Critical evaluation of diameter increment modelling in the Great Lakes region

Simulations of forest stand dynamics in a modelling framework including Forest Vegetation Simulator (FVS) are diameter driven, thus the diameter or basal area increment model needs a special attention. This dissertation critically evaluates diameter or basal area increment models and modelling approaches in the context of the Great Lakes region of the United States and Canada. A set of related studies are presented that critically evaluate the sub-model for change in individual tree basal diameter used in the Forest Vegetation Simulator (FVS), a dominant forestry model in the Great Lakes region. Various historical implementations of the STEMS (Stand and Tree Evaluation and Modeling System) family of diameter increment models, including the current public release of the Lake States variant of FVS (LS-FVS), were tested for the 30 most common tree species using data from the Michigan Forest Inventory and Analysis (FIA) program. The results showed that current public release of the LS-FVS diameter increment model over-predicts 10-year diameter increment by 17% on average. Also the study affirms that a simple adjustment factor as a function of a single predictor, dbh (diameter at breast height) used in the past versions, provides an inadequate correction of model prediction bias. In order to re-engineer the basal diameter increment model, the historical, conceptual and philosophical differences among the individual tree increment model families and their modelling approaches were analyzed and discussed. Two underlying conceptual approaches toward diameter or basal area increment modelling have been often used: the potential-modifier (POTMOD) and composite (COMP) approaches, which are exemplified by the STEMS/TWIGS and Prognosis models, respectively. It is argued that both approaches essentially use a similar base function and neither is conceptually different from a biological perspective, even though they look different in their model forms. No matter what modelling approach is used, the base function is the foundation of an increment model. Two base functions ��� gamma and Box-Lucas ��� were identified as candidate base functions for forestry applications. The results of a comparative analysis of empirical fits showed that quality of fit is essentially similar, and both are sufficiently detailed and flexible for forestry applications. The choice of either base function in order to model diameter or basal area increment is dependent upon personal preference; however, the gamma base function may be preferred over the Box-Lucas, as it fits the periodic increment data in both a linear and nonlinear composite model form. Finally, the utility of site index as a predictor variable has been criticized, as it has been widely used in models for complex, mixed species forest stands though not well suited for this purpose. An alternative to site index in an increment model was explored, using site index and a combination of climate variables and Forest Ecosystem Classification (FEC) ecosites and data from the Province of Ontario, Canada. The results showed that a combination of climate and FEC ecosites variables can replace site index in the diameter increment model.

Present state of global wetland extent and wetland methane modelling: methodology of a model inter-comparison project (WETCHIMP)

The Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP) was created to evaluate our present ability to simulate large-scale wetland characteristics and corresponding methane (CH4) emissions. A multi-model comparison is essential to evaluate the key uncertainties in the mechanisms and parameters leading to methane emissions. Ten modelling groups joined WETCHIMP to run eight global and two regional models with a common experimental protocol using the same climate and atmospheric carbon dioxide (CO2) forcing datasets. We reported the main conclusions from the intercomparison effort in a companion paper (Melton et al., 2013). Here we provide technical details for the six experiments, which included an equilibrium, a transient, and an optimized run plus three sensitivity experiments (temperature, precipitation, and atmospheric CO2 concentration). The diversity of approaches used by the models is summarized through a series of conceptual figures, and is used to evaluate the wide range of wetland extent and CH4 fluxes predicted by the models in the equilibrium run. We discuss relationships among the various approaches and patterns in consistencies of these model predictions. Within this group of models, there are three broad classes of methods used to estimate wetland extent: prescribed based on wetland distribution maps, prognostic relationships between hydrological states based on satellite observations, and explicit hydrological mass balances. A larger variety of approaches was used to estimate the net CH4 fluxes from wetland systems. Even though modelling of wetland extent and CH4 emissions has progressed significantly over recent decades, large uncertainties still exist when estimating CH4 emissions: there is little consensus on model structure or complexity due to knowledge gaps, different aims of the models, and the range of temporal and spatial resolutions of the models.

