Fault tolerant control using Gaussian processes and model predictive control

Essential ingredients for fault-tolerant control are the ability to represent system behaviour following the occurrence of a fault, and the ability to exploit this representation for deciding control actions. Gaussian processes seem to be very promising candidates for the first of these, and model predictive control has a proven capability for the second. We therefore propose to use the two together to obtain fault-tolerant control functionality. Our proposal is illustrated by several reasonably realistic examples drawn from flight control. © 2013 IEEE.

When is a symmetric body-hinge structure isostatic?

A symmetry-extended mobility rule is formulated for body-hinge frameworks and used to derive necessary symmetry conditions for isostatic (statically and kinematically indeterminate) frameworks. Constructions for symmetric body-hinge frameworks with an isostatic scalar count are reported, and symmetry counts are used to examine these structures for hidden, symmetry-detectable mechanisms. Frameworks of this type may serve as examples for exploration of a symmetry extension of the (now proven) 'molecular conjecture'. © 2014 Elsevier Ltd. All rights reserved.

Masonry response to tunnelling: a sensitivity study on the effect of cracking and building weight

Predicting damage to masonry structures due to tunnelling-induced ground movements remains a challenge for practising design engineers. Useful simplified procedures exist, but more detailed analysis has the potential to improve these procedures. This paper considers the use of finite element modelling, including non-linear constitutive laws for the soil and the structure, to simulate damage to a simple masonry structure subjected to tunnelling in sand. The numerical model is validated through comparison with the results of a series of centrifuge tests and used to perform a sensitivity study on the effect of building weight and masonry damage on the structural response. Results show a direct correlation between the weight of the structure, normalised to the relative stiffness between the structure and the soil, and the modification of the settlement profile. By including a cracking model for the masonry, the reduction in structural stiffness caused by progressive masonry damage is also proven to affect the building deflection.

Climbing vertical terrains with a self-contained robot

Vertical climbing on a variety of flat surfaces with a single robot has been previously demonstrated using vacuum suction, electrostatic adhesion, and biologically inspired approaches, etc. These methods generally have a low attachment strength, and it is not clear whether they can provide satisfactory attachment on vertical terrains with richer 3D features. Recent development of a climbing technology based on hot melt adhesives (HMAs) has shown its advantage with a high attachment strength through thermal bonding and viability to any solid surfaces. However, its feasibility for vertical climbing has only been proven on flat surfaces and with external energy supplies. This paper provides quantitative measurements for vertical climbing performance on five types of surfaces and terrains with a self-contained robot exploiting HMAs. We show that robust vertical climbing on multiple terrains can be achieved with reliable high-strength attachment. © 2012 IEEE.

High performance transistors based on the controlled growth of triisopropylsilylethynyl-pentacene crystals via non-isotropic solvent evaporation

Triisopropylsilylethynyl-pentacene (TIPS-PEN) has proven to be one of the most promising small molecules in the field of molecular electronics, due to its unique features in terms of stability, performance and ease of processing. Among a wide variety of well-established techniques for the deposition of TIPS-PEN, blade-metered methods have recently gained great interest towards the formation of uniform crystalline films over a large area. Following this rationale, we herein designed a versatile approach based on blade-coating, which overcomes the problem of anisotropic crystal formation by manipulating the solvent evaporation behaviour, in a way that brings about a preferential degree of crystal orientation. The applicability of this method was evaluated by fabricating field-effect transistors on glass as well as on silicon dioxide/silicon (SiO2/Si) substrates. Interestingly, in an attempt to improve the rheological and wetting behaviour of the liquid films on the SiO2/Si substrates, we introduced a polymeric interlayer of polystyrene (PS) or polymethylmethacrylate (PMMA) which concurrently acts as passivation and crystallization assisting layer. In this case, the synergistic effects of the highly-ordered crystalline structure and the oxide surface modification were thoroughly investigated. The overall performance of the fabricated devices revealed excellent electrical characteristics, with high saturation mobilities up to 0.72 cm2 V-1 s-1 (on glass with polymeric dielectric), on/off current ratio >104 and low threshold voltage values (<-5 V). This journal is © the Partner Organisations 2014.