The high efficiency of circular monocoque cylindrical shells in carrying axial loads is impaired by their extreme sensitivity to imperfections and there is an extensive body of literature that addresses this behavior. Instead of following this classical path, focused on circular cross-sections, this paper presents a novel approach that adopts optimal symmetry-breaking wavy cross-sections (wavy ...

Large crystalline molecular shells, such as some viruses and fullerenes, buckle spontaneously into icosahedra. Meanwhile multicomponent microscopic shells buckle into various polyhedra, as observed in many organelles. Although elastic theory explains one-component icosahedral faceting, the possibility of buckling into other polyhedra has not been explored. We show here that irregular and regula...

Elastic stability of ring and stringer-stiffened cylindrical shells under axial, internal and external pressures is studied using Ritz method. The stiffeners are rings, stringers and their different arrangements at the inner and outer surfaces of the shell. Critical buckling loads are obtained using Ritz method. It has been found that the cylindrical shells with outside rings are more stable th...

Zonation of organisms in soft-bottom intertidal habitats is mainly a consequence of the tidal sorting of the substrate and how benthic organisms respond to it, with predation and competition also playing a role. Although parasites are ubiquitous in these habitats and known agents of community structure, their impact on zonation is rarely considered. Here, using observational and experimental da...

In the present research, the elastic buckling of composite cross-ply elliptical cylindrical shells under axial compression is studied through finite element approach. The formulation is based on shear deformation theory and the serendipity quadrilateral eight-node element is used to study the elastic behavior of elliptical cylindrical shells. The strain-displacement relations are accurately acc...

We show that Dejean’s conjecture holds for n ≥ 27. This brings the final resolution of the conjecture by the approach of Moulin Ollagnier within range of the computationally feasible. Repetitions in words have been studied since the beginning of the previous century [14, 15]. Recently, there has been much interest in repetitions with fractional exponent [1, 3, 6, 7, 8, 10]. For rational 1 < r ≤...

This paper develops a methodology for benchmarking knowledge-based systems that practitioners may use to perform a comparative analysis of expert system shells. A program utilizing a deliberate instructional mix was found to be the most suitable and accurate way to measure the value of shells. The benchmark is intended for rule-based shells, such as CLIPS, VP-Expert and Ibis. The methodology fo...