Prospective memory, executive functions, and metacognition are already differentiated in young elementary school children: Evidence from latent factor modelling

This study investigated the empirical differentiation of prospective memory, executive functions, and metacognition and their structural relationships in 119 elementary school children (M = 95 months, SD = 4.8 months). These cognitive abilities share many characteristics on the theoretical level and are all highly relevant in many everyday contexts when intentions must be executed. Nevertheless, their empirical relationships have not been examined on the latent level, although an empirical approach would contribute to our knowledge concerning the differentiation of cognitive abilities during childhood. We administered a computerized event-based prospective memory task, three executive function tasks (updating, inhibition, shifting), and a metacognitive control task in the context of spelling. Confirmatory factor analysis revealed that the three cognitive abilities are already empirically differentiable in young elementary school children. At the same time, prospective memory and executive functions were found to be strongly related, and there was also a close link between prospective memory and metacognitive control. Furthermore, executive functions and metacognitive control were marginally significantly related. The findings are discussed within a framework of developmental differentiation and conceptual similarities and differences.

Temporal variability of damage potential on roads as a conceptual contribution towards a short-term avalanche risk simulation

The fatality risk caused by avalanches on road networks can be analysed using a long-term approach, resulting in a mean value of risk, and with emphasis on short-term fluctuations due to the temporal variability of both, the hazard potential and the damage potential. In this study, the approach for analysing the long-term fatality risk has been adapted by modelling the highly variable short-term risk. The emphasis was on the temporal variability of the damage potential and the related risk peaks. For defined hazard scenarios resulting from classified amounts of snow accumulation, the fatality risk was calculated by modelling the hazard potential and observing the traffic volume. The avalanche occurrence probability was calculated using a statistical relationship between new snow height and observed avalanche releases. The number of persons at risk was determined from the recorded traffic density. The method resulted in a value for the fatality risk within the observed time frame for the studied road segment. The long-term fatality risk due to snow avalanches as well as the short-term fatality risk was compared to the average fatality risk due to traffic accidents. The application of the method had shown that the long-term avalanche risk is lower than the fatality risk due to traffic accidents. The analyses of short-term avalanche-induced fatality risk provided risk peaks that were 50 times higher than the statistical accident risk. Apart from situations with high hazard level and high traffic density, risk peaks result from both, a high hazard level combined with a low traffic density and a high traffic density combined with a low hazard level. This provided evidence for the importance of the temporal variability of the damage potential for risk simulations on road networks. The assumed dependence of the risk calculation on the sum of precipitation within three days is a simplified model. Thus, further research is needed for an improved determination of the diurnal avalanche probability. Nevertheless, the presented approach may contribute as a conceptual step towards a risk-based decision-making in risk management.

The morphofunctional approach to emotion modelling in robotics

In this conceptual paper, we discuss two areas of research in robotics, robotic models of emotion and morphofunctional machines, and we explore the scope for potential cross-fertilization between them. We shift the focus in robot models of emotion from information-theoretic aspects of appraisal to the interactive significance of bodily dispositions. Typical emotional phenomena such as arousal and action readiness can be interpreted as morphofunctional processes, and their functionality may be replicated in robotic systems with morphologies that can be modulated for real-time adaptation. We investigate the control requirements for such systems, and present a possible bio-inspired architecture, based on the division of control between neural and endocrine systems in humans and animals. We suggest that emotional epi- sodes can be understood as emergent from the coordination of action control and action-readiness, respectively. This stress on morphology complements existing research on the information-theoretic aspects of emotion.

Agent Architecture Modelling at the Knowledge Level

The definition of an agent architecture at the knowledge level makes emphasis on the knowledge role played by the data interchanged between the agent components and makes explicit this data interchange this makes easier the reuse of these knowledge structures independently of the implementation This article defines a generic task model of an agent architecture and refines some of these tasks using the interference diagrams. Finally, a operationalisation of this conceptual model using the rule-oriented language Jess is shown. knowledge level,

Modelling diffusion of photovoltaic: concepts and applications

Innovation studies have been interest of not only the scholars from various fields such as economics, management and sociology but also industrial practitioners and policy makers. In this vast and fruitful field, the theory of diffusion of innovations, which has been driven by a sociological approach, has played a vital role in our understanding of the mechanisms behind industrial change. In this paper, our aim is to give a state of art review of diffusion of innovation models in a structural and conceptual way with special reference to photovoltaic. We argue firstly, as an underlying background, how diffusion of innovations theory differs from other innovation studies. Secondly we give a brief taxonomical review of modelling methodologies together with comparative discussions. And finally we put the wealth of modelling in the context of photovoltaic diffusion and suggest some future directions.

