2,522 research outputs found

    The future of the Italian electricity generation sector. An analysis of the possible strategic models

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    The present paper investigates the possible future evolution of the Italian power system. In particular, the generation sector is considered by analyzing its recent development, which has been pushed forward by EU regulations that support the deployment of renewables-based power plants. These radical changes will determine the restructuring of the system. It is therefore critical to try to understand which trajectories its possible evolution could take according to different market and economic conditions. To this aim, a scenario analysis was implemented in order to determine the strategic implications that the various situations can yield for generators. As a result, four strategic models are envisaged, namely Traditional Generator, Innovative Generator, Green Generator, and Energy Service Provider

    Seismic amelioration of existing reinforced concrete buildings. Strategy to optimize the amount of reinforcement for joints

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    Most of the existing Reinforced Concrete (RC) buildings in Italy were built according to obsolete regulations that were not enough aware of issues related to seismic design so that they need to be upgraded by pursuing either amelioration or full seismic rehabilitation. In doing that, the first step is to figure out what is, based on the results of the initial analysis of the structure in its ante-operam version, the best overall dissipative mechanism that could be ob-tained by a number of suitable and economically convenient local interventions. The choice of the overall dissipative mechanism strongly affects the amount of reinforcement to be adopted for the beam-column joints. For new buildings, the current adopted capacity design philosophy pursues an overall beam-sway mechanism in which plastic hinges first form in beams and at last at the base of the columns. On the contrary,for existing ones, often very irregular and gravity-load-dominated, pursuing such overall mechanism may result either uneconomic or even extremely difficult to implement due to the amount of reinforcement to be inserted in the joints. In such cases, an overall dissipative mechanism allowing, at some extent, columns flex-ural plasticizationshould be accepted and clearly identified in advance. Anyway,such ap-proach needs to be addressed properly in order to avoid the formation of column-sways at one story only that would result very dangerous due to the excessive demand of plastic rotations on the resulting hinges. This paper presents two simple models that may help the designer in deal-ing with the operations above. The formeris a model that allows to understand if, given the existing RC building case-study, either the beam-sway or a hybrid beam-column-sway mecha-nism should be conveniently pursued during the design of the retrofitting intervention. The lat-ter isa model that allows to design a hybrid beam-column-sway overall mechanism involving a suitable number of stories such as to guarantee a uniform and reasonable demand of plastic rotations in the involved columns

    Metabolic Algorithm with Time-varying Reaction Maps

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    A symbolic-based approach to modelling biochemical processes and cellular dynamics is likely to turn useful in computational biology, where attempts to represent the cell as a huge, complex dynamic system must trade with the linguistic nature of the DNA and the individual behavior of the organelles living within. The early version of the metabolic algorithm gave a first answer to the problem of representing oscillatory biological phenomena, so far being treated with traditional (differential) mathematical tools, in terms of rewriting systems. We are now working on a further version of this algorithm, in which the rule application is tuned by reaction maps depending on the specific phenomenon under consideration. Successful simulations of the Brusselator, the Lotka-Volterra population dynamics and the PKC activation foster potential applications of the algorithm in systems biology

    Enhancement of heat transfer and entropy generation analysis of nanofluids turbulent convection flow in square section tubes

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    In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated. The mixture model is employed to simulate the nanofluid flow and the investigation is accomplished for particles size equal to 38 nm

    Foliar Applications with SUNRED® Biostimulant Advance and Uniform Fruit Ripening in Orange and Olive

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    This study evaluated the effect of foliar biostimulants on fruit quality of adult 'Valencia' orange and 'Biancolilla' olive trees. Half of the selected orange and olive trees were sprayed twice before harvest with the SUNRED® commercial mix containing phenylalanine, methionine, mono-saccharides and oxylipins from plant extracts as well as potassium salts and urea. Orange and olive yields and fruit quality were measured at harvest, and fruit peel color was determined by digital image analysis. Phenolic and sensory profiles were also determined in the olive oil. In orange, the foliar spray increased TSS:acid ratio and peel color uniformity, while in olive, it increased peel color uniformity, oleocanthal, and 3,4-DHPEA-EDA and decreased oil spiciness. The results of this study suggest that foliar sprays with the SUNRED® biostimulant in pre-harvest may improve fruit quality of 'Valencia' orange and 'Biancolilla' olive by advancing and uniforming fruit ripening

