323,839 research outputs found
An Object-Oriented Program for the Dynamic Simulation of Gas Turbines
No full textAn object-oriented program for the dynamic simulation of gas turbines has been developed using Matlab-Simulink® utilities. The advantages given by the object-oriented program are the flexibility and the user-friendly interface. The components of the gas turbine are modeled as blocks that can be assembled like an engineering drawing in which the connections between two elements represent either a mechanical power transfer or a fluid transfer. In a fluid-type connection the data regarding the fluid composition, the thermodynamic properties and the fluid velocity are simultaneously transferred. A library of gas turbine components has been developed: each component appears as a block that can be placed into the drawing by means of click-and-drag operations.
In order to obtain an accurate description of the physical processes characterizing the gas turbine, the components are described by a set of non-linear algebraic equations and ordinary differential equations. Each component block is created using the graphical programming tools of Simulink, following a block diagram approach. Specific blocks have been created for the evaluation of the thermodinamic properties of the working fluids. The paper provides the description of the mathematical model adopted for the simulation and the some examples of the Matlab-Simulink formulation adopted for implementing the model. The accuracy of the program has been verified considering test cases for which experimental data are available in the public literature.
The computational times, tested for the transients of a single-shaft and a double-shaft gas turbine, resulted to be very short, even making use of a personal computer
Sull'utilità della papillotomia e della papilloplastica nelle ipertensioni biliari primitive e secondarie.
No full text
La chemioterapia loco-regionale nei tumori maligni inoperabili della mammella femminile.
No full textRisultati a distanza nel trattamento radicale del cancro della mammella con particolare riguardo al problema del linfedema.
No full textA simple model of NF-kappaB dynamics reproduces experimental observations
No full textThe mathematical modeling of the NF-κB oscillations has attracted considerable attention in recent times, but there is a lack of simple models in the literature that can capture the main features of the dynamics of this important transcription factor. For this reason we propose a simple model that summarizes the key steps of the NF-κB pathway. We show that the resulting 5-dimensional dynamical system can reproduce different phenomena observed in experiments. Our model can display smooth and spiky oscillations in the amount of nuclear NF-κB and can reproduce the variety of dynamics observed when different stimulations such as TNF-α and LPS are used. Furthermore we show that the model can be easily extended to reproduce the expression of early, intermediate and late genes upon stimulation. As a final example we show that our simple model can mimic the different transcriptional outputs observed when cells are treated with two different drugs leading to nuclear localization of NF-κB: Leptomycin B and Cycloheximide
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