Modelling the Non-equilibrium Electric Double Layer at Oil-pressboard Interface of High Voltage Transformers

In large oil-filled power transformers, cellulose-based pressboard and paper are used throughout for electrical insulation. Microscopic views have shown that pressboard insulation is a fibrous and porous structure with non-homogeneous surface. It has been recognised that the pressboard structure is more porous towards the edge [1]. The pores within the pressboard allow oil absorption during impregnation process and provide paths for oil to penetrate until saturation is reached. The ratio of fibre and oil changes as the material structure changes from a medium of bulk oil-pressboard composite toward the bulk oil medium. The porosity of pressboard can also result in impurities within the oil being drawn into the pressboard. It has also been recognised that physicochemical process of a liquid in contact with solid wall leads to the formation of electric double layer (EDL) in the liquid region [2, 3]. The material properties and geometry of pressboard thus lead to a complex oil-pressboard interface. A 2-D model of oil-pressboard interface has been constructed using Comsol Multiphysics Finite Element Analysis software and this is shown in Figure 1. The mathematical model considers the dissociation of a generic impurity in the oil into positive and negative ions and considers the role of the porous and non-homogeneous wall of pressboard in the formation of the EDL. The pressboard, which is represented by different arrays of fibre, promotes preferential adsorption and desorption processes between ions in the oil and unoccupied fibre surfaces of oil impregnated pressboard. The model studies the non-equilibrium charge density profile in the EDL at the oil-pressboard interface when the oil is in the stationary condition

Empirically inspired simulated electro-mechanical model of the rat mystacial follicle-sinus complex

In whiskered animals, activity is evoked in the primary sensory afferent cells (trigeminal nerve) by mechanical stimulation of the whiskers. In some cell populations this activity is correlated well with continuous stimulus parameters such as whisker deflection magnitude, but in others it is observed to represent events such as whisker-stimulator contact or detachment. The transduction process is mediated by the mechanics of the whisker shaft and follicle-sinus complex (FSC), and the mechanics and electro-chemistry of mechanoreceptors within the FSC. An understanding of this transduction process and the nature of the primary neural codes generated is crucial for understanding more central sensory processing in the thalamus and cortex. However, the details of the peripheral processing are currently poorly understood. To overcome this deficiency in our knowledge, we constructed a simulated electro-mechanical model of the whisker-FSC-mechanoreceptor system in the rat and tested it against a variety of data drawn from the literature. The agreement was good enough to suggest that the model captures many of the key features of the peripheral whisker system in the rat

Predictive prey pursuit in a whiskered robot

Highly active small mammals need to capture prey rapidly and with a high success rate if they are to survive. We consider the case of the Etruscan shrew, which hunts prey including crickets almost as large as itself, and relies on its whiskers (vibrissae) to complete a kill. We model this hunting behaviour using a whiskered robot. Shrews strike rapidly and accurately after gathering very limited sensory information; we attempt to match this performance by using model-based simultaneous discrimination and localisation of a ‘prey’ robot (i.e. by using strong priors). We report performance that is comparable, given the spatial and temporal scale differences, to shrew performance in most respects

Brain-inspired Bayesian perception for biomimetic robot touch

Studies of decision making in animals suggest a neural mechanism of evidence accumulation for competing percepts according to Bayesian sequential analysis. This model of perception is embodied here in a biomimetic tactile sensing robot based on the rodent whisker system. We implement simultaneous perception of object shape and location using two psychological test paradigms: first, a free-response paradigm in which the agent decides when to respond, implemented with Bayesian sequential analysis; and second an interrogative paradigm in which the agent responds after a fixed interval, implemented with maximum likelihood estimation. A benefit of free-response Bayesian perception is that it allows tuning of reaction speed against accuracy. In addition, we find that large gains in decision performance are achieved with unforced responses that allow null decisions on ambiguous data. Therefore free-response Bayesian perception offers benefits for artificial systems that make them more animal-like in behavior

Naive Bayes novelty detection for a moving robot with whiskers

Novelty detection would be a useful ability for any autonomous robot that seeks to categorize a new environment or notice unexpected changes in its present one. A biomimetic robot (SCRATCHbot) inspired by the rat whisker system was here used to examine the performance of a novelty detection algorithm based on a 'naive' implementation of Bayes rule. Naive Bayes algorithms are known to be both efficient and effective, and also have links with proposed neural mechanisms for decision making. To examine novelty detection, the robot first used its whiskers to sense an empty floor, after which it was tested with a textured strip placed in its path. Given only its experience of the familiar situation, the robot was able to distinguish the novel event and localize it in time. Performance increased with the number of whiskers, indicating benefits from integrating over multiple streams of information. Considering the generality of the algorithm, we suggest that such novelty detection could have widespread applicability as a trigger to react to important features in the robot's environment. © 2010 IEEE

Feasibility of Prehospital Emergency Anesthesia in the Cabin of an AW169 Helicopter Wearing Personal Protective Equipment During Coronavirus Disease 2019

OBJECTIVE: Pre-hospital emergency anaesthesia in the form of rapid sequence intubation (RSI) is a critical intervention delivered by advanced pre-hospital critical care teams. Our previous simulation study determined the feasibility of in-aircraft RSI. We now examine whether this feasibility is preserved in a simulated setting, when clinicians wear personal protective equipment (PPE) for aerosol-generating procedures (AGP) for in-aircraft, on-the-ground RSI. METHODS: Air Ambulance Kent Surrey Sussex is a Helicopter Emergency Medical Service (HEMS) which utilises an AW169 cabin simulator. Wearing full AGP PPE (eye protection, FFP3 mask, gown, gloves), 10 doctor-paramedic teams performed RSI in a standard “can intubate, can ventilate” scenario and a “can't intubate, can't oxygenate” (CICO) scenario. Pre-specified timings were reported, and participant feedback was sought by questionnaire. RESULTS: RSI was most commonly performed by direct laryngoscopy and was successfully achieved in all scenarios. Time to completed endotracheal intubation (ETI) was fastest (287s) in the standard scenario and slower (370s, p=.01) in the CICO scenario. Time to ETI was not significantly delayed by wearing PPE in the standard (p=.19) or CICO variant (p=.97). Communication challenges, equipment complications and PPE difficulties were reported, but ways to mitigate these also reported. CONCLUSION: In-aircraft RSI (aircraft on-the-ground) whilst wearing PPE for AGPs had no significant impact on time to successful completion of ETI in a simulated setting. Patient safety is paramount in civilian HEMS, but the adoption of in-aircraft RSI could confer significant patient benefit in terms of pre-hospital time saving and further research is warranted

Storage capacity of a constructive learning algorithm

Upper and lower bounds for the typical storage capacity of a constructive algorithm, the Tilinglike Learning Algorithm for the Parity Machine [M. Biehl and M. Opper, Phys. Rev. A {\bf 44} 6888 (1991)], are determined in the asymptotic limit of large training set sizes. The properties of a perceptron with threshold, learning a training set of patterns having a biased distribution of targets, needed as an intermediate step in the capacity calculation, are determined analytically. The lower bound for the capacity, determined with a cavity method, is proportional to the number of hidden units. The upper bound, obtained with the hypothesis of replica symmetry, is close to the one predicted by Mitchinson and Durbin [Biol. Cyber. {\bf 60} 345 (1989)].Comment: 13 pages, 1 figur

Thinking about the future: Comparing children’s forced-choice versus “generative” responses in the “spoon test”

Episodic future thinking has been assessed in children using the “spoon test”. In this test, children select an item that will be useful in the future. We adapted this test so that preschoolers had to verbally generate the item. For all age groups generating the correct item was more difficult than selecting it. Performance in the “generate” condition was related to category fluency. One of the most popular methods to assess children’s foresight is to present children with a problem (e.g., locked box with no key) in one room and then later, in another room, give them the opportunity to select the item (e.g., key) that will solve it. Whether or not children choose the correct item to bring back to the first room is the dependent measure of interest in this “spoon test.” Although children as young as 3 or 4 years typically succeed on this test, whether they would pass a more stringent version in which they must verbally generate (vs. select) the correct item in the absence of any cues is unknown. This is an important point given that humans must often make decisions about the future without being explicitly “prompted” by the future-oriented option. In Experiment 1, using an adapted version of the spoon test, we show that as the “generative” requirements of the task increase, 3-, 4-, and 5-year-olds’ (N = 99) performance significantly decreases. We replicate this effect in Experiment 2 (N = 48 3-, 4-, and 5-year-olds) and also provide preliminary evidence that the capacity to verbally generate the correct item in a spoon test may draw more heavily on children’s category fluency skills than does their capacity to select this item among a set of distracters. Our findings underscore the importance of examining more generative forms of future thought in young children

A biomimetic vocalisation system for MiRo

There is increasing interest in the use of animal-like robots in applications such as companionship and pet therapy. However, in the majority of cases it is only the robot's physical appearance that mimics a given animal. In contrast, MiRo is the first commercial biomimetic robot to be based on a hardware and software architecture that is modelled on the biological brain. This paper describes how MiRo's vocalisation system was designed, not using pre-recorded animal sounds, but based on the implementation of a real-time parametric general-purpose mammalian vocal synthesiser tailored to the specific physical characteristics of the robot. The novel outcome has been the creation of an 'appropriate' voice for MiRo that is perfectly aligned to the physical and behavioural affordances of the robot, thereby avoiding the 'uncanny valley' effect and contributing strongly to the effectiveness of MiRo as an interactive device

Tactile Discrimination Using Template Classifiers: Towards a Model of Feature Extraction in Mammalian Vibrissal Systems

Rats and other whiskered mammals are capable of making sophisticated sensory discriminations using tactile signals from their facial whiskers (vibrissae). As part of a programme of work to develop biomimetic technologies for vibrissal sensing, including whiskered robots, we are devising algorithms for the fast extraction of object parameters from whisker deflection data. Previous work has demonstrated that radial distance to contact can be estimated from forces measured at the base of the whisker shaft. We show that in the case of a moving object contacting a whisker, the measured force can be ambiguous in distinguishing a nearby object moving slowly from a more distant object moving rapidly. This ambiguity can be resolved by simultaneously extracting object position and speed from the whisker deflection time series – that is by attending to the dynamics of the whisker’s interaction with the object. We compare a simple classifier with an adaptive EM (Expectation Maximisation) classifier. Both systems are effective at simultaneously extracting the two parameters, the EM-classifier showing similar performance to a handpicked template classifier. We propose that adaptive classification algorithms can provide insights into the types of computations performed in the rat vibrissal system when the animal is faced with a discrimination task