Search results for "dynamics."

Enhanced calculation of optimal gradient programs in reversed-phase liquid chromatography

2003

Abstract The resolution of a mixture of 16 β-blockers under gradient elution was optimised using both isocratic and gradient training sets, with a reversed-phase column and acetonitrile–water eluents. Error theory was applied to measure the information extracted from different gradient experimental designs. This allows checking the expected accuracy when gradient predictions exceed the initial solvent concentrations tested in the training set. This work applies the results on modelling found in a previous study [J. Chromatogr. A 1018 (2003) 169] where the performance of several retention models was compared. Enhanced retention predictions were applied to the optimisation of gradient program…

Applications of mathematical modelling to the simulation of binary perfusion chromatography

1993

Abstract A mathematical model of binary (competitive adsorption involving two components) perfusion chromatography is used to simulate and study the behavior of a binary adsorption system. The dynamic behavior of column systems (frontal analysis) is examined for different particles sizes, column fluid superficial velocities, Vf, and intraparticle fluid velocities, νp. Column systems with perfusive (νp > 0) and purely diffusive (νp = 0) adsorbent particles are studied. The results obtained from the binary system studied in this work suggest that the times at which breakthrough begins for components 1 and 2, and the dynamic (unsteady state) relative separation between components 1 and 2 obtai…

Variances as order parameter and complexity measure for random Boolean networks

2005

Several order parameters have been considered to predict and characterize the transition between ordered and disordered phases in random Boolean networks, such as the Hamming distance between replicas or the stable core, which have been successfully used. In this work, we propose a natural and clear new order parameter: the temporal variance. We compute its value analytically and compare it with the results of numerical experiments. Finally, we propose a complexity measure based on the compromise between temporal and spatial variances. This new order parameter and its related complexity measure can be easily applied to other complex systems.

Theoretical study of oligomeric alumatranes present in the chemistry of materials from micro to mesoporous molecular sieves and alumina composites

2008

Quantum chemical calculations using density functional theory have been carried out to investigate molecular precursors based on alumatranes which are one of the components with silatranes for the preparation of mesoporous aluminosilicate materials. In the same way, some oligomeric alumatranes of this study take part in chemical syntheses related to materials such as zeolites and alumina composite. Gas phase and solution equilibrium geometries of the alumatrane precursors were fully optimized at B3LYP level, modeling solvent effects using a self-consistent reaction field (SCRF). From these optimized geometries, calculations of the 1 H, 13 C and 27 Al NMR chemical shifts at GIAO/B3LYP/6-31G(…

2019

Abstract The aim of this work is to present a formulation to solve the one-dimensional Ising model using the elementary technique of mathematical induction. This formulation is physically clear and leads to the same partition function form as the transfer matrix method, which is a common subject in the introductory courses of statistical mechanics. In this way our formulation is a useful tool to complement the traditional more abstract transfer matrix method. The method can be straightforwardly generalised to other short-range chains, coupled chains and is also computationally friendly. These two approaches provide a more complete understanding of the system, and therefore our work can be o…

A regenerative braking system for internal combustion engine vehicles using supercapacitors as energy storage elements - Part 2: Simulation results

2020

Abstract In this two-part work, an electric kinetic energy recovery system (e-KERS) for internal combustion engine vehicle (ICEV) is presented and its performance evaluated through numerical simulations. The KERS proposed is based on the use of a supercapacitor as energy storage, interfaced to a brushless machine through a properly designed power converter. In Part 1, the system is described and analysed, and the mathematical model used for the simulations is presented. For each component of the KERS, the real efficiency and the power or energy limitations are adequately considered. In Part 2, the energetic and economic advantages attainable by the proposed KERS are evaluated using MATLAB S…

A regenerative braking system for internal combustion engine vehicles using supercapacitors as energy storage elements - Part 1: System analysis and …

2020

Abstract In this two-part work, an electric kinetic energy recovery system (e-KERS) for internal combustion engine vehicle (ICEV) is presented, and its performance evaluated through numerical simulations. The KERS proposed is based on the use of a supercapacitor as energy storage, interfaced to a brushless machine through a properly designed power converter. In part 1, the system is described and analysed, and the mathematical model used for the simulations is presented. For each component of the KERS, the real efficiency, and the power or energy limitations are adequately considered. In part 2, the energetic and economic advantages attainable by the proposed KERS are evaluated using MATLAB…

Towards an AMTEC-like device based on non-alkali metal for efficient, safe and reliable direct conversion of thermal to electric power

2018

Alkali Metal ThermoElectric Converters directly convert heat into electric energy and have promising applicability in the field of sustainable and renewable energy. The high theoretical efficiency, close to Carnot's cycle, the lack of moving parts, and the interesting operating temperature range drive the search for new materials able to ensure safe and reliable operation at competitive costs.The present work focuses on the design of a non-alkali metal based cell and on the fabrication of a testing device to validate the design work. The selection of a new operating fluid for the cell improves durability, reliability and safety of the device. Finally, we discuss possible applications to alr…

An Algorithm for Optimal Sizing of BESS in Smart Islands Energy Communities: the Case of Pantelleria

2021

Energy Communities (EC) are a promising solution to reduce both the carbon footprint and the impact of Renewable Energy Sources (RES) on the distribution grid. Based on a simple energy sharing principle, EC can be decisive in the next future energy transition of some problematic territories, like small islands not supplied by the main power grid. By integrating Battery Energy Storage Systems (BESS), it is possible to improve the EC performance. However, due to the still high BESSs unit prices, the goal of this work is to find the optimal size of BESSs, under various conditions, which combines the need to maximize shared energy and the possible revenue of EC actors. To set this multi-objecti…

Ray matrix analysis of anamorphic fractional Fourier systems

2006

In this work we extend the application of the ray matrix approach to analyse anamorphic fractional Fourier systems, i.e., fractional Fourier optical systems where the fractional power is different for two orthogonal directions. The application of the ray matrix approach allows for easily obtaining the properties of the optical system, and it is therefore a powerful tool to design and simplify complicated systems. For simplicity we consider fractional Fourier systems with real orders and systems without apertures. We start by presenting the analysis of some previously reported anamorphic Fourier and fractional Fourier systems, and we end by proposing a simple optical system with tunable anam…