Development and implementation of an air quality integrated assessment modelling system for the Iberian Peninsula

La mejora de la calidad del aire es una tarea eminentemente interdisciplinaria. Dada la gran variedad de ciencias y partes involucradas, dicha mejora requiere de herramientas de evaluaci��n simples y completamente integradas. La modelizaci��n para la evaluaci��n integrada (integrated assessment modeling) ha demostrado ser una soluci��n adecuada para la descripci��n de los sistemas de contaminaci��n atmosf��rica puesto que considera cada una de las etapas involucradas: emisiones, qu��mica y dispersi��n atmosf��rica, impactos ambientales asociados y potencial de disminuci��n. Varios modelos de evaluaci��n integrada ya est��n disponibles a escala continental, cubriendo cada una de las etapas antesmencionadas, siendo el modelo GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) el m��s reconocido y usado en el contexto europeo de toma de decisiones medioambientales. Sin embargo, el manejo de la calidad del aire a escala nacional/regional dentro del marco de la evaluaci��n integrada es deseable. Esto sin embargo, no se lleva a cabo de manera satisfactoria con modelos a escala europea debido a la falta de resoluci��n espacial o de detalle en los datos auxiliares, principalmente los inventarios de emisi��n y los patrones meteorol��gicos, entre otros. El objetivo de esta tesis es presentar los desarrollos en el dise��o y aplicaci��n de un modelo de evaluaci��n integrada especialmente concebido para Espa��a y Portugal. El modelo AERIS (Atmospheric Evaluation and Research Integrated system for Spain) es capaz de cuantificar perfiles de concentraci��n para varios contaminantes (NO2, SO2, PM10, PM2,5, NH3 y O3), el dep��sito atmosf��rico de especies de azufre y nitr��geno as�� como sus impactos en cultivos, vegetaci��n, ecosistemas y salud como respuesta a cambios porcentuales en las emisiones de sectores relevantes. La versi��n actual de AERIS considera 20 sectores de emisi��n, ya sea equivalentes a sectores individuales SNAP o macrosectores, cuya contribuci��n a los niveles de calidad del aire, dep��sito e impactos han sido modelados a trav��s de matrices fuentereceptor (SRMs). Estas matrices son constantes de proporcionalidad que relacionan cambios en emisiones con diferentes indicadores de calidad del aire y han sido obtenidas a trav��s de parametrizaciones estad��sticas de un modelo de calidad del aire (AQM). Para el caso concreto de AERIS, su modelo de calidad del aire ���de origen��� consisti�� en el modelo WRF para la meteorolog��a y en el modelo CMAQ para los procesos qu��mico-atmosf��ricos. La cuantificaci��n del dep��sito atmosf��rico, de los impactos en ecosistemas, cultivos, vegetaci��n y salud humana se ha realizado siguiendo las metodolog��as est��ndar establecidas bajo los marcos internacionales de negociaci��n, tales como CLRTAP. La estructura de programaci��n est�� basada en MATLAB��, permitiendo gran compatibilidad con software t��pico de escritorio comoMicrosoft Excel�� o ArcGIS��. En relaci��n con los niveles de calidad del aire, AERIS es capaz de proveer datos de media anual y media mensual, as�� como el 19o valor horario m��s alto paraNO2, el 25o valor horario y el 4o valor diario m��s altos para SO2, el 36o valor diario m��s alto para PM10, el 26o valor octohorario m��s alto, SOMO35 y AOT40 para O3. En relaci��n al dep��sito atmosf��rico, el dep��sito acumulado anual por unidad de area de especies de nitr��geno oxidado y reducido al igual que de azufre pueden ser determinados. Cuando los valores anteriormente mencionados se relacionan con caracter��sticas del dominio modelado tales como uso de suelo, cubiertas vegetales y forestales, censos poblacionales o estudios epidemiol��gicos, un gran n��mero de impactos puede ser calculado. Centr��ndose en los impactos a ecosistemas y suelos, AERIS es capaz de estimar las superaciones de cargas cr��ticas y las superaciones medias acumuladas para especies de nitr��geno y azufre. Los da��os a bosques se calculan como una superaci��n de los niveles cr��ticos de NO2 y SO2 establecidos. Adem��s, AERIS es capaz de cuantificar da��os causados por O3 y SO2 en vid, ma��z, patata, arroz, girasol, tabaco, tomate, sand��a y trigo. Los impactos en salud humana han sido modelados como consecuencia de la exposici��n a PM2,5 y O3 y cuantificados como p��rdidas en la esperanza de vida estad��stica e indicadores de mortalidad prematura. La exactitud del modelo de evaluaci��n integrada ha sido contrastada estad��sticamente con los resultados obtenidos por el modelo de calidad del aire convencional, exhibiendo en la mayor��a de los casos un buen nivel de correspondencia. Debido a que la cuantificaci��n de los impactos no es llevada a cabo directamente por el modelo de calidad del aire, un an��lisis de credibilidad ha sido realizado mediante la comparaci��n de los resultados de AERIS con los de GAINS para un escenario de emisiones determinado. El an��lisis revel�� un buen nivel de correspondencia en las medias y en las distribuciones probabil��sticas de los conjuntos de datos. Las pruebas de verificaci��n que fueron aplicadas a AERIS sugieren que los resultados son suficientemente consistentes para ser considerados como razonables y realistas. En conclusi��n, la principal motivaci��n para la creaci��n del modelo fue el producir una herramienta confiable y a la vez simple para el soporte de las partes involucradas en la toma de decisiones, de cara a analizar diferentes escenarios ���y si��� con un bajo coste computacional. La interacci��n con pol��ticos y otros actores dict�� encontrar un compromiso entre la complejidad del