart; Chan, Deryck [0000-0003-4485-8853]; Madabhushi, Gopal [0000-0003-4031-8761]; Haigh, Stuart [0000-0003-3782-0099]
    The use of tactile pressure sensing mats has been gaining popularity among geotechnical centrifuge modellers. Tactile sensing systems such as Tekscan allow experimenters to obtain profiles of soil-structure contact pressures and visualise the results. This report builds upon previous work on the calibration of such pressure mats and describes how they were used to measure slab-soil and wall-soil contact pressures on basements models subject to heave movements in clay, for the benefit of future researchers who want to use tactile pressure mats for static geotechnical centrifuge applications. Each Tekscan sheet should be waterproofed by lamination and then calibrated. Known loads were applied onto Tekscan sheets using the Enerpac hydraulic frame in Schofield Centre. This produced individual calibration curves for each sensel. In contrast to previous work which fit a linear calibration relationship to measure cyclic load changes, large changes in pressure were expected in the basement heave centrifuge tests, with pressures sometimes dropping to near-zero values. Therefore, a quadratic fit with a forced zero intercept was applied to each sensel to capture the non-linearity of sensitivity. The dead weight of the basement slab and heavy fluid during spin-up and in-flight reconsolidation provided an independent check of the calibration factors. This check also generates a calibration adjustment factor which may account for the influence of centrifuge gravity on the tactile sensors’ sensitivity. The data was processed using Matlab with filtering in both time (averaging over 10 frames, typically) and space (taking special averages, typically over a 3×3 grid), and then presented as graphs and heat maps.
  • ItemOpen Access
    A critique of the statistical protocol in ISO 20072 for aerosol drug delivery device design verification.
    (University of Cambridge, 2016-10-08) MacKay, David; Christescu, MS; Tirlea, MA
    ISO 20072 is an international standard detailing the methods and testing protocols required to ensure the quality of aerosol drug delivery devices (ADDDs), for use in humans [1]. Our paper examined the pitfalls and errors in this standard, and the difficulties in its application to ADDD-producing factories. We find that the likelihood of many imperfect factories which satisfy the requirements listed in the standard actually passing the prescribed testing is minuscule. We suggest other testing protocols, which achieve the stated goals of the standard. In the specific example we consider, they also reduce the workload by around 25-fold compared with the methods specified in ISO 20072, as well as giving crucial additional advantages.
  • ItemOpen Access
    From modularity to emergence: a primer on the design and science of complex systems
    (Department of Engineering, University of Cambridge, 2016-09-23) Chen, Chih-Chun; Crilly, Nathan; Chen, Chih-Chun [0000-0003-0961-2612]; Crilly, Nathan [0000-0003-0784-6802]
    Electrical networks, flocking birds, transportation hubs, weather patterns, commercial organisations, swarming robots... Increasingly, many of the systems that we want to engineer or understand are said to be ‘complex’. These systems are often considered to be intractable because of their unpredictability, non-linearity, interconnectivity, heterarchy and ‘emergence’. Such attributes are often framed as a problem, but can also be exploited to encourage systems to efficiently exhibit intelligent, robust, self-organising behaviours. But what does it mean to describe systems as complex? How do these complex systems differ from the more easily understood ‘modular’ systems that we are familiar with? What are the underlying similarities between different systems, whether modular or complex? Answering these questions is a first step in approaching the design and science of complexity. However, to do so, it is necessary to look beyond the specifics of any particular system or field of study. We need to consider the fundamental nature of systems, looking for a common way to view ostensibly different phenomena. This primer introduces a domain-neutral framework and diagrammatic scheme for characterising the ways in which systems are modular or complex. Rather than seeing modularity and complexity as inherent attributes of systems, we instead see them as ways in which those systems are characterised by those who are interested in them. The framework is not tied to any established mode of representation (e.g. networks, equations, formal modelling languages) nor to any domain-specific terminology (e.g. ‘vertex’, ‘eigenvector’, ‘entropy’). Instead, it consists of basic system constructs and three fundamental attributes of modular system architecture, namely structural encapsulation, function-structure mapping and interfacing. These constructs and attributes encourage more precise descriptions of different aspects of complexity (e.g. emergence, self-organisation, heterarchy). This allows researchers and practitioners from different disciplines to share methods, theories and findings related to the design and study of different systems, even when those systems appear superficially dissimilar.
  • ItemOpen Access
    Refinement of clinical X-ray computed tomography (CT) scans containing metal implants
    (2016-04) Treece, Graham
    X-ray Computed Tomography (CT) data contains artefacts from many sources and these are sufficiently prominent to affect diagnostic utility when metal is present in the scans. Several techniques have been proposed to reduce these artefacts, the most successful involving the removal and filling in of any sinogram data which has been affected by metal. Most such techniques are prone to introducing new artefacts into the CT data or may take a long time to correct the data. In this paper, a new technique is proposed which is fast, yet can effectively remove most artefacts without introducing significant new ones. This is thoroughly tested against both published and commercial alternatives, quantitatively on phantom data, and qualitatively on a selection of clinical scans, mostly of the hip. The phantom data is from two recently published studies, enabling direct comparison with the technique presented here. The results show an improvement in reducing artefacts on phantom data, in most cases significant at p < 0:001, with similar qualitative improvements on clinical data, particularly for bony features close to metal implants.
  • ItemOpen Access
    The bitonic filter: linear filtering in an edge-preserving morphological framework.
    (University of Cambridge Department of Engineering, 2015-12-15) Treece, Graham
    A new filter is presented which has better edge and detail preserving properties than a median, noise reduction capability very similar to a Gaussian, and is applicable to many signal and noise types. It is built on a definition of signal as bitonic, i.e. containing only one local maxima or minima within the filter range. This definition is based on data ranking rather than value, hence the bitonic filter is non-linear, comprising a combination of morphological and linear operators. It has no data-level-sensitive parameters and can locally adapt to the signal and noise levels in an image, precisely preserving both smooth and discontinuous signals of any level when there is no noise, but also reducing noise in other areas without creating additional artefactual noise. Both the basis and the performance of the filter are examined in detail, and it is shown to be a significant improvement on the Gaussian and median. It is also compared over various noisy images to the image-guided filter, anisotropic diffusion and the non-local means filter. Whilst the bitonic filter does not outperform non-local means, nor always anisotropic diffusion, it does give good results in all circumstances, with distinct characteristics that make it appropriate particularly for signals or images with varying noise, or features at varying levels. The bitonic has very few parameters, does not require optimisation nor prior knowledge of noise levels, does not have any problems with stability, and is reasonably fast to implement. Despite it’s non-linearity, it hence represents a very practical operation with general applicability. ***A derivative of this work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.***