The assessment of viscoelastic models for nonlinear soft materials

The increasing use of soft materials in robotics applications requires the development of mathematical models to describe their viscoelastic and nonlinear properties. The traditional linear viscoelastic models are unable to describe nonlinear strain-dependent behaviors. This limitation has been addressed by implementing a piecewise linearization (PL) in the simplest viscoelastic model, the Standard Linear Solid (SLS). In this work, we aim to implement the PL in a more complex model, the Wiechert model and compare the stress response of both linearized models. Therefore, the experimental data from the stress relaxation and tensile strength tests of six rubber-based materials is used to approximate the spring and dashpot constants of the SLS and the Wiechert model. Prior to implement the PL into the stress-strain curve of each material, the stress response from the Maxwell branches must be subtracted from this curve. By using the parameters obtained from fitting the Wiechert model into the stress relaxation curve, the response of both linearized models was improved. Due to the selection of constitutive equations evaluated, the linearized SLS model described the stress-strain curve more accurately. Finally, this work describes in details every step of the fitting process and highlights the benefits of using linearization methods to improve known models as an alternative of using highly complex models to describe the mechanical properties of soft materials

An integrated probabilistic framework for robot perception, learning and memory

Learning and perception from multiple sensory modalities are crucial processes for the development of intelligent systems capable of interacting with humans. We present an integrated probabilistic framework for perception, learning and memory in robotics. The core component of our framework is a computational Synthetic Autobiographical Memory model which uses Gaussian Processes as a foundation and mimics the functionalities of human memory. Our memory model, that operates via a principled Bayesian probabilistic framework, is capable of receiving and integrating data flows from multiple sensory modalities, which are combined to improve perception and understanding of the surrounding environment. To validate the model, we implemented our framework in the iCub humanoid robotic, which was able to learn and recognise human faces, arm movements and touch gestures through interaction with people. Results demonstrate the flexibility of our method to successfully integrate multiple sensory inputs, for accurate learning and recognition. Thus, our integrated probabilistic framework offers a promising core technology for robust intelligent systems, which are able to perceive, learn and interact with people and their environments

Memory and mental time travel in humans and social robots.

From neuroscience, brain imaging and the psychology of memory, we are beginning to assemble an integrated theory of the brain subsystems and pathways that allow the compression, storage and reconstruction of memories for past events and their use in contextualizing the present and reasoning about the future-mental time travel (MTT). Using computational models, embedded in humanoid robots, we are seeking to test the sufficiency of this theoretical account and to evaluate the usefulness of brain-inspired memory systems for social robots. In this contribution, we describe the use of machine learning techniques-Gaussian process latent variable models-to build a multimodal memory system for the iCub humanoid robot and summarize results of the deployment of this system for human-robot interaction. We also outline the further steps required to create a more complete robotic implementation of human-like autobiographical memory and MTT. We propose that generative memory models, such as those that form the core of our robot memory system, can provide a solution to the symbol grounding problem in embodied artificial intelligence. This article is part of the theme issue 'From social brains to social robots: applying neurocognitive insights to human-robot interaction'.Funding. The preparation of this chapter was supported by funding from the EU Seventh Framework Programme as part of the projects Experimental Functional Android Assistant (EFAA, FP7-ICT-270490) and What You Say Is What You Did (WYSIWYD, FP7-ICT-612139) and by the EU H2020 Programme as part of the Human Brain Project (HBP-SGA1, 720270; HBP-SGA2, 785907). Acknowledgements. The authors are grateful to Paul Verschure, Peter Dominey, Giorgio Metta, Yiannis Demiris and the other members of the WYSIWYD and EFAA consortia; to members of the HBP EPISENSE group; and to our colleagues at the University of Sheffield who have helped us to develop memory systems for the iCub, particularly Luke Boorman, Harry Jackson and Matthew Evans. The Sheffield iCub was purchased with the support of the UK Engineering and Physical Sciences Research Council (EPSRC)

Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots

Cataloged from PDF version of article.We report strong exciton migration with an efficiency of 83.3% from a violet-emitting epitaxial quantum well (QW) to an energy gradient colloidal construct of layered green-and red-emitting nanocrystal quantum dots (NQDs) at room temperature, enabled by the interplay between the exciton population and the depopulation of states in the optical near field. Based on the density matrix formalization of near-field interactions, we theoretically model and demonstrate that the energy gradient significantly boosts the QW-NQDs exciton transfer rate compared to using mono-dispersed NQDs, which is in agreement with the observed experimental results. (C) 2012 American Institute of Physics

Proper motions of the HH1 jet

We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of $\sim 20$~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in $\sim 450$~yr and at a distance of $\sim 80"$ from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

Making the transition to services in the animal health industry

The objective of this paper is to explore the steps and practices involved in the management of the shift to services in the context of the animal health industry. Research was carried on a leading animal health company, comparing and contrasting the transition to services between two of its most important regions. The research demonstrates that the delivery journey of the sales force lies at the core of the service transition, and it has expanded the servitization theory by unfolding the two fundamental processes that organizations experience in the transition to services. These are: the service development strategy; and the sales force delivery. This is the first research to explain the changes in “the sales force delivery” process in selling services as opposed to products. The best practices required to make the shift to services include leveraging customers’ experience, implementing service value and benefits, and building an integrated service team

Application of lca methodology to the production of strawberry on substrates with peat and sediments from ports

The Life Cycle Assessment (LCA) methodology was applied to identify the potential environmental impact of dredged sediments used as growing media for food crops. The dredged sediments used came from Livorno port and were previously phytoremediated. For the assay, strawberry plants (Fragaria x ananassa Duch vr. ‘San Andreas’) were used. The plants were cultivated on three different substrates (100% peat, 100% dredged sediment and 50% mix peat/sediment) to identify the real impact of the culture media on the growing process. LCA was calculated and analyzed according to ISO 14040:2006 by SimaPro software. ReCipe Midpoint (E) V1.13/Europe Recipe E method was applied. One kilogram of produced strawberry, for each crop media tested, was defined as the functional unit. Eighteen impact categories were selected where Marine Eutrophication (ME), Human Toxicity (HT) and Freshwater Ecotoxicity (FET) were identified as relevant impact categories. The LCA results showed an increase in the environmental impact of strawberry cultivation using 100% sediment against 100% peat, due to the decrease in fruit production caused by the sediment. Nevertheless, the decrease in the environmental impact and the fruit production increase identified when the sediment is used mixed (<50%) with other substrates. The appropriate use of these substrates would be justified within the context of the circular economy