modeladomedioambiental con el car��cter conciso de las pol��ticas, siendo esto algo que AERIS refleja en sus estructuras conceptual y computacional. Finalmente, cabe decir que AERIS ha sido creado para su uso exclusivo dentro de un marco de evaluaci��n y de ninguna manera debe ser considerado como un sustituto de los modelos de calidad del aire ordinarios. ABSTRACT Improving air quality is an eminently inter-disciplinary task. The wide variety of sciences and stakeholders that are involved call for having simple yet fully-integrated and reliable evaluation tools available. Integrated AssessmentModeling has proved to be a suitable solution for the description of air pollution systems due to the fact that it considers each of the involved stages: emissions, atmospheric chemistry, dispersion, environmental impacts and abatement potentials. Some integrated assessment models are available at European scale that cover each of the before mentioned stages, being the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model the most recognized and widely-used within a European policy-making context. However, addressing air quality at the national/regional scale under an integrated assessment framework is desirable. To do so, European-scale models do not provide enough spatial resolution or detail in their ancillary data sources, mainly emission inventories and local meteorology patterns as well as associated results. The objective of this dissertation is to present the developments in the design and application of an Integrated Assessment Model especially conceived for Spain and Portugal. The Atmospheric Evaluation and Research Integrated system for Spain (AERIS) is able to quantify concentration profiles for several pollutants (NO2, SO2, PM10, PM2.5, NH3 and O3), the atmospheric deposition of sulfur and nitrogen species and their related impacts on crops, vegetation, ecosystems and health as a response to percentual changes in the emissions of relevant sectors. The current version of AERIS considers 20 emission sectors, either corresponding to individual SNAP sectors or macrosectors, whose contribution to air quality levels, deposition and impacts have been modeled through the use of source-receptor matrices (SRMs). Thesematrices are proportionality constants that relate emission changes with different air quality indicators and have been derived through statistical parameterizations of an air qualitymodeling system (AQM). For the concrete case of AERIS, its parent AQM relied on the WRF model for meteorology and on the CMAQ model for atmospheric chemical processes. The quantification of atmospheric deposition, impacts on ecosystems, crops, vegetation and human health has been carried out following the standard methodologies established under international negotiation frameworks such as CLRTAP. The programming structure isMATLAB �� -based, allowing great compatibility with typical software such as Microsoft Excel �� or ArcGIS �� Regarding air quality levels, AERIS is able to provide mean annual andmean monthly concentration values, as well as the indicators established in Directive 2008/50/EC, namely the 19th highest hourly value for NO2, the 25th highest daily value and the 4th highest hourly value for SO2, the 36th highest daily value of PM10, the 26th highest maximum 8-hour daily value, SOMO35 and AOT40 for O3. Regarding atmospheric deposition, the annual accumulated deposition per unit of area of species of oxidized and reduced nitrogen as well as sulfur can be estimated. When relating the before mentioned values with specific characteristics of the modeling domain such as land use, forest and crops covers, population counts and epidemiological studies, a wide array of impacts can be calculated. When focusing on impacts on ecosystems and soils, AERIS is able to estimate critical load exceedances and accumulated average exceedances for nitrogen and sulfur species. Damage on forests is estimated as an exceedance of established critical levels of NO2 and SO2. Additionally, AERIS is able to quantify damage caused by O3 and SO2 on grapes, maize, potato, rice, sunflower, tobacco, tomato, watermelon and wheat. Impacts on human health aremodeled as a consequence of exposure to PM2.5 and O3 and quantified as losses in statistical life expectancy and premature mortality indicators. The accuracy of the IAM has been tested by statistically contrasting the obtained results with those yielded by the conventional AQM, exhibiting in most cases a good agreement level. Due to the fact that impacts cannot be directly produced by the AQM, a credibility analysis was carried out for the outputs of AERIS for a given emission scenario by comparing them through probability tests against the performance of GAINS for the same scenario. This analysis revealed a good correspondence in the mean behavior and the probabilistic distributions of the datasets. The verification tests that were applied to AERIS suggest that results are consistent enough to be credited as reasonable and realistic. In conclusion, the main reason thatmotivated the creation of this model was to produce a reliable yet simple screening tool that would provide decision and policy making support for different ���what-if��� scenarios at a low computing cost. The interaction with politicians and other stakeholders dictated that reconciling the complexity of modeling with the conciseness of policies should be reflected by AERIS in both, its conceptual and computational structures. It should be noted however, that AERIS has been created under a policy-driven framework and by no means should be considered as a substitute of the ordinary AQM.

