Bamboo trusses with low cost and high ductility joints

Innovative solutions of joints for bamboo trusses are presented. Experimental tests show the performances and the high level of ductility of the proposed technique, joined with simplicity in the concept of the joints, low level of technology and low cost of all used materials. It can permit a proper dissemination and a sustainable maintenance in developing countries

Draft tube discharge fluctuation during self-sustained pressure surge: fluorescent particle image velocimetry in two-phase flow

Hydraulic machines play an increasingly important role in providing a secondary energy reserve for the integration of renewable energy sources in the existing power grid. This requires a significant extension of their usual operating range, involving the presence of cavitating flow regimes in the draft tube. At overload conditions, the self-sustained oscillation of a large cavity at the runner outlet, called vortex rope, generates violent periodic pressure pulsations. In an effort to better understand the nature of this unstable behavior and its interaction with the surrounding hydraulic and mechanical system, the flow leaving the runner is investigated by means of particle image velocimetry. The measurements are performed in the draft tube cone of a reduced scale model of a Francis turbine. A cost-effective method for the in-house production of fluorescent seeding material is developed and described, based on off-the-shelf polyamide particles and Rhodamine B dye. Velocity profiles are obtained at three streamwise positions in the draft tube cone, and the corresponding discharge variation in presence of the vortex rope is calculated. The results suggest that 5-10% of the discharge in the draft tube cone is passing inside the vortex rop

Categorie dello "spirito" nella Cina pre-buddhista

Esame del complesso insieme di nozioni che concorrono a definire la concezione dello spirito e degli spiriti nella Cina antic

Trasmetto, non creo. Percorsi tra filologia e filosofia nella letteratura cinese classica

“Trasmetto, non creo: credo negli antichi, li venero e, nel far ciò, oso paragonarmi al Venerabile Peng”. Stando al Lunyu, così Confucio definì la propria missione. Nel trasmettere si rischia, però, di “tradire”, poiché “trasmettere” significa, pur sempre, “tradurre”, ovvero adottare nuove forme per articolare le visioni normative dell’antichità. Addirittura, non solo si rischia, ma si deve tradire: in fondo, linguaggi destinati a superare i contesti che li hanno generati non possono che essere traditi. “Leggere bene” le opere cinesi antiche significa, dunque, saper cogliere incongruenze e discontinuità nelle rappresentazioni di un passato normativo e, soprattutto, valutare i condizionamenti contestuali che ne hanno determinato la trasmissione. Occorre, dunque, seguire un approccio che è, al contempo, filologico e filosofico e che non mira tanto a ricreare la purezza di un’antichità immune dalla corruzione, bensì al disvelamento delle dinamiche dell’imperfezione

Large-Eddy Simulation of a Turbulent Spray Flame Using the Flamelet Generated Manifold Approach

Abstract In order to meet the increasingly stringent regulations in terms of pollutant emissions adopted by ICAO-CAEP in last years, a redesign of aero-engine combustors has been required and, today, lean combustion technology can be considered as the most effective solution. In this context, common design tools and standard RANS predictive techniques are often not capable of properly characterizing combustors performances. Thus, computational techniques have been rapidly evolving towards an extensive use of Large-Eddy Simulation (LES) or hybrid RANS methods. This paper presents the numerical analysis of an experimental partially premixed flame fed by a dilute spray of acetone [1] , exploiting a two-phase Eulerian-Lagrangian approach combined with the Flamelet Generated Manifold (FGM) combustion model in the context of LES techniques. All simulations have been performed with thecode Ansys Fluent 15.0. A comparison both in non-reactive and reactive conditions of the obtained results with experimental data and conventional RANS solution has been realized in order to highlight the LES capabilities to give a new insight into the physics of reactive two-phase flows, particularly on the unsteady evolution of turbulent spray flames involving particles dispersion, evaporation and combustion