MRC Laboratory of Molecular Biology
CUED - Cambridge University Engineering DepartmentNot a member yet
45551 research outputs found
Sort by
"reading" cities with computer vision: A new multi-spatial scale urban fabric dataset and a novel convolutional neural network solution for urban fabric classification tasks
No full textThis paper builds on the proven track record of CNN-based pattern recognition and feature extraction methods, and reports a novel model that classifies urban fabric samples of metropolitan areas in terms of (1) which city they belong to, (2) what types of urban fabric they belong to, and (3) which historic period they originate from. Currently, such tasks require intensive manual work by senior professionals, and even then, inconsistencies and errors occur. Our work is based on a novel urban fabric dataset of four metropolitan areas with distinct typologies (linear development, open block, gated compound, medieval region, irregular grid and orthogonal gird), which consist of high resolution 3-dimensional built form data and hierarchical street networks. The classification model presented in this paper is the first that is capable of predicting the city origin, urban fabric pattern type and construction period. The novelty is also characterised by jointly considering urban fabric features across multiple spatial scales. The experiments demonstrate that this multi-scale approach can capture a wide range of urban fabric features across cities, urban fabric pattern types and development periods. We further find that the effectiveness can be enhanced by appending an auxiliary network for identifying the most appropriate combinations of the multiple spatial scales in line with the classification task. The dataset and model can massively scale up the productivity of researchers and professionals working on cities
Asset Information Model to support the adoption of a digital twin: West Cambridge case study
No full textDigital Twins are an emerging topic in the context of the Built Environment. In addition to being a digital representation of a physical asset, system or process, a digital twin should represent the nuances such as the hierarchy nature of physical assets, relationships between different systems and the workflow of different processes. Furthermore, a digital twin should be agnostic to specific technology solutions and aim to have the ability to support data analytics, Artificial Intelligence (AI) and data standardisation, integration and exchange. This paper presents a BIM-based approach for the design and development of a digital twin. This approach utilises the object-orientated aspect of a BIM model for the creation of an Asset Information Model (AIM), which supports the creation of a DT. Based on a case study of the West Cambridge campus, this paper illustrates the development of a single 3D model for the integration of multiple BIM models with rich metadata attached based on an asset classification schema
High fracture toughness micro-architectured materials
No full text© 2020 We investigate the possibility of achieving high fracture toughness and high strength by the design of lightweight (density below water) metallic micro-architectured materials. The micro-architectured materials were manufactured by drilling a hexagonal array of holes in plates of an aluminum alloy, and the fracture toughness was evaluated via three-point bend tests of single-edge notch specimens. The results show that the fracture toughness of micro-architectured materials increases with increasing relative density and remarkably, a micro-architectured material can be 50% lighter than the parent material but maintain the same fracture toughness. Additional tests on geometrically similar specimens revealed that the fracture toughness increases linearly with the square-root of the cell size. The experiments are complemented by finite element calculations of ductile fracture. In the calculations, the fracture toughness of single-edge notch specimens subjected to three-point bending are evaluated using both, a procedure similar to the experiments and direct computation of the J-contour integral. The fracture toughness as calculated by both methods are consistent with the experimental results. In addition, the calculations are also carried out for single-edge notch specimens subjected to tensile loading, confirming the validity of the measured fracture toughness as a useful material property independent of specimen geometry
Heterostructures formed through abraded van der Waals materials
No full textTo fully exploit van der Waals materials and their vertically stacked heterostructures, new mass-scalable production routes which are low cost but preserve the high electronic and optical quality of the single crystals are required. Here, we demonstrate an approach to realise a variety of functional heterostructures based on van der Waals nanocrystal films produced through the mechanical abrasion of bulk powders. We find significant performance enhancements in abraded heterostructures compared to those fabricated through inkjet printing of nanocrystal dispersions. To highlight the simplicity, applicability and scalability of the device fabrication, we demonstrate a multitude of different functional heterostructures such as resistors, capacitors and photovoltaics. We also demonstrate the creation of energy harvesting devices, such as large area catalytically active coatings for the hydrogen evolution reaction and enhanced triboelectric nanogenerator performance in multilayer films. The ease of device production makes this a promising technological route for up-scalable films and heterostructures
Content-Aware Automated Parameter Tuning for Approximate Color Transforms
No full textThere are numerous approximate color transforms reported in the literature that aim to reduce display power consumption by imperceptibly changing the color content of displayed images. To be practical, these techniques need to be content-aware in picking transformation parameters to preserve perceptual quality. This work presents a computationally-efficient method for calculating a parameter lower bound for approximate color transform parameters based on the content to be transformed. We conduct a user study with 62 participants and 6,400 image pair comparisons to derive the proposed solution. We use the user study results to predict this lower bound reliably with a 1.6% mean squared error by using simple image-color-based heuristics. We show that these heuristics have Pearson and Spearman rank correlation coefficients greater than 0.7 (p<0.01) and that our model generalizes beyond the data from the user study. The user study results also show that the color transform is able to achieve up to 50% power saving with most users reporting negligible visual impairment
Seeking coherence between barriers to manufacturing technology adoption and innovation policy
No full textManufacturing-enabling technologies (MET) play a key role in increasing the reliability of manufacturing processes, and help accelerate new product development and testing. Manufacturing firms are, however, often reluctant to develop MET themselves, as these may not be part of their core competencies nor easily appropriable. Government support can play a vital role in overcoming these barriers for firms. Ideally, this support should be tailored to the barriers associated with a specific technology. Existing studies do not provide insight into how these barriers differ across types of MET. Based on 26 interviews and approximately a hundred sources of archival data, we study the adoption of four types of MET for advanced composite materials in the aviation industry. We analyze what technology-level and market factors affect the adoption of each type of MET, and whether government programs have responded to industry’s needs. We find significant heterogeneity in barriers to the adoption of different METs, and that government programs designed to foster manufacturing innovation do not readily adapt to these variations. In particular, they often do not account for factors such as MET technological interdependence, nature of learning (scientific versus trial-and-error), and the heterogeneity of the technology development community. We provide practitioners with guidelines on how to tailor manufacturing innovation programs to accelerate the development and adoption of different types of MET
Shaping soft robotic microactuators by wire electrical discharge grinding
No full textInflatable soft microactuators typically consist of an elastic material with an internal void that can be inflated to generate a deformation. A crucial feature of these actuators is the shape of ther inflatable void as it determines the bending motion. Due to fabrication limitations, low complex void geometries are the de facto standard, severely restricting attainable motions. This paper introduces wire electrical discharge grinding (WEDG) for shaping the inflatable void, increasing their complexity. This approach enables the creation of new deformation patterns and functionalities. The WEDG process is used to create various moulds to cast rubber microactuators. These microactuators are fabricated through a bonding-free micromoulding process, which is highly sensitive to the accuracy of the mould. The mould cavity (outside of the actuator) is defined by micromilling, whereas the mould insert (inner cavity of the actuator) is defined by WEDG. The deformation patterns are evaluated with a multi-segment linear bending model. The produced microactuators are also characterised and compared with respect to the morphology of the inner cavity. All microactuators have a cylindrical shape with a length of 8 mm and a diameter of 0.8 mm. Actuation tests at a maximum pressure of 50 kPa indicate that complex deformation patterns such as curling, differential bending or multi-points bending can be achieved
Ballooning, bulging, and necking: An exact solution for longitudinal phase separation in elastic systems near a critical point.
No full textProminent examples of longitudinal phase separation in elastic systems include elastic necking, the propagation of a bulge in a cylindrical party balloon, and the beading of a gel fiber subject to surface tension. Here we demonstrate that if the parameters of such a system are tuned near a critical point (where the difference between the two phases vanishes), then the behavior of all systems is given by the minimization of a simple and universal elastic energy familiar from Ginzburg-Landau theory in an external field. We minimize this energy analytically, which yields not only the well known interfacial tanh solution, but also the complete set of stable and unstable solutions in both finite and infinite length systems, unveiling the elastic system's full shape evolution and hysteresis. Correspondingly, we also find analytic results for the the delay of onset, changes in criticality, and ultimate suppression of instability with diminishing system length, demonstrating that our simple near-critical theory captures much of the complexity and choreography of far-from-critical systems. Finally, we find critical points for the three prominent examples of phase separation given above, and demonstrate how each system then follows the universal set of solutions
Exploring the influence of socio-historical constructs on BIM implementation: an activity theory perspective
No full textBuilding Information Modelling (BIM) has been widely seen as bringing a paradigm change to the construction industry. However, scholars have acknowledged that neither widespread BIM implementation nor the envisaged systemic changes within the sector have taken place. Despite acknowledging that the industry’s conditions and embedded contexts shape innovation diffusion, existing studies have not explored in any depth “how” the context might influence the episode of change when a new technology is introduced and the new practices accompanying that technology and old practices co-evolve. By adopting activity theory, its concepts of contradictions and multiple layers within the activity system, in this paper, we explore the interaction between situated and existing practices, or the “how” of implementation; that is, how the activity system is questioned and redefined during an episode of technological change. Drawing on data from multiple case studies, our findings demonstrate that situated practices related to the definition of information requirements, and the production and the handover of information were re-enacted following institutionalised socio-historical constructs (e.g. norms, rules, division of labour) at the industry and organisational levels. The findings provide insights regarding the inertia in the transformation of the sector as also deriving from re-enactments of socio-historical constructs that mediate the institutionalisation of situated practices. Our findings reveal re-enactment as part of the transformation process and contribute to calls for more realistic views on BIM implementation
Creep behaviour and tensile response of adhesively bonded polyethylene joints: Single-Lap and Double-Strap
No full text© 2020 Elsevier Ltd The static and time-dependent behaviours of adhesively bonded polyethylene Double-Strap (DS) joints were investigated to assess the viability of this joint configuration relative to the Single-Lap (SL) joints. Both experiments and finite element simulations are conducted. First, we individually characterise the tensile and creep behaviour of the adhesive and adherent materials; an epoxy-based adhesive and polyethylene, respectively. This information is used to develop suitable constitutive models that are then implemented in the commercial finite element package ABAQUS by means of user material subroutines, UMATs. The numerical models are used to design the creep tests on the adhesive joints. Afterwards, an extensive experimental campaign is conducted where we characterise the static and creep behaviour of two joint configurations, SL and DS joints, and three selected values of the overlap length. In regard to the static case, results reveal an increase in the failure load with increasing overlap length, of up to 10% for an overlap length of 39 mm. Also, slightly better performance is observed for the SL joint configuration. For the creep experiments, we show that the DS adhesive joint configuration leads to much shorter elongations, relative to the SL joints. These differences diminish with increasing overlap length but remain substantial in all cases. In both joint configurations, the elongation increases with decreasing overlap length. For instance, increasing the overlap length to 39 mm led to a 50% and a 30% reduction in elongation for SL and DS joints, respectively. Moreover, the numerical predictions show a good agreement with the experiments. The stress redistribution is investigated and it is found that the shear stress is highly sensitive to the testing time, with differences being more noticeable for the DS joint system. The findings bring insight into the creep behaviour of polyethylene-based adhesive joints, a configuration of notable industrial interest