1,720,999 research outputs found
Planning actions in autism
No full textIt has been suggested that the deficit in understanding others’ intention in autism depends on a malfunctioning of the mirror system. This malfunction could be due either to a deficit of the basic mirror mechanism or to a disorganization of chained action organization on which the mirror understanding of others’ intention is based. Here we tested this last hypothesis investigating the kinematics of intentional actions. Children with autism and typically developing children (TD) were asked to execute two actions consisting each of three motor acts: the first was identical in both actions while the last varied for its difficulty. The result showed that, unlike in TD children, in children with autism the kinematics of the first motor act was not modulated by the task difficulty. This finding strongly supports the notion that children with autism have a deficit in chaining motor acts into a global action
Honeycomb sandwich material modelling for dynamic simulations of a crash-box for a racing carStructures Under Shock and Impact X
No full textAluminium sandwich construction has been recognized as a promising concept for structural purposes in lightweight transportation systems. The aim of the present study is to investigate, through experiment as well as numerical approaches, the energy absorbing capabilities of a thin-walled crash-box, made of sandwich material, for a racing car. The basic considered structures are panels composed by two aluminium alloy sheets and an aluminium hexagonal cells honeycomb core. Several crash tests were performed, in the conditions related to a frontal impact at the velocity of 12 m/s, in order to acquire information on the dynamic behaviour of the mentioned structure; during these tests the load-deformation diagram, the deceleration and the energy absorbed by the structure were measured. A finite element model is then developed using the non-linear, explicit dynamic code LS-DYNA. In order to characterize the material and to set up the numerical model, a series of strength tests were carried out on aluminium honeycomb-cored sandwich panel specimens. By means of these preliminary tests some necessary material parameters were determined. The simulation results accurately predicted the average deceleration, the specific absorbed energy and the total deformation of the specimen, but appeared to overestimate lightly the initial peak load obtained in the crash tests. Therefore the performed investigation can help to build confidence in the future possibility of using non-linear dynamic finite element code LS-DYNA for the design of sandwich primary structures subjected to crash loading, especially after a further tuning up of the models and material characteristics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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