Evaporation, lifetime, and robustness studies of liquid marbles for collision-based computing

© 2018 American Chemical Society. Liquid marbles (LMs) have recently attracted interest for use as cargo carriers in digital microfluidics and have successfully been implemented as signal carriers in collision-based unconventional computing circuits. Both application domains require LMs to roll over substantial distances and to survive a certain number of collisions without degrading. To evaluate the lifetime of LMs being subjected to movement and impact stresses, we have selected four types of coating to investigate: polytetrafluoroethylene (PTFE), ultrahigh density polyethylene (PE), Ni, and a mixture of Ni with PE (Ni-PE). Hierarchies of robustness have been constructed which showed that pure PE LMs survived the longest when stationary and in motion. Pure PTFE LMs were shown to be the least resilient to multiple impacts. The PTFE coating provided minimal protection against evaporative losses for small LM volumes (2 and 5 μL) however, larger LMs (10 μL) were shown to have good evaporative stabilities when stationary. Conversely, PE LMs showed a remarkable ability to withstand multiple impacts and were also stable when considering just passive evaporation. Hybrid Ni-PE LMs exhibited more resilience to multiple impacts compared to Ni LMs. Thus, when designing LM devices, it is paramount to determine impact pathways and select appropriate coating materials

Sparse and Constrained Stochastic Predictive Control for Networked Systems

This article presents a novel class of control policies for networked control of Lyapunov-stable linear systems with bounded inputs. The control channel is assumed to have i.i.d. Bernoulli packet dropouts and the system is assumed to be affected by additive stochastic noise. Our proposed class of policies is affine in the past dropouts and saturated values of the past disturbances. We further consider a regularization term in a quadratic performance index to promote sparsity in control. We demonstrate how to augment the underlying optimization problem with a constant negative drift constraint to ensure mean-square boundedness of the closed-loop states, yielding a convex quadratic program to be solved periodically online. The states of the closed-loop plant under the receding horizon implementation of the proposed class of policies are mean square bounded for any positive bound on the control and any non-zero probability of successful transmission

Neuromorphic liquid marbles with aqueous carbon nanotube cores

Neuromorphic computing devices attempt to emulate features of biological nervous systems through mimicking the properties of synapses, towards implementing the emergent properties of their counterparts, such as learning. Inspired by recent advances in the utilisation of liquid marbles (microlitre quantities of fluid coated in hydrophobic powder) for the creation of unconventional computing devices, we describe the development of liquid marbles with neuromorphic properties through the use of copper coatings and l.0mgml-1 carbon nanotube-containing fluid cores. Experimentation was performed through sandwiching the marbles between two cup-style electrodes and stimulating them with repeated DC pulses at 3.0 V. Our results demonstrate that 'entrainment∗ of a carbon nanotube filled-copper liquid marble via periodic pulses can cause their electrical resistance to rapidly switch between high to low resistance profiles, upon inverting the polarity of stimulation: The reduction in resistance between high and low profiles was approximately 88% after two rounds of entrainment. This effect was found to be reversible through reversion to the original stimulus polarity and was strengthened by repeated experimentation, as evidenced by a mean reduction in time to switching onset of 43%. These effects were not replicated in nanotube solutions not bound inside liquid marbles. Our electrical characterisation also reveals that nanotube-filled liquid marbles exhibit pinched loop hysteresis IV profiles consistent with the description of memristors. We conclude by discussing the applications of this technology to the development of unconventional computing devices and the study of emergent characteristics in biological neural tissue

Simulations of idealised 3D atmospheric flows on terrestrial planets using LFRic-Atmosphere

We demonstrate that LFRic-Atmosphere, a model built using the Met Office's GungHo dynamical core, is able to reproduce idealised large-scale atmospheric circulation patterns specified by several widely-used benchmark recipes. This is motivated by the rapid rate of exoplanet discovery and the ever-growing need for numerical modelling and characterisation of their atmospheres. Here we present LFRic-Atmosphere's results for the idealised tests imitating circulation regimes commonly used in the exoplanet modelling community. The benchmarks include three analytic forcing cases: the standard Held-Suarez test, the Menou-Rauscher Earth-like test, and the Merlis-Schneider Tidally Locked Earth test. Qualitatively, LFRic-Atmosphere agrees well with other numerical models and shows excellent conservation properties in terms of total mass, angular momentum and kinetic energy. We then use LFRic-Atmosphere with a more realistic representation of physical processes (radiation, subgrid-scale mixing, convection, clouds) by configuring it for the four TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI) scenarios. This is the first application of LFRic-Atmosphere to a possible climate of a confirmed terrestrial exoplanet. LFRic-Atmosphere reproduces the THAI scenarios within the spread of the existing models across a range of key climatic variables. Our work shows that LFRic-Atmosphere performs well in the seven benchmark tests for terrestrial atmospheres, justifying its use in future exoplanet climate studies.Comment: 34 pages, 9(12) figures; Submitted to Geoscientific Model Development; Comments are welcome (see Discussion tab on the journal's website: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-647

