Abstract sentence representations in 3-year-olds: Evidence from language production and comprehension

We use syntactic priming to test the abstractness of the sentence representations of young 3-year-olds (35-42 months). In describing pictures with inanimate participants, 18 children primed with passives produced more passives (11 with a strict scoring scheme, 16 with lax scoring) than did 18 children primed with actives (2 on either scheme) or 12 children who received no priming (0). Priming was comparable to that reported for older children and adults. Comprehension of reversible passives with animate participants before and after priming was above chance but did not improve as a result of priming. Young 3-year-olds represent sentences abstractly, have syntactic representations for noun, verb, "surface subject", and "surface object", have semantic representations for "agent" and "patient", and flexibly map the relation between syntax and semantics. Taken together with research on syntactic categories in 2-year-olds, our results provide empirical support for continuity in language acquisition

Behavior of elastomeric seismic isolators varying rubber material and pad thickness: A numerical insight

A numerical approach for the determination of (a) the shear behavior under large displacements and (b) the compression elastic modulus of common parallelepiped elastomeric isolators is presented. Particular attention is devoted to the role played by the material used for the rubber pads and their thickness. For them, an experimental data fitting by means of both a nine constants Mooney-Rivlin and a five constants exponential law is utilized, within a Finite Element discretization of the isolator. Having at disposal a few experimental stretch-stress data points for each rubber compound in uniaxial tension, a cubic Bezier spline approach is firstly utilized, to generate numerically a large number of metadata containing the original experimental ones. Then, respectively the nine Mooney-Rivlin and five exponential law constitutive parameters are estimated through a least square approach. Once assessed the models, a full scale rectangular seismic isolator is analyzed when subjected to horizontal actions and normal compression, in order to provide estimates of the initial stiffness and the overall behavior of the isolator undergoing large deformations, using both models and for all the compounds considered. It is found that the global behavior may depend significantly on the material hypothesis assumed to model rubber and on pads thickness

A review of morphing aircraft

Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is short for metamorphose: however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title “shape morphing”. Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep and chord), out-of-plane transformation (twist, dihedral/gull, spanwise bending) and airfoil adjustment (camber and thickness).Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity or weight, although in certain circumstances these were overcome by system level benefits. The current trend for highly efficient and “green” aircraft makes such compromises less acceptable, calling for innovative morphing designs able to provide more benefits and fewer drawbacks. Recent developments in “smart” materials may overcome the limitations and enhance the benefits from existing design solutions. The challenge is to design a structure that is capable of withstanding the prescribed loads, but is also able to change its shape: ideally there should be no distinction between the structure and the actuation system. The blending of morphing and smart structures in an integrated approach requires multi-disciplinary thinking from the early development, which significantly increases the overall complexity, even at the preliminary design stage. Morphing is a promising enabling technology for future, next generation aircraft. However, manufacturers and end users are still too skeptical of the benefits to adopt morphing in the near future. Many developed concepts have a technology readiness level that is still very low. The recent explosive growth of satellite services means that UAVs are the technology of choice for many investigations on wing morphing.This paper presents a review of the state of the art on morphing aircraft and focuses on structural, shape changing morphing concepts for both fixed and rotary wings, with particular reference to active systems. Inflatable solutions have been not considered, and skin issues and challenges are not discussed in detail. Although many interesting concepts have been synthesized, few have progressed to wing tunnel testing, and even fewer have flown. Furthermore, any successful wing morphing system must overcome the weight penalty due to the additional actuation systems.<br/