    A FULLY IMPLICIT MATERIAL RESPONSE CODE WITH ABLATION AND PYROLYSIS FOR SIMULATION OF THERMAL PROTECTION SYSTEMS

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    The purpose of this paper is to introduce and describe a 2-D fully implicit numerical simulation tool capable of evaluating the behaviour of an ablative charring thermal protection system during atmospheric entry. In particular, the computational tool can model the heat transfer inside a solid porous material and the decomposition of the latter, pyrolysis gas density, pressure and speed distributions and surface recession. The governing equations are fully coupled and are integrated using a time-implicit scheme. The grid can contract to simulate the recession phenomenon and the recession rate can be evaluated using different ablation models, depending on the problem and on the available data. Spatial and temporal convergence tests demonstrated that the tool is second order accurate in space and time and comparisons with available numerical results are shown here for code verification

    Linking Bistable Dynamics to Metabolic P Systems

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    Bistability, or more generally multistability, is an important recurring theme in biological systems. In particular, the discovery of bistability in signal pathways of genetic networks, prompts strong interest in understanding both the design and function of these networks. Therefore, modelling these systems is crucial to understand their behaviors, and also to analyze and identify characteristics that would otherwise be di cult to realize. Although di erent classes of models have been used to study bistable dynamics, there is a lag in the development of models for bistable systems starting from experimental data. This is due to the lack of detailed knowledge of biochemical reactions and kinetic rates. In this work, we propose a procedure to develop, starting from observed dynamics, Metabolic P models for multistable processes. As a case study, a mathematical model of the Schl ogel's dynamics, which represents an example of a chemical reaction system that exhibits bistability, is inferred starting from observed stochastic bistable dynamics. Since, recent experiments indicate that noise plays an important role in the switching of bistable systems, the success of this work suggests that this approach is a very promising one for studying dynamics and role of noise in biological systems, such as, for example, genetic regulatory networks

    Thermal behavior evaluation of ventilated roof under summer and winter conditions

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    One of the European Directive priorities is the development of new strategies for \u201cvery low energy buildings\u201d. In regions with high level of solar radiation, ventilation allows the cooling load during summer period and contributes to the reduction of the energy needs of buildings. The most important advantages are the reduction of the heat fluxes transmitted by the structures exposed to solar radiation, thanks to the combined effect of shading surfaces and heat removed by the air flow rate within the ventilated air gap. This paper illustrates a numerical investigation on a prototypal ventilated roof for residential use. The investigation is performed in order to evaluate thermofluidodynamic behaviors of the ventilated roof as a function of the different conditions applied on the top wall and the bottom wall of the ventilated cavity in summer and winter regimes. Different values of heat fluxes are applied on the top wall of the ventilated cavity to simulate typical summer and winter days conditions, whereas the bottom wall is assumed isothermal and different values of wall temperature are considered. The problem is solved by means of the commercial code Ansys-Fluent. Results are given in terms of temperature and velocity distributions, air velocity and temperature profiles along different longitudinal and cross sections of the ventilated layer in order to estimate differences between analyzed conditions

    RADIATION EFFECT ON TRANSIENT NATURAL CONVECTION IN VENTILATED ROOFS

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    This paper illustrates a numerical investigation on a prototypal ventilated roof for residential use, under summer and winter conditions. The roof is modeled as a single flap, due to its geometric and thermal symmetry, and it is analyzed as two-dimensional, in air flow, thanks to the commercial code Ansys-Fluent. The governing equations are given in terms of k-\uf065 turbulence model taking into account the radiation effect inside the channel. The analysis is performed in order to evaluate thermofluidodynamic behaviours of the ventilated roof, in transient regime with radiative heat transfer presence, as a function of the solar radiation applied on the top wall of the ventilated roof. The discrete transfer radiation model (DTRM) is chosen. Typical summer and winter conditions with heat transfer from the channel top wall toward the external ambient are examined. The bottom wall of the ventilated channel is simulated as isothermal, considering optimal temperature values for the internal ambient in summer and winter regimes. Results are given in terms of temperature and pressure distributions, air velocity and temperature profiles along longitudinal and cross sections of the ventilated layer, in order to estimate the differences between the various conditions. Ventilated roof configuration results significant to reach optimal thermal and fluid dynamic conditions in summer and winter regimes. In summer period, when the effect of solar radiation is more evident thanks to the convective effect within the channel, temperature values are higher and the effect of the ventilated channel is significative to reach comfort conditions. In winter, the effect of the ventilated layer is very important to reach optimal thermal and hygrometric conditions
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