1,721,389 research outputs found
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
Effect of operating temperature on aged single lap bonded joints
Full text linkIn recent decades, designers have increasingly focused on the stability of assemblies in composite materials over time, particularly when used in structural applications. The use of structural adhesives allows for realising assemblies without mechanical fasteners. In fact, bonding is an assembly technique that prevent corrosion, ensures uniform stresses in the joint, and grows the specific resistance of the assembly. The knowledge of the behaviour of bonded joint is necessary to ensure the reliability of this technique over time, especially in aggressive environments. The aim of this work consists in investigating the combined effect of hydrothermal ageing and temperature test on the lap shear strength of single lap joints realised in CFRP. The results showed a higher influence of the ageing on paste adhesive compared to film adhesive. However, the ageing, combined with the operating temperature, played a fundamental role on the shear strength of the bonded joints
Lightweight structures: An innovative method to uniform the thickness of metal sheets by patchwork blanks
No full textMetal sheet forming is widely used in industrial field. Generally, the use of patchwork banks allows the manufacturing of a more uniform thickness of the formed parts. Often, they are obtained using welding techniques: in these cases, distortions and localized metallurgical transformations could have detrimental effects on the mechanical performance. Moreover, it is not possible to weld very thin patches. In this paper, an innovative approach based on bonded patches has been developed and investigated. In this manner, it is possible to adopt thinner patches, doing away with the problems arising from the welding process. Experimental tests showed the potentiality of using adhesives in forming processes to influence the thickness distribution. Moreover, the commercial code PAM-STAMP has been used for modelling the forming process. In this way, the effects of the thickness of the patch and the friction conditions on the strain state generated on the patchwork blanks have been investigated
Study of autoclave process to manufacture thermoplastic composites constituted by PP/flax fibers
No full textAutoclave processes are widely used from industries that produce thermoset polymer composite parts. However, these materials show sustainability issues as they are non-recyclable and produced by energy-intensive processes. The use of thermoplastic matrices reinforced with natural fibers can solve these problems; however the optimal use of this material is linked to the knowledge of the forming parameters. In this work, starting from semipreg sheets, the autoclave forming process for parts in flax woven and polypropylene is studied and developed: it represents a fundamental step to develop the use of these new eco-friendly materials starting from the wellestablished industrial knowledge, not only in terms of environmental sustainability, but also economic and social sustainability. First, working temperatures were determined by DSC and TGA; while optimal forming pressure were determined by ILSS tests
Trattamento al plasma freddo per il miglioramento della bagnabilita' dei polimeri a cristalli liquidi
No full textAlternating-time temporal logics with linear past
No full textWe investigate the succinctness gap between two known equally-expressive and different linear-past extensions of standard ATL⁎. We establish by formal non-trivial arguments that the ‘memoryful’ linear-past extension (the history leading to the current state is taken into account) can be exponentially more succinct than the standard ‘local’ linear-past extension (the history leading to the current state is forgotten). As a second contribution, we consider the ATL-like fragment, denoted ATLlp, of the known ‘memoryful’ linear-past extension of ATL⁎. We show that ATLlp is strictly more expressive than ATL, and interestingly, it can be exponentially more succinct than the more expressive logic ATL⁎. Moreover, we prove that both satisfiability and model-checking for the logic ATLlp are EXPTIME -complete
Hiding actions in multi-player games
No full textIn the game-Theoretic approach to reasoning about multi-Agent systems, imperfect information plays a key role. It requires that players act in accordance with the information available to them. The complexity of deciding games that have imperfect information is generally worse than those that do not have imperfect information, and is easily undecidable. In many real-life scenarios, however, we just have to deal with very restricted forms of imperfect information and limited interactions among players. In these settings, the challenge is to come up with elementary decision procedures, as we do. We study multi-player concurrent games where (i) Player0's objective is to reach a target W, and (ii) the opponents are trying to stop this but have partial observation about Player0's actions. We study the problem of deciding whether the opponents can prevent Player0 to reach W, by beating every Player0's strategy. We show, using an automata-Theoretic approach that, assuming the opponents have the same partial observation and play under uniformity, the problem is in ExpTime
Combined Finite-Discrete Element Model Simulations of Shake-Table Tests on a Full-Scale Masonry Cross Vault
No full textThis work presents the numerical simulations of shaking table tests of a full-scale masonry cross vault. The boundary conditions simulate the presence of a continuous lateral wall and of a colonnade-between-naves condition. The seismic action is applied along the longitudinal direction of the specimen, with increasing amplitude. The model used for the simulations allows for the elastic finite element modelling of masonry units and the discrete element modelling of the interfaces between them. A tension cut-off governs the interface: no tensile stress can be transmitted once this strength is exceeded. The shear response is defined by cohesion and friction: once the former is exceeded the interface reacts according to Coulomb’s behaviour. The simulations are related to the blind predictions, according to the scheduled tests, and the post-dictions, according to the actual testing sequence. The prediction model overestimates displacements and does not catch the actual crack distribution. Therefore, a post-simulation model was implemented, revising the masonry elastic modulus as well as the stiffness and boundary conditions of the supporting piers. Simulations are improved both in terms of displacement predictions and damage mechanism. Finally, the sensitivity to finite-element size, damping ratio and block discretisation was explored
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