Drop-coated Titanium Dioxide Memristors

The fabrication of memristors by drop-coating sol-gel Ti(OH)$_4$ solution onto either aluminium foil or sputter-coated aluminium on plastic is presented. The gel layer is thick, 37$\mu$m, but both devices exhibit good memristance I-V profiles. The drop coated aluminium foil memristors compare favourably with the sputter-coated ones, demonstrating an expansion in the accessibility of memristor fabrication. A comparison between aluminium and gold for use as the sputter-coated electrodes shows that aluminium is the better choice as using gold leads to device failure. The devices do not require a forming step.Comment: 9 figures. arXiv admin note: substantial text overlap with arXiv:1106.629

Mapping outcomes of liquid marble collisions

© 2019 The Royal Society of Chemistry. Liquid marbles (LMs) have many promising roles in the ongoing development of microfluidics, microreactors, bioreactors, and unconventional computing. In many of these applications, the coalescence of two LMs is either required or actively discouraged, therefore it is important to study liquid marble collisions and establish parameters which enable the desired collision outcome. Recent reports on LM coalescence have focused on either two mobile LMs colliding, or an accelerating LM hitting a sessile LM with a backstop. A further possible scenario is the impact of a mobile LM against a non-supported static LM. This paper investigates such a collision, using high-speed videography for single-frame analysis. Multiple collisions were undertaken whilst varying the modified Weber number (We∗) and offset ratios (X∗). Parameter ranges of 1.0 0.25, and We∗ 1.55 resulted in 100% non-coalescence. Additionally, observations of LMs moving above a threshold velocity of 0.6 m s -1 have revealed a new and unusual deformation. Comparisons of the outcome of collisions whilst varying both the LM volume and the powder grain size have also been made, revealing a strong link. The results of this work provide a deeper understanding of LM coalescence, allowing improved control when designing future collision experiments

Chronic elevation of pulmonary microvascular pressure in chronic heart failure reduces bi-directional pulmonary fluid flux

Aims. Chronic heart failure leads to pulmonary vascular remodelling and thickening of the alveolar–capillary barrier. We examined whether this protective effect may slow resolution of pulmonary oedema consistent with decreased bi-directional fluid flux. Methods and results. Seven weeks following left coronary artery ligation, we measured both fluid flux during an acute rise in left atrial pressure (n = 29) and intrinsic alveolar fluid clearance (n = 45) in the isolated rat lung. Chronic elevation of pulmonary microvascular pressure prevented pulmonary oedema and decreased lung compliance when left atrial pressure was raised to 20 cmH2O, and was associated with reduced expression of endothelial aquaporin 1 (P = 0.03). However, no other changes were found in mediators of fluid flux or cellular fluid channels. In isolated rat lungs, chronic LV dysfunction (LV end-diastolic pressure and infarct circumference) was also inversely related to alveolar fluid clearance (P ≤ 0.001). The rate of pulmonary oedema reabsorption was estimated by plasma volume expansion in eight patients with a previous clinical history of chronic heart failure and eight without, who presented with acute pulmonary oedema. Plasma volume expansion was reduced at 24 h in those with chronic heart failure (P = 0.03). Conclusions. Chronic elevation of pulmonary microvascular pressure in CHF leads to decreased intrinsic bi-directional fluid flux at the alveolar–capillary barrier. This adaptive response defends against alveolar flooding, but may delay resolution of alveolar oedema.A National Health and Medical Research Council (NHMRC) grant (#375129); Australian and New Zealand College of Anaesthetists (ANZCA) grant (#08/020); the Flinders Medical Centre Foundation

Teaching emergency and disaster management in Australia: standards for higher education providers

The need for emergency and disaster professionals with multidisciplinary knowledge and holistic understanding is widely recognised. Despite this, there is currently no international nor an Australian consensus on a set of common standards for higher education that could ensure graduates possess knowledge and skills with sufficient commonality to facilitate interoperability in all facets of disaster management cycle. Thus, this research project aimed to develop a standards and an associated conceptual framework for higher education programs in emergency and disaster management. The Generic Emergency and Disaster Management Standards (GEDMS) were developed through a mixed qualitative research approach involving a systematic literature review, mapping of current course content offered in Australia and New Zealand, focus groups of experts and consultation with policy makers, industry representatives and other relevant stakeholders. The Standards consist of three main domains: knowledge, skills and application. Governance and policy frameworks, theoretical and conceptual basis for practice, and contemporary disaster management were identified as underlying themes for the knowledge domain. Leadership, communication, and collaboration were fitted under the skills domain. The professional practice, together with critical thinking, were considered the means by which knowledge and skills are applied