Predictive control of a solar air conditioning plant with simultaneous identification

This paper presents the application of a predictive controller with simultaneous identification to a solar air conditioning plant. The time varying nature of the process makes necessary an adjustment of the controller parameters to the varying operational conditions. The main novelty with respect to classic adaptive MPC scheme is to penalize the identification error in the cost function used for control. The behaviour of the controller is illustrated by simulations and experimental results. The integration of identification and control avoids the tedious identification procedure that is necessary before the start-up of any predictive controller. This new adaptive MPC scheme shows its effectiveness in controlling the outlet temperature in the solar thermal plant.Ministerio de Ciencia y Tecnología DPI2004-07444-C04-0

Predictive control of an olive oil mill with multi-objective prioritization

INTERNATIONAL FEDERATION OF AUTOMATIC CONTROL. WORLD CONGRESS (15.2002.BARCELONA)This paper presents a multi-objective controller applied to an olive oil mill. The practical experience using a Generalized Predictive Controller (GPC) in the real plant showed the necessity of including objectives, with different priorities, in the process control. The analysis demonstrates that GPC with prioritization objectives can control the process and fulfill the specified operational conditions. The results are illustrated with some simulations that compare the traditional GPC to the multi-objective one.Comisión Europea 1FD97-0836 (FEDER

Scalable Approach to Uncertainty Quantification and Robust Design of Interconnected Dynamical Systems

Development of robust dynamical systems and networks such as autonomous aircraft systems capable of accomplishing complex missions faces challenges due to the dynamically evolving uncertainties coming from model uncertainties, necessity to operate in a hostile cluttered urban environment, and the distributed and dynamic nature of the communication and computation resources. Model-based robust design is difficult because of the complexity of the hybrid dynamic models including continuous vehicle dynamics, the discrete models of computations and communications, and the size of the problem. We will overview recent advances in methodology and tools to model, analyze, and design robust autonomous aerospace systems operating in uncertain environment, with stress on efficient uncertainty quantification and robust design using the case studies of the mission including model-based target tracking and search, and trajectory planning in uncertain urban environment. To show that the methodology is generally applicable to uncertain dynamical systems, we will also show examples of application of the new methods to efficient uncertainty quantification of energy usage in buildings, and stability assessment of interconnected power networks

Non-linear predictive control for manufacturing and robotic applications

The paper discusses predictive control algorithms in the context of applications to robotics and manufacturing systems. Special features of such systems, as compared to traditional process control applications, require that the algorithms are capable of dealing with faster dynamics, more significant unstabilities and more significant contribution of non-linearities to the system performance. The paper presents the general framework for state-space design of predictive algorithms. Linear algorithms are introduced first, then, the attention moves to non-linear systems. Methods of predictive control are presented which are based on the state-dependent state space system description. Those are illustrated on examples of rather difficult mechanical systems

Constrained generalized predictive control of battery charging process based on a coupled thermoelectric model

Battery temperature is a primary factor affecting the battery performance, and suitable battery temperature control in particular internal temperature control can not only guarantee battery safety but also improve its efficiency. This is however challenging as current controller designs for battery charging have no mechanisms to incorporate such information. This paper proposes a novel battery charging control strategy which applies the constrained generalized predictive control (GPC) to charge a LiFePO₄ battery based on a newly developed coupled thermoelectric model. The control target primarily aims to maintain the battery cell internal temperature within a desirable range while delivering fast charging. To achieve this, the coupled thermoelectric model is firstly introduced to capture the battery behaviours in particular SOC and internal temperature which are not directly measurable in practice. Then a controlled auto-regressive integrated moving average (CARIMA) model whose parameters are identified by the recursive least squares (RLS) algorithm is developed as an online self-tuning predictive model for a GPC controller. Then the constrained generalized predictive controller is developed to control the charging current. Experiment results confirm the effectiveness of the proposed control strategy. Further, the best region of heat dissipation rate and proper internal temperature set-points are also investigated and analysed

