Optimal preliminary design of variable section beams criterion

The present paper discusses about optimal shape solution for a non-prismatic planar beam. The proposed model is based on the standard Timoshenko kinematics hypothesis (i.e., planar cross-section remains planar in consequence of a deformation, but it is able to rotate with respect to the beam center-line). The analytical solution for this type of beam is thus used to obtain deformations and stresses of the beam, under different constraints, when load is assumed as the sum of a generic external variable vertical one and the self-weight. The solution is obtained by numerical integration of the beam equation and constraints are posed both on deflection and maximum stress under the hypothesis of an ideal material. The section variability is, thus, described assuming a rectangular cross section with constant base and variable height which can be described in general with a trigonometric series. Other types of empty functions could also be analyzed in order to find the best strategy to get the optimal solution. Optimization is thus performed by minimizing the beam volume considering the effects of non-prismatic geometry on the beam behavior. Finally, several analytical and numerical solutions are compared with results existing in literature, evaluating the solutions’ sensibility to some key parameters like beam span, material density, maximum allowable stress and load distribution. In conclusion, the study finds a critical threshold in terms of emptying function beyond which it is not possible to neglect the arch effect and the curvature of the actual axis for every different case study described in this work. In order to achieve this goal, the relevance of beam span, emptying function level and maximum allowable stress are investigated

Sessile droplet with negative line tension

Abstract: We study the local stability of a sessile droplet with non-vanishing line tension along the contact line, where three phases are in equilibrium. We confirm Widom\u27s results (B. Widom, Line tension and the shape of a sessile drop. J. Chem. Phys. 99 (1995), 2803-2806.) on the local stability of a droplet with positive line tension in a larger class of perturbations. When the line tension is negative, although equilibria would be unstable against modes that make the contact line wigglier and wigglier, the length over which the oscillations of destabilizing modes are effective can become too short compared ti the natural cut-off length given by the ratio between the line and the surface tensions of the droplet. Thus, provided that the line tension strength is not too large, conditionally stable equilibria exist, even when the line tension is negative

Higher correlations, universal distributions and finite size scaling in the field theory of depinning

Recently we constructed a renormalizable field theory up to two loops for the quasi-static depinning of elastic manifolds in a disordered environment. Here we explore further properties of the theory. We show how higher correlation functions of the displacement field can be computed. Drastic simplifications occur, unveiling much simpler diagrammatic rules than anticipated. This is applied to the universal scaled width-distribution. The expansion in d=4-epsilon predicts that the scaled distribution coincides to the lowest orders with the one for a Gaussian theory with propagator G(q)=1/q^(d+2 \zeta), zeta being the roughness exponent. The deviations from this Gaussian result are small and involve higher correlation functions, which are computed here for different boundary conditions. Other universal quantities are defined and evaluated: We perform a general analysis of the stability of the fixed point. We find that the correction-to-scaling exponent is omega=-epsilon and not -epsilon/3 as used in the analysis of some simulations. A more detailed study of the upper critical dimension is given, where the roughness of interfaces grows as a power of a logarithm instead of a pure power.Comment: 15 pages revtex4. See also preceding article cond-mat/030146

Sensitivity and uncertainty analysis of a plant-wide model for carbon and energy footprint of wastewater treatment plants

This paper presents the sensitivity and uncertainty analysis of a mathematical model for Greenhouse gas (GHG) and energy consumption assessment from wastewater treatment plants (WWTPs). The model is able to simultaneously describe the main biological and physical-chemical processes in a WWTP. Specifically, the mathematical model includes the main processes of the water and sludge lines influencing the methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) emissions. Further, the process energy demand and the energy recovery are also taken into account. The main objective of this paper is to analyze the key factors and sources of uncertainty influencing GHG emissions from WWTP at a plant-wide scale. The results show that influent fractionation has an important role on direct and indirect GHGs production and emission. Moreover, model factors related to the aerobic biomass growth show a relevant influence on GHGs in terms of power requirements. Thus, a good WWTP design and management aimed at limiting the GHG emission should carefully take into account the aeration system model to reduce GHG emission associated with electrical power demand. Also, the N2O emission associated with the effluent has the highest relative uncertainty bandwidth (1.7), suggesting one more need for a mechanistic model for N2O production in biological treatment