Definici��n e implantaci��n de herramientas avanzadas 3D en el dise��o integrado y eficiente de sistemas HVAC en buques, desde el proyecto conceptual hasta la producci��n

Uno de los aspectos m��s complicados del dise��o de sistemas HVAC en buques es la correcta evaluaci��n de las necesidades de aire fresco y el correcto dimensionado de los conductos que suministran dicho aire y evacuan el calor generado a bordo. Contrariamente a lo que sucede en los sistemas de tuber��as, las caracter��sticas particulares del caudal de aire hacen que el dimensionado de los conductos sea muy sensible al trazado y geometr��a de los mismos, por lo que para obtener un buen dise��o es necesaria una relaci��n muy estrecha y una integraci��n bidireccional entre los c��lculos y el trazado de los propios conductos en el buque. Asumida la utilizaci��n de sistemas CAD/CAM para las tareas de dise��o, hist��ricamente, aquellos que permit��an modelar conductos HVAC no inclu��an en su alcance de suministro los aspectos de c��lculo, y como consecuencia de ello, el trazado de conductos se reduc��a a la inclusi��n en el modelo 3D de circuitos y sistemas previamente calculados y dimensionados, As��, serv��an ��nicamente para calcular interferencias con otros elementos del modelo 3D y para obtener posteriormente planos de fabