Modelización del cálculo de Indicadores Ambientales, a partir de sensores ópticos de alta resolución temporal a bordo de satélite

La presente tesis doctoral tiene por objeto el estudio y análisis de técnicas y modelos de obtención de parámetros biofísicos e indicadores ambientales, de manera automatizada a partir de imágenes procedentes de satélite de alta resolución temporal. En primer lugar se revisan los diferentes programas espaciales de observación del territorio, con especial atención a los que proporcionan dicha resolución. También se han revisado las metodologías y procesos que permiten la obtención de diferentes parámetros cuantitativos y documentos cualitativos, relacionados con diversos aspectos de las cubiertas terrestres, atendiendo a su adaptabilidad a las particularidades de los datos. En segundo lugar se propone un modelo de obtención de parámetros ambientales, que integra información proveniente de sensores espaciales y de otras fuentes auxiliares utilizando, en cierta medida, las metodologías presentadas en apartados anteriores y optimizando algunas de las referidas o proponiendo otras nuevas, de manera que se permita dicha obtención de manera eficiente, a partir de los datos disponibles y de forma sistemática. Tras esta revisión de metodologías y propuesta del modelo, se ha procedido a la realización de experimentos, con la finalidad de comprobar su comportamiento en diferentes casos prácticos, depurar los flujos de datos y procesos, así como establecer las situaciones que pueden afectar a los resultados. De todo ello se deducirá la evaluación del referido modelo. Los sensores considerados en este trabajo han sido MODIS, de alta resolución temporal y Thematic Mapper (TM), de media resolución espacial, por tratarse de instrumentos de referencia en la realización de estudios ambientales. También por la duración de sus correspondientes misiones de registro de datos, lo que permite realizar estudios de evolución temporal de ciertos parámetros biofísicos, durante amplios periodos de tiempo. Así mismo. es de destacar que la continuidad de los correspondientes programas parece estar asegurada. Entre los experimentos realizados, se ha ensayado una metodología para la integración de datos procedentes de ambos sensores. También se ha analizado un método de interpolación temporal que permite obtener imágenes sintéticas con la resolución espacial de TM (30 m) y la temporal de MODIS (1 día), ampliando el rango de aplicación de este último sensor. Asimismo, se han analizado algunos de los factores que afectan a los datos registrados, tal como la geometría de la toma de los mismos y los episodios de precipitación, los cuales alteran los resultados obtenidos. Por otro lado, se ha comprobado la validez del modelo propuesto en el estudio de fenómenos ambientales dinámicos, en concreto la contaminación orgánica de aguas embalsadas. Finalmente, se ha demostrado un buen comportamiento del modelo en todos los casos ensayados, así como su flexibilidad, lo que le permite adaptarse a nuevos orígenes de datos, o nuevas metodologías de cálculo. Abstract This thesis aims to the study and analysis of techniques and models, in order to obtain biophysical parameters and environmental indicators in an automated way, using high temporal resolution satellite data. Firstly we have reviewed the main Earth Observation Programs, paying attention to those that provide high temporal resolution. Also have reviewed the methodologies and process flow diagrams in order to obtain quantitative parameters and qualitative documents, relating to various aspects of land cover, according to their adaptability to the peculiarities of the data. In the next stage, a model which allows obtaining environmental parameters, has been proposed. This structure integrates information from space sensors and ancillary data sources, using the methodologies presented in previous sections that permits the parameters calculation in an efficient and automated way. After this review of methodologies and the proposal of the model, we proceeded to carry out experiments, in order to check the behavior of the structure in real situations. From this, we derive the accuracy of the model. The sensors used in this work have been MODIS, which is a high temporal resolution sensor, and Thematic Mapper (TM), which is a medium spatial resolution instrument. This choice was motivated because they are reference sensors in environmental studies, as well as for the duration of their corresponding missions of data logging, and whose continuity seems assured. Among the experiments, we tested a methodology that allows the integration of data from cited sensors, we discussed a proposal for a temporal interpolation method for obtaining synthetic images with spatial resolution of TM (30 m) and temporal of MODIS (1 day), extending the application range of this one. Furthermore, we have analyzed some of the factors that affect the recorded data, such as the relative position of the satellite with the ground point, and the rainfall events, which alter the obtained results. On the other hand, we have proven the validity of the proposed model in the study of the organic contamination in inland water bodies. Finally, we have demonstrated a good performance of the proposed model in all cases tested, as well as its flexibility and adaptability.

Column Generation Algorithms for Nonlinear Optimization II: Numerical Investigations

García et al. present a class of column generation (CG) algorithms for nonlinear programs. Its main motivation from a theoretical viewpoint is that under some circumstances, finite convergence can be achieved, in much the same way as for the classic simplicial decomposition method; the main practical motivation is that within the class there are certain nonlinear column generation problems that can accelerate the convergence of a solution approach which generates a sequence of feasible points. This algorithm can, for example, accelerate simplicial decomposition schemes by making the subproblems nonlinear. This paper complements the theoretical study on the asymptotic and finite convergence of these methods given in [1] with an experimental study focused on their computational efficiency. Three types of numerical experiments are conducted. The first group of test problems has been designed to study the parameters involved in these methods. The second group has been designed to investigate the role and the computation of the prolongation of the generated columns to the relative boundary. The last one has been designed to carry out a more complete investigation of the difference in computational efficiency between linear and nonlinear column generation approaches. In order to carry out this investigation, we consider two types of test problems: the first one is the nonlinear, capacitated single-commodity network flow problem of which several large-scale instances with varied degrees of nonlinearity and total capacity are constructed and investigated, and the second one is a combined traffic assignment model

Do psicólogo no programa de residência multiprofissional em saúde: posição-sujeito, análise de discurso e psicanálise lacaniana

A residência multiprofissional em saúde é uma modalidade de ensino de pós graduação lato sensu, voltada para a educação em serviço. Emerge no contexto brasileiro como uma proposta complementar a fim de se atingir as metas e os princípios preconizados pelo sistema único de saúde (SUS), principalmente quanto à integralidade. Além de trazer implicações e lançar desafios ao exercício profissional do psicólogo, inserindo-o no entrelaçamento de campos densos e complexos (saúde, educação e políticas públicas), a modalidade propõe que profissionais com formações diferentes atuem num mesmo campo, com discussões e intervenções conjuntas. A questão que move a pesquisa é a posição-sujeito no programa de residência multiprofissional face ao modelo de educação-saúde vinculado. Assevera-se que a posição-sujeito é objeto discursivo deslizante (de tessitura simbólica) que toma em consideração o sujeito constituído no claudicar da linguagem e interpelado pelo inconsciente e que se manifesta como efeito de significantes em direção ao grande Outro. Para tal, vale-se da interface dos aportes teóricos da análise de discurso pêchetiana e da psicanálise lacaniana. A análise de discurso sustenta o discurso como efeito de sentidos mediados pela ideologia e ocupa-se, especialmente, da incursão da alteridade do discurso-outro sobre o mesmo. A psicanálise lacaniana, por sua vez, reitera a primazia do inconsciente estruturado como linguagem diante de um eu imaginário e versa para o sujeito marcado como falta que, dividido, faz do discurso o estatuto do significado. Assim, é proeminente na análise do objeto a metodologia indiciária dada ao caráter simbólico e cambiante da posição-sujeito no discurso. A análise se realizou mediante o dispositivo da interpretação como gesto analítico, que acompanha as elações próprias do objeto. O corpora é constituído por uma materialidade escrita e por uma oral. A escrita compõe-se de recortes de leis, portarias e resoluções que fundam a modalidade de residência multiprofissional e reforçam os ideias do sistema único de saúde; a materialidade oral compõe-se de recortes e fragmentos discursivos advindos da transcrição de supervisões realizadas mediante a prática clínica do psicólogo-residente na cena hospitalar. Da análise, conclui-se que a materialidade escrita se posta como campo-Outro que ordena a estrutura política da residência multiprofissional e direciona a manutenção da ordem e reprodução das relações hierárquicas mediante ideologia assujeitante. Essa materialidade, por sua vez, age como intradiscurso e reverbera-se na memória discursiva e na prática clínica. A posição-sujeito, no plano da articulação significante, faz deslizar e produzir sentidos que denotam ora a manutenção e reprodução de uma posição fusionada ao discurso médico, científico-positivista; ora a posição-sujeito é marcada pelo saber condicionado ao fetiche da mercadoria, deflagrando a ordem do capital nas insígnias da multiprofissionalidade e da educação permanente. O trabalho propiciou, enfim, acompanhar as transmutações da posição-sujeito, independentemente do indivíduo ou da naturalização de sentidos provenientes da função que exerce. O objeto posição-sujeito reiterou a construção da realidade a partir da condição faltante. É essa condição faltante e incompleta que outorga ao desejo o modo de o sujeito se posicionar desta e outra maneira - na formação, no trabalho, na vida.

Breast cancer teams:the impact of constitution, new cancer workload and methods of operation on their effectiveness

National guidance and clinical guidelines recommended multidisciplinary teams (MDTs) for cancer services in order to bring specialists in relevant disciplines together, ensure clinical decisions are fully informed, and to coordinate care effectively. However, the effectiveness of cancer teams was not previously evaluated systematically. A random sample of 72 breast cancer teams in England was studied (548 members in six core disciplines), stratified by region and caseload. Information about team constitution, processes, effectiveness, clinical performance, and members' mental well-being was gathered using appropriate instruments. Two input variables, team workload (P=0.009) and the proportion of breast care nurses (P=0.003), positively predicted overall clinical performance in multivariate analysis using a two-stage regression model. There were significant correlations between individual team inputs, team composition variables, and clinical performance. Some disciplines consistently perceived their team's effectiveness differently from the mean. Teams with shared leadership of their clinical decision-making were most effective. The mental well-being of team members appeared significantly better than in previous studies of cancer clinicians, the NHS, and the general population. This study established that team composition, working methods, and workloads are related to measures of effectiveness, including the quality of clinical care. © 2003 Cancer Research UK.

Contrast discrimination with simultaneous monocular and dichoptic masks

In experiments reported elsewhere at this conference, we have revealed two striking results concerning binocular interactions in a masking paradigm. First, at low mask contrasts, a dichoptic masking grating produces a small facilitatory effect on the detection of a similar test grating. Second, the psychometric slope for dichoptic masking starts high (Weibull ß~4) at detection threshold, becomes low (ß~1.2) in the facilitatory region, and then unusually steep at high mask contrasts (ß~5.5). Neither of these results is consistent with Legge's (1984 Vision Research 24 385 - 394) model of binocular summation, but they are predicted by a two-stage gain control model in which interocular suppression precedes binocular summation. Here, we pose a further challenge for this model by using a 'twin-mask' paradigm (cf Foley, 1994 Journal of the Optical Society of America A 11 1710 - 1719). In 2AFC experiments, observers detected a patch of grating (1 cycle deg-1, 200 ms) presented to one eye in the presence of a pedestal in the same eye and a spatially identical mask in the other eye. The pedestal and mask contrasts varied independently, producing a two-dimensional masking space in which the orthogonal axes (10X10 contrasts) represent conventional dichoptic and monocular masking. The resulting surface (100 thresholds) confirmed and extended the observations above, and fixed the six parameters in the model, which fitted the data well. With no adjustment of parameters, the model described performance in a further experiment where mask and test were presented to both eyes. Moreover, in both model and data, binocular summation was greater than a factor of v2 at detection threshold. We conclude that this two-stage nonlinear model, with interocular suppression, gives a good account of early binocular processes in the perception of contrast. [Supported by EPSRC Grant Reference: GR/S74515/01]

The innovation decision:an economic analysis

Studies of the determinants and effects of innovation commonly make an assumption about the way in which firms make the decision to innovate, but rarely test this assumption. Using a panel of Irish manufacturing firms we test the performance of two alternative models of the innovation decision, and find that a two-stage model (the firm decides whether to innovate, then whether to perform product only, process only or both) outperforms a one-stage, simultaneous model. We also find that external knowledge sourcing affects the innovation decision and the type of innovation undertaken in a way not previously recognised in the literature. © 2007 Elsevier Ltd. All rights reserved.

Numerical Comparison of the Drag Models of Granular Flows Applied to the Fast Pyrolysis of Biomass

The paper presents a comparison between the different drag models for granular flows developed in the literature and the effect of each one of them on the fast pyrolysis of wood. The process takes place on an 100 g/h lab scale bubbling fluidized bed reactor located at Aston University. FLUENT 6.3 is used as the modeling framework of the fluidized bed hydrodynamics, while the fast pyrolysis of the discrete wood particles is incorporated as an external user defined function (UDF) hooked to FLUENT’s main code structure. Three different drag models for granular flows are compared, namely the Gidaspow, Syamlal O’Brien, and Wen-Yu, already incorporated in FLUENT’s main code, and their impact on particle trajectory, heat transfer, degradation rate, product yields, and char residence time is quantified. The Eulerian approach is used to model the bubbling behavior of the sand, which is treated as a continuum. Biomass reaction kinetics is modeled according to the literature using a two-stage, semiglobal model that takes into account secondary reactions.

Mathematical modelling and control of agitated extraction columns

Liquid-liquid extraction has long been known as a unit operation that plays an important role in industry. This process is well known for its complexity and sensitivity to operation conditions. This thesis presents an attempt to explore the dynamics and control of this process using a systematic approach and state of the art control system design techniques. The process was studied first experimentally under carefully selected. operation conditions, which resembles the ranges employed practically under stable and efficient conditions. Data were collected at steady state conditions using adequate sampling techniques for the dispersed and continuous phases as well as during the transients of the column with the aid of a computer-based online data logging system and online concentration analysis. A stagewise single stage backflow model was improved to mimic the dynamic operation of the column. The developed model accounts for the variation in hydrodynamics, mass transfer, and physical properties throughout the length of the column. End effects were treated by addition of stages at the column entrances. Two parameters were incorporated in the model namely; mass transfer weight factor to correct for the assumption of no mass transfer in the. settling zones at each stage and the backmixing coefficients to handle the axial dispersion phenomena encountered in the course of column operation. The parameters were estimated by minimizing the differences between the experimental and the model predicted concentration profiles at steady state conditions using non-linear optimisation technique. The estimated values were then correlated as functions of operating parameters and were incorporated in·the model equations. The model equations comprise a stiff differential~algebraic system. This system was solved using the GEAR ODE solver. The calculated concentration profiles were compared to those experimentally measured. A very good agreement of the two profiles was achieved within a percent relative error of ±2.S%. The developed rigorous dynamic model of the extraction column was used to derive linear time-invariant reduced-order models that relate the input variables (agitator speed, solvent feed flowrate and concentration, feed concentration and flowrate) to the output variables (raffinate concentration and extract concentration) using the asymptotic method of system identification. The reduced-order models were shown to be accurate in capturing the dynamic behaviour of the process with a maximum modelling prediction error of I %. The simplicity and accuracy of the derived reduced-order models allow for control system design and analysis of such complicated processes. The extraction column is a typical multivariable process with agitator speed and solvent feed flowrate considered as manipulative variables; raffinate concentration and extract concentration as controlled variables and the feeds concentration and feed flowrate as disturbance variables. The control system design of the extraction process was tackled as multi-loop decentralised SISO (Single Input Single Output) as well as centralised MIMO (Multi-Input Multi-Output) system using both conventional and model-based control techniques such as IMC (Internal Model Control) and MPC (Model Predictive Control). Control performance of each control scheme was. studied in terms of stability, speed of response, sensitivity to modelling errors (robustness), setpoint tracking capabilities and load rejection. For decentralised control, multiple loops were assigned to pair.each manipulated variable with each controlled variable according to the interaction analysis and other pairing criteria such as relative gain array (RGA), singular value analysis (SVD). Loops namely Rotor speed-Raffinate concentration and Solvent flowrate Extract concentration showed weak interaction. Multivariable MPC has shown more effective performance compared to other conventional techniques since it accounts for loops interaction, time delays, and input-output variables constraints.

Modelling of wastewater treatment plants:how far shall we go with sophisticated modelling tools?

Several levels of complexity are available for modelling of wastewater treatment plants. Modelling local effects rely on computational fluid dynamics (CFD) approaches whereas activated sludge models (ASM) represent the global methodology. By applying both modelling approaches to pilot plant and full scale systems, this paper evaluates the value of each method and especially their potential combination. Model structure identification for ASM is discussed based on a full-scale closed loop oxidation ditch modelling. It is illustrated how and for what circumstances information obtained via CFD (computational fluid dynamics) analysis, residence time distribution (RTD) and other experimental means can be used. Furthermore, CFD analysis of the multiphase flow mechanisms is employed to obtain a correct description of the oxygenation capacity of the system studied, including an easy implementation of this information in the classical ASM modelling (e.g. oxygen transfer). The combination of CFD and activated sludge modelling of wastewater treatment processes is applied to three reactor configurations, a perfectly mixed reactor, a pilot scale activated sludge basin (ASB) and a real scale ASB. The application of the biological models to the CFD model is validated against experimentation for the pilot scale ASB and against a classical global ASM model response. A first step in the evaluation of the potential of the combined CFD-ASM model is performed using a full scale oxidation ditch system as testing scenario.

Lead isotope ratios of basalts from DSDP Leg 37 (Table 1)

Analyses of Pb from mid-ocean ridge basalts obtained from DSDP Leg 37 lie on a line of near-zero-age slope. The data seem consistent with an evolutionary model of three stages, the beginning of the second stage being at about 600 m.y. - the model age obtained for the least radiogenic Pb. The beginning of the third stage of evolution at the time of formation of the rocks apparently did not change the average Th/U ratio since measured values are consistent with the ratio deduced from Pb isotope ratios. Ratios of U/Pb are not consistent with Pb isotope ratios, however, thus ruling out a simple two-stage evolutionary model.

Online MBPeT dashboard : enabling performance testing as a service in the cloud

In this thesis, tool support is addressed for the combined disciplines of Model-based testing and performance testing. Model-based testing (MBT) utilizes abstract behavioral models to automate test generation, thus decreasing time and cost of test creation. MBT is a functional testing technique, thereby focusing on output, behavior, and functionality. Performance testing, however, is non-functional and is concerned with responsiveness and stability under various load conditions. MBPeT (Model-Based Performance evaluation Tool) is one such tool which utilizes probabilistic models, representing dynamic real-world user behavior patterns, to generate synthetic workload against a System Under Test and in turn carry out performance analysis based on key performance indicators (KPI). Developed at Åbo Akademi University, the MBPeT tool is currently comprised of a downloadable command-line based tool as well as a graphical user interface. The goal of this thesis project is two-fold: 1) to extend the existing MBPeT tool by deploying it as a web-based application, thereby removing the requirement of local installation, and 2) to design a user interface for this web application which will add new user interaction paradigms to the existing feature set of the tool. All phases of the MBPeT process will be realized via this single web deployment location including probabilistic model creation, test configurations, test session execution against a SUT with real-time monitoring of user configurable metric, and final test report generation and display. This web application (MBPeT Dashboard) is implemented with the Java programming language on top of the Vaadin framework for rich internet application development. The Vaadin framework handles the complicated web communications processes and front-end technologies, freeing developers to implement the business logic as well as the user interface in pure Java. A number of experiments are run in a case study environment to validate the functionality of the newly developed Dashboard application as well as the scalability of the solution implemented in handling multiple concurrent users. The results support a successful solution with regards to the functional and performance criteria defined, while improvements and optimizations are suggested to increase both of these factors.

Modeling the effect of asymmetric rolling on mechanical properties of Al-Mg alloys

The mechanical behavior under uniaxial tension of Al-Mg alloy 5182 pre-deformed in conventional rolling (CR), asymmetric rolling-continuous (ASRC), and asymmetric rolling-reversed (ASRR) was investigated and modeled with a rate dependent crystal plasticity finite element method and VPSC (Visco-Plastic Self Consistent) model. M-K theory combined with Yld2000 model by Barlat et al. (Int. J. Plasticity 2003, 19, 1297) was used to predict the strain-based and stress-based formability for AA 5182 material. It was concluded that the new ASRR process has very compatible formability with improved strength compared to CR process. These merits can be directly applied for clam-shell resistant design in rigid-packaging industry.

Examination of Inequalities in Hungary by Microsimulation in Consistency with Macro Data

Effective decision making uses various databases including both micro and macro level datasets. In many cases it is a big challenge to ensure the consistency of the two levels. Different types of problems can occur and several methods can be used to solve them. The paper concentrates on the input alignment of the households’ income for microsimulation, which means refers to improving the elements of a micro data survey (EU-SILC) by using macro data from administrative sources. We use a combined micro-macro model called ECONS-TAX for this improvement. We also produced model projections until 2015 which is important because the official EU-SILC micro database will only be available in Hungary in the summer of 2017. The paper presents our estimations about the dynamics of income elements and the changes in income inequalities. Results show that the aligned data provides a different level of income inequality, but does not affect the direction of change from year to year. However, when we analyzed policy change, the use of aligned data caused larger differences both in income levels and in their dynamics.

Prediction of PA12 melt viscosity in Laser Sintering by a Time and Temperature dependent rheological model

Ein auf Basis von Prozessdaten kalibriertes Viskositätsmodell wird vorgeschlagen und zur Vorhersage der Viskosität einer Polyamid 12 (PA12) Kunststoffschmelze als Funktion von Zeit, Temperatur und Schergeschwindigkeit angewandt. Im ersten Schritt wurde das Viskositätsmodell aus experimentellen Daten abgeleitet. Es beruht hauptsächlich auf dem drei-parametrigen Ansatz von Carreau, wobei zwei zusätzliche Verschiebungsfaktoren eingesetzt werden. Die Temperaturabhängigkeit der Viskosität wird mithilfe des Verschiebungsfaktors aT von Arrhenius berücksichtigt. Ein weiterer Verschiebungsfaktor aSC (Structural Change) wird eingeführt, der die Strukturänderung von PA12 als Folge der Prozessbedingungen beim Lasersintern beschreibt. Beobachtet wurde die Strukturänderung in Form einer signifikanten Viskositätserhöhung. Es wurde geschlussfolgert, dass diese Viskositätserhöhung auf einen Molmassenaufbau zurückzuführen ist und als Nachkondensation verstanden werden kann. Abhängig von den Zeit- und Temperaturbedingungen wurde festgestellt, dass die Viskosität als Folge des Molmassenaufbaus exponentiell gegen eine irreversible Grenze strebt. Die Geschwindigkeit dieser Nachkondensation ist zeit- und temperaturabhängig. Es wird angenommen, dass die Pulverbetttemperatur einen Molmassenaufbau verursacht und es damit zur Kettenverlängerung kommt. Dieser fortschreitende Prozess der zunehmenden Kettenlängen setzt molekulare Beweglichkeit herab und unterbindet die weitere Nachkondensation. Der Verschiebungsfaktor aSC drückt diese physikalisch-chemische Modellvorstellung aus und beinhaltet zwei zusätzliche Parameter. Der Parameter aSC,UL entspricht der oberen Viskositätsgrenze, wohingegen k0 die Strukturänderungsrate angibt. Es wurde weiterhin festgestellt, dass es folglich nützlich ist zwischen einer Fließaktivierungsenergie und einer Strukturänderungsaktivierungsenergie für die Berechnung von aT und aSC zu unterscheiden. Die Optimierung der Modellparameter erfolgte mithilfe eines genetischen Algorithmus. Zwischen berechneten und gemessenen Viskositäten wurde eine gute Übereinstimmung gefunden, so dass das Viskositätsmodell in der Lage ist die Viskosität einer PA12 Kunststoffschmelze als Folge eines kombinierten Lasersinter Zeit- und Temperatureinflusses vorherzusagen. Das Modell wurde im zweiten Schritt angewandt, um die Viskosität während des Lasersinter-Prozesses in Abhängigkeit von der Energiedichte zu berechnen. Hierzu wurden Prozessdaten, wie Schmelzetemperatur und Belichtungszeit benutzt, die mithilfe einer High-Speed Thermografiekamera on-line gemessen wurden. Abschließend wurde der Einfluss der Strukturänderung auf das Viskositätsniveau im Prozess aufgezeigt.

Modelling of two-stage anaerobic digestion using the IWA Anaerobic Digestion Model No. 1 (ADM1)

The aim of the study presented was to implement a process model to simulate the dynamic behaviour of a pilot-scale process for anaerobic two-stage digestion of sewage sludge. The model implemented was initiated to support experimental investigations of the anaerobic two-stage digestion process. The model concept implemented in the simulation software package MATLAB(TM)/Simulink(R) is a derivative of the IWA Anaerobic Digestion Model No.1 (ADM1) that has been developed by the IWA task group for mathematical modelling of anaerobic processes. In the present study the original model concept has been adapted and applied to replicate a two-stage digestion process. Testing procedures, including balance checks and 'benchmarking' tests were carried out to verify the accuracy of the implementation. These combined measures ensured a faultless model implementation without numerical inconsistencies. Parameters for both, the thermophilic and the mesophilic process stage, have been estimated successfully using data from lab-scale experiments described in literature. Due to the high number of parameters in the structured model, it was necessary to develop a customised procedure that limited the range of parameters to be estimated. The accuracy of the optimised parameter sets has been assessed against experimental data from pilot-scale experiments. Under these conditions, the model predicted reasonably well the dynamic behaviour of a two-stage digestion process in pilot scale. (C) 2004 Elsevier Ltd. All rights reserved.