Legal considerations for using digital twins in additive manufacture a review of the literature

Rapid technological change presents new opportunities and reveals new risks, challenging existing governance arrangements. The fusion of Industry 4.0 technologies combines with Additive Manufacturing (AM) to create new business solutions. Legal issues with AM are well documented, for example Daly[1] explores the interaction of 3D printing with the law, identifying Intellectual Property, Product Liability and Data Privacy as areas of importance. However, this technology fusion has also enabled improved real-time digital representation, monitoring, simulation and control of the physical delivered through applications of Digital Twin. Such Digital Twins are prevalent in manufacturing and in AM can potentially provide assurance that a printed item meets specified requirements. However, additional legal considerations are emerging. This paper illustrates these by examining the attributes of "Digital Twins in Additive Manufacture Use Cases" revealed through literature

Radiation properties of truncated cones to enhance the beam patterns of air-coupled transducers

Radiation properties of cones are used to steer energy from the side lobes toward the center of the beam pattern of an air-coupled source. Two structures of superposed truncated cones are designed and implemented in a finite element package to modify the beam pattern of a piston model simulating an air-coupled transducer. Results show how the energy from the sides of the beam is conveyed toward the center of it thus widening the main lobe angular domain and smoothing the beam curve. This work is intended to support methods for range estimation performed with air-coupled transducers and localization strategies with broadband ultrasonic signals, as well as to investigate mathematical relationships at the base of radiation properties of conical structures

Evaluation and validation of Damage Assessment Tracking Criteria models within the sector of UK automotive remanufacturing

This paper details the specific aims and purposes of the Damage Assessment Tracking Criteria; a series of evaluation tools designed to aid in remanufacturing inspection operations. The background and justification of this model, which is detailed in a separate work, identifies ill definition and an over reliance on opinion as barriers to effective inspection activities. Analysis of this issue led to the building of the Damage Assessment Tracking Criteria; a 4-model foundation that aims to provide a more comprehensive and more structured approach to the inspection stages of the typical remanufacturing process. Through expert opinion this model was evaluated multiple times. One review was used to gauge the level of idea communication within an academic situation, this was followed up by external industrial reviews of the model by those most likely to utilise it during industry practice. After extensive feedback and modification the final model assessment was carried out with an expert panel that were instructed to be as critical as possible with the model in order to ensure that its evaluation was as robust as possible. The results of these reviews were all on the positive side of the scale. Multiple statements regarding the potential value and suitability of each model aspect and justification for their use was presented in the format of an evaluation form which was used by those involved to present their findings and feedback. Negative feedback was addressed and successful modification yielding more positive results in the next evaluation was achieved. Though walking the line between specificity and generic was noted to be the most difficult factor to consider when developing the models, the final findings of the evaluation show that significant value was perceived by those operating within industry. The potential benefits of customised variants of the models is acknowledged by all parties as a possible future avenue of research

Extreme call amplitude from near-field acoustic wave coupling in the stridulating water insect Micronecta scholtzi (Micronectinae)

Underwater acoustic transducers, particularly at low frequencies, are beset by problems of scale and inefficiency due to the large wavelengths of sound in water. In insect mating calls, a high call volume is usually desirable, increasing the range of signal transmission and providing a form of advertisement of the signaller's quality to a potential mate; however, the strength of the call is constrained by body size and by the need to avoid predators who may be listening in. Male crickets and water boatmen avoid some of the limitations of body size by exploiting resonant structures, which produce sharply tuned species specific songs, but call frequency and volume remain linked to body size. Recently, the water boatman Micronecta scholtzi was found to circumvent this rule, producing a louder mating call than that of similar, but much larger, Corixa. The resonant structure in Corixidae and Micronectinae is believed to be the trapped air reserves around the insect as it dives, driven by a stridulatory apparatus. However, the method by which energy is transferred from the striated area to the bubble is unknown. Here, we present modelling of a system of near-field coupling of acoustic sources to bubbles showing an exponential increase in sound power gain with decreasing distance that provides a simple solution to the stimulus of the air bubbles in Corixidae and Micronectinae and explains the discrepancy of M. scholtzi's extreme call volume. The findings suggest a possible route to engineered systems using near-field coupling to overcome size constraints in low-frequency (less than 500 Hz) underwater transducers, where the input efficiency of a piezoelectric device can be coupled through the hydrodynamic field to the high radiative efficiency of a near-ideal monopole emitter

