On the Exact Solution of Non-Uniform Torsion for Beams with Axial Symmetric Cross-Section
In the traditional theory of non-uniform torsion the axial displacement field is expressed as the product of the unit twist angle and the warping function. The first one, variable along the beam axis, is obtained by a global congruence condition; the second one, instead, defined over the cross-section, is determined by solving a Neumann problem associated to the Laplace equation, as well as for the uniform torsion problem. So, as in the classical theory the warping function doesn’t punctually satisfy the first indefinite equilibrium equation, the principal aim of this work is to develop a new theory for non-uniform torsion of beams with axial symmetric cross-section, fully restrained on both ends and loaded by a constant torque, that permits to punctually satisfy the previous equation, by means of a trigonometric expansion of the axial displacement and unit twist angle functions. Furthermore, as the classical theory is generally applied with good results to the global and local analysis of ship structures, two beams having the first one an open profile, the second one a closed section, have been analyzed, in order to compare the two theories. Keywords—Non-uniform torsion, Axial symmetric cross-section, Fourier series, Helmholtz equation, FE method.
Statistical properties of bulk carrier residual strength
Time-variant residual strength of bulk carriers under corrosion wastage is investigated by Monte Carlo simulation. A new formulation of the incremental–iterative approach is presented to account for instantaneous neutral axis rotation, in case of asymmetrical damage conditions. Relevant incidence on hull girder residual strength is preliminarily studied. Hence, two main aspects are investigated: the former regards the correlation among input variables, commonly assumed as uncorrelated in classical procedures. In this respect, three correlation models are considered: no correlation, full correlation, and full correlation among variables belonging to the same group of compartments. Subsequently, a z-test is performed and the hull girder residual strength probability density functions are determined for both sagging and hogging conditions, as when correlation exists, Lindeberg–Feller Central Limit Theorem cannot be applied. Three damage scenarios are analysed, according to the last requirements of Harmonized Common Structural Rules for Bulk Carriers and Oil Tankers, assuming as reference case the bulk carrier section scheme, proposed in the last ISSC Report. Finally, the residual strength factor distribution vs. time is determined, together with relevant lower/upper bound values, with certain non-exceedance probability level, that in turn depends on correlation among corrosion wastages of all structural members.
Reality TV: The Work of Being Watched
Chapter 1 1 Between the New Medium and the Old Chapter 2 2 The Promise of the Digital Revolution Chapter 3 3 Rediscovering Reality Chapter 5 4 The Kinder, Gentler Gaze of Big Brother Chapter 6 5 Access to the Real Chapter 7 6 It's All About the Experience Chapter 8 7 Reality TV and Voyeurism Chapter 9 8 Survivor and Uncanny Capitalism Chapter 10 Bibliography