Two-parameter quantum general linear supergroups

The universal R-matrix of two-parameter quantum general linear supergroups is computed explicitly based on the RTT realization of Faddeev--Reshetikhin--Takhtajan.Comment: v1: 14 pages. v2: published version, 9 pages, title changed and the section on central extension remove

Enhanced Multi-Strategy Particle Swarm Optimization for Constrained Problems with an Evolutionary-Strategies-Based Unfeasible Local Search Operator

Nowadays, optimization problems are solved through meta-heuristic algorithms based on stochastic search approaches borrowed from mimicking natural phenomena. Notwithstanding their successful capability to handle complex problems, the No-Free Lunch Theorem by Wolpert and Macready (1997) states that there is no ideal algorithm to deal with any kind of problem. This issue arises because of the nature of these algorithms that are not properly mathematics-based, and the convergence is not ensured. In the present study, a variant of the well-known swarm-based algorithm, the Particle Swarm Optimization (PSO), is developed to solve constrained problems with a different approach to the classical penalty function technique. State-of-art improvements and suggestions are also adopted in the current implementation (inertia weight, neighbourhood). Furthermore, a new local search operator has been implemented to help localize the feasible region in challenging optimization problems. This operator is based on hybridization with another milestone meta-heuristic algorithm, the Evolutionary Strategy (ES). The self-adaptive variant has been adopted because of its advantage of not requiring any other arbitrary parameter to be tuned. This approach automatically determines the parameters’ values that govern the Evolutionary Strategy simultaneously during the optimization process. This enhanced multi-strategy PSO is eventually tested on some benchmark constrained numerical problems from the literature. The obtained results are compared in terms of the optimal solutions with two other PSO implementations, which rely on a classic penalty function approach as a constraint-handling method

Representations of the quantum matrix algebra Mq,p(2)M_{q,p}(2)

It is shown that the finite dimensional irreducible representaions of the quantum matrix algebra $M_{ q,p}(2)$ ( the coordinate ring of $GL_{q,p}(2)$) exist only when both q and p are roots of unity. In this case th e space of states has either the topology of a torus or a cylinder which may be thought of as generalizations of cyclic representations.Comment: 20 page

Width distribution of contact lines on a disordered substrate

We have studied the roughness of a contact line of a liquid meniscus on a disordered substrate by measuring its width distribution. The comparison between the measured width distribution and the width distribution calculated in previous works, extended here to the case of open boundary conditions, confirms that the Joanny-de Gennes model is not sufficient to describe the dynamics of contact lines at the depinning threshold. This conclusion is in agreement with recent measurements which determine the roughness exponent by extrapolation to large system sizes.Comment: 4 pages, 3 figure

The Impact of Wine Tourism Involvement on Winery Owners' Identity Processes

This is an Accepted Manuscript of an article published by Taylor & Francis in Tourism Planning & Development on 20/02/2020, available online: doi: https://doi.org/10.1080/21568316.2020.1730945This paper examines how involvement in wine tourism has affected winery owners’ identity processes. Using Breakwell’s Identity Process Theory (IPT) as a conceptual framework, we investigate the extent to which place is a part of winery owners’ self-identities, thereby giving them senses of belonging, distinctiveness, continuity, and self-esteem. Simultaneously, we find that these senses and feelings influence winery owners’ perceptions of the benefits and dis-benefits of wine tourism development in their region. We also discover how personal involvement in tourism can strengthen or threaten winery owners’ identities and thereby affect their support or otherwise for wine tourism. Empirical evidence is provided via a sample of twenty-eight winery owners in Langhe, Italy, who have recently engaged in various tourism-related activities due to the continuous development of the local tourism industry. Our research recognises that place is an integral part of the identity process