Housing influence on multi-band directional MEMS microphones inspired by Ormia ochracea

A new bio-inspired multi-band directional MEMS microphone based on the hearing properties of the fly Ormia ochracea is presented, together with the behavioral influence of 3D-printed housings. The multi-user foundry fabricated microphone operates on four frequency bands, all below 10 kHz and acts as a pressure gradient directional microphone with figure of eight polar pattern, or as an omni-directional microphone depending on the housing. The influence of an open or closed backside housing on the frequency response and directionality is shown, leading to the loss of directionality with no acoustic access to the backside of the fly-ear inspired microphone membrane

The Marinoan cap carbonate of Svalbard: Syngenetic marine dolomite with ¹⁷O-anomalous carbonate‐associated sulphate

Two cap carbonates overlying Cryogenian panglacial deposits are found in North- East Svalbard of which the younger (635 Ma) forms the base of the Ediacaran Period. It is represented by a transgressive succession in which laminated do-lostone, typically around 20 m thick (Member D1), is succeeded transitionally by a similar thickness of impure carbonates (Member D2). In Spitsbergen, there is evidence of microbially influenced sediment stabilisation and carbonate precipitation in the lower part of D1, whilst the upper part of D1 and D2 show centimetre- decimetre- scale graded units with undulatory lamination interpreted as evidence of storm activity. Carbonate originated as possible freshwater whitings, as well as microbial precipitates. Exhumed and eroded hardgrounds display replacive 10– 30 μm dolomite crystals with cathodoluminescence characteris-tics consistent with early diagenetic manganese and iron reduction. Regionally, carbon isotope values consistently decrease by around 2‰ from around −3‰ over 30 m of section which is both a temporal and a bathymetric signal, but not a global one. An exponential decline in carbonate production predicted by box models is fitted by a semi- quantitative sedimentation model. A mass- anomalous 17O depletion in carbonate- associated sulphate in dolomite, inherited from pre-cursor calcite, decreases from −0.6 to −0.3‰ in the basal 15 m of section and then approaches background values. The post- glacial anomalous 17O depletion in carbonate- associated sulphate and barite elsewhere has been interpreted in terms of ultra- high pCO2 at the onset of deglaciation. Such anomalies, with larger amplitude, have been reported in Svalbard from underlying lacustrine and tufa-ceous limestones representing a hyperarid glacial environment. The anomalous sulphate could be produced contemporarily, or the internally drained landscape may have continued to release 17O-anomalous sulphate as it was transgressed during cap carbonate deposition. The late Cryogenian to earliest Ediacaran record in Svalbard provides the most complete record of the basal 17O - depletion event in the world

Additive manufacturing (AM) capacitive acoustic and ultrasonic transducers using a commercial direct light processing (DLP) printer

In recent years, there has been increasing interest in using additive manufacturing (3D printing) technology to fabricate sensors and actuators due to rapid prototyping, low-cost manufacturing processes, customized features and the ability to create complex geometries at micrometre scale. State of the art additive manufactured acoustic and ultrasonic transducers show limitations in miniaturization, repeatability (defects) and sensitivity. This new work encompasses the development of a capacitive acoustic and ultrasonic transducer, including its fabrication process using a commercial digital light processing printer and output signal characterization with a custom-made amplification circuit. A set of capacitive acoustic and ultrasonic transducers was fabricated and tested using different diaphragm diameters from 1.8 -2.2mm, for comparison, with central operating frequency between 19 -54 kHz, respectively. This capacitive transducer design has a receiving sensitivity of up to 0.4 mV/Pα at its resonant frequency, and a comparison with a commercial reference microphone is provided

Engineered 3D hydrogels with full-length fibronectin that sequester and present growth factors

