One of the common failure modes of thin cylindrical shell subjected external pressure is buckling. The buckling pressure of these shell structures are dominantly affected by the geometrical imperfections present in the cylindrical shell which are very difficult to alleviate during manufacturing process. In this work, only three types of geometrical imperfection patterns are considered namely (a...

The assessment of the buckling and ultimate collapse strength is a mandatory step in limit state design ship structures. analysis ship-type stiffened panels under longitudinal compression highly affected by initial geometric imperfection. Several imperfection models are available literature. Broadly speaking, they can be categorised into deterministic probabilistic approaches. approach describe...

Perfect graphs constitute a well-studied graph class with a rich structure, reflected by many characterizations with respect to different concepts. Perfect graphs are, for instance, precisely those graphs G where the stable set polytope STAB(G) coincides with the fractional stable set polytope QSTAB(G). For all imperfect graphs G it holds that STAB(G) ⊂ QSTAB(G). It is, therefore, natural to us...

Buckling of soft matter is ubiquitous in nature and has attracted increasing interest recently. This paper studies the retractile behaviors of a spherical shell perforated by sophisticated apertures, attributed to the buckling-induced large deformation. The buckling patterns observed in experiments were reproduced in computational modeling by imposing velocity-controlled loads and eigenmode-aff...

We present results from an experimental and numerical investigation on the compression, and consequent buckling, of a slender rod constrained inside a horizontal cylinder. An experimental model system is developed to systematically study the sequence of instabilities from straight-to-sinusoidal and sinusoidal-to-helical configurations. We quantify the associated buckling loads as a function of ...

For any graph G, it is obvious that χ(G) ≥ ω(G), but whether χ(G) can be bounded from above by a function of ω(G) is not at all clear. Recall that the two numbers are equal for every induced subgraph of a perfect graph. Thus the ratio of the chromatic number to the clique number of a graph is often studied as a measure of its “imperfection”; see for example Dumitrescu and Jiang (2010) for some ...

Because of their inherent abstraction, systems ideas are not themselves sufficient for gaining scientific knowledge or solving practical problems, but they can be a source of insights into the universality of imperfection, insights which can contribute to a new scientific world view. Systems theory offers a metaphysics, or more precisely an ontology, of imperfection. Through it, we can heed Spi...

We are interested in colouring a graph G=(V, E) together with an integral weight or demand vector x=(xv : v # V) in such a way that xv colours are assigned to each node v, adjacent nodes are coloured with disjoint sets of colours, and we use as few colours as possible. Such problems arise in the design of cellular communication systems, when radio channels must be assigned to transmitters to sa...

This paper proposes a machine learning based methodology for predicting the buckling response of tubular structures. An extensive dataset force-time curves is generated using calibrated finite element model within parametric space where highly non-linear. Based on fully connected neural network template, hyper-parameters are determined and resulting evaluated separate test set, with regard to m...