Polyaniline membranes for use in organic solvent nanofiltration

Imperial Users onl

Organosiloxane working fluids for the liquid droplet radiator

Siloxane-based working fluids for advanced space radiators requiring direct fluid exposure to the space environment are evaluated. Isolation of five candidate fluids by vacuum distillation from existing siloxane polymers is discussed. The five fluids recovered include a polydimethylsiloxane, three phenyl-containing siloxanes, and a methylhexylsiloxane. Vapor pressures and viscosities for the five fluids are reported over the temperature range of 250 to 400 K. Use of thermal-gravimetric analysis to reliably estimate vapor pressures of 10 to the -8 power Pascals is described. Polydimethylsiloxane (PDMS) and polymethylphenylsiloxane (PMPS) are selected from the five candidate fluids based on favorable vapor pressure and viscosity, as well as perceived stability in low-Earth orbit environments. Characterization of these fluids by infrared spectroscopy, Si-29 NMR, gel-permeation chromatography, and liquid chromatography is presented. Both fluids consist of narrow molecular weight distributions, with average molecular weights of about 2500 for PDMS and 1300 for PMPS

Data-based mechanistic modelling, forecasting, and control.

This article briefly reviews the main aspects of the generic data based mechanistic (DBM) approach to modeling stochastic dynamic systems and shown how it is being applied to the analysis, forecasting, and control of environmental and agricultural systems. The advantages of this inductive approach to modeling lie in its wide range of applicability. It can be used to model linear, nonstationary, and nonlinear stochastic systems, and its exploitation of recursive estimation means that the modeling results are useful for both online and offline applications. To demonstrate the practical utility of the various methodological tools that underpin the DBM approach, the article also outlines several typical, practical examples in the area of environmental and agricultural systems analysis, where DBM models have formed the basis for simulation model reduction, control system design, and forecastin

Prediction of Liquid Crystalline Content and Molecular Structures Present in Carbonaceous Pitches

ABSTRACT Previous research at Clemson has shown that multistage, packed column, supercritical extraction (also called dense-gas extraction, or DGE) of petroleum pitches is a promising technique for the production of carbonaceous precursors that can be processed into a variety of carbon products, including activated carbons and high thermal conductivity carbon fibers. As the existence (or lack thereof) of a liquid crystalline phase, or mesophase, plays a key role in establishing the suitability of a potential precursor material for a given application, we developed the SAFT-LC (liquid crystal) equation of state by combining Maier-Saupe theory for multicomponent mixtures with the SAFT equation. SAFT-LC was used with some success to predict the effect of temperature and pressure, as well as pitch and solvent composition, on the formation of mesophase at both supercritical and ambient conditions. Unfortunately, the lack of information about the actual molecular structures present in petroleum pitch hindered the development of an appropriate set of pure-component parameters for use with SAFT-LC. Thus, the second half of this dissertation focused on structural characterization. Previous efforts to characterize the molecular structures of the major species present in pitches have been limited by an inability to fractionate the pitch into cuts of narrow molecular weight (mol wt). However, by using DGE followed by preparatory-scale gel permeation chromatography (prep-scale GPC), we are now able to fractionate petroleum pitch into its constituent oligomers. Subsequent analytical characterization of these oligomers using high-performance liquid chromatography with photodiode array detection (HPLC/PDA), matrix-assisted, laser desorption and ionization, time-of-flight mass spectrometry (MALDI), MALDI-post source decay (PSD), and UV-Visible spectrophotometry (UV-Vis) has determined that M-50 monomer is primarily comprised of benzenoid, polycyclic aromatic hydrocarbon (PAH) \u27backbones\u27 (the most prevalent of which are pyrene, chrysene, benz[a]anthracene, triphenylene, benzo[a]pyrene, benzo[e]pyrene, and benzo[ghi]perylene), substituted with from 0 to 4 alkyl (primarily methyl) groups. The most prevalent dimers are formed from the condensation reaction of two of the most prevalent monomer units, such that four hydrogens are lost and a five-membered, connecting ring is formed to create a fluoranthenoid PAH. For trimers and tetramers, MALDI, UV-Vis, and transmission FT-IR results are all consistent with the linkage of the most prevalent lower-order oligomeric units via a single, five-membered ring. Thus, the body of evidence indicates that the highly PAH-condensed structure previously proposed for such pitches does not exist