[EN] Extracellular matrix (ECM)-derived matrices such as Matrigel are used to culture numerous cell types in vitro as they recapitulate ECM properties that support cell growth, organisation, migration and differentiation. These ECM-derived matrices contain various growth factors which make them highly bioactive. However, they suffer lot-to-lot variability, undefined composition and lack of controlled physical properties. There is a need to develop rationally designed biomaterials that can also recapitulate ECM roles. Here, we report the development of fibronectin (FN)-based 3D hydrogels of controlled stiffness and degradability that incorporate full-length FN to enable solid-phase presentation of growth factors in a physiological manner. We demonstrate, in vitro and in vivo, the effect of incorporating vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2) in these hydrogels to enhance angiogenesis and bone regeneration, respectively. These hydrogels represent a step-change in the design of well-defined, reproducible, synthetic microenvironments for 3D cell culture that incorporate growth factors to achieve functional effects.This study was supported by the UK Regenerative Medicine Platform (MRC grant MR/L022710/1), the UK Engineering and Physical Sciences Research Council (EPSRC EP/P001114/1) and a programme grant from the Sir Bobby Charlton Foundation. mu CT work was supported by the European Research Council (ERC) under the European Union's Seventh Framework Programme (FP7/2007-2013) (grant agreement No. [615030]). S.T. acknowledges support from the University of Glasgow through their internal scholarship funding program. We thank the support of David Adams (Anatomy lab, University of Glasgow) and the Biological Services and Veterinary Research Facility (University of Glasagow) for their assistance.Trujillo-Muñoz, S.; González-García, C.; Rico Tortosa, PM.; Reid, A.; Windmill, J.; Dalby, MJ.; Salmerón Sánchez, M. (2020). Engineered 3D hydrogels with full-length fibronectin that sequester and present growth factors. Biomaterials. 252:1-15. https://doi.org/10.1016/j.biomaterials.2020.120104S115252Jarad, M., Kuczynski, E. A., Morrison, J., Viloria-Petit, A. M., & Coomber, B. L. (2017). Release of endothelial cell associated VEGFR2 during TGF-β modulated angiogenesis in vitro. BMC Cell Biology, 18(1). doi:10.1186/s12860-017-0127-ySpence, J. R., Mayhew, C. N., Rankin, S. A., Kuhar, M. F., Vallance, J. E., Tolle, K., … Wells, J. M. (2010). Directed differentiation of human pluripotent stem cells into intestinal tissue in vitro. Nature, 470(7332), 105-109. doi:10.1038/nature09691Yang, S.-J., Son, J. 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Characterization of (0-3) piezocomposite materials for transducer applications

In this study, we have developed and characterized two different (0-3) piezoelectric composite materials with potential to be used in sensing applications. The composite materials were made using Polydimethylsiloxane (PDMS) as the polymer matrix with Barium Titanate (BaTiO3), and Lead Zirconate Titanate (PZT51) as the dielectric fillers. Thin film samples of the (0-3) piezocomposites were prepared using a solution mixing and spin coating method to produce composites with (0-3) connectivity pattern and layer thickness of mathbf{100} mumathbf{m}, The microstructure of the piezocomposites were analyzed using a scanning electron microscope to determine the connectivity structure and homogeneity of the piezocomposites. The mechanical properties of the composites were determined using the method of Oliver and Pharr. FTIR analysis was used to determine the effects of the fillers on the structure of the piezocomposite. The average piezoelectric pmb{d}{mathit{33}} coefficient of the piezocomposites were also measured using the laser vibrometer technique and determined to be 30 pm/V for the piezocomposite consisting of Barium Titanate (BaTiO3) and 32 pm/V for the piezocomposite consisting of Lead Zirconate Titanate (PZT51)

Material stiffness variation in mosquito antennae

The antennae of mosquitoes are model systems for acoustic sensation, in that they obey general principles for sound detection, using both active feedback mechanisms and passive structural adaptations. However, the biomechanical aspect of the antennal structure is much less understood than the mechano-electrical transduction. Using confocal laser scanning microscopy, we measured the fluorescent properties of the antennae of two species of mosquito – Toxorhynchites brevipalpis and Anopheles arabiensis – and, noting that fluorescence is correlated with material stiffness, we found that the structure of the antenna is not a simple beam of homogeneous material, but is in fact a rather more complex structure with spatially distributed discrete changes in material properties. These present as bands or rings of different material in each subunit of the antenna, which repeat along its length. While these structures may simply be required for structural robustness of the antennae, we found that in FEM simulation, these banded structures can strongly affect the resonant frequencies of cantilever-beam systems, and therefore taken together our results suggest that modulating the material properties along the length of the antenna could constitute an additional mechanism for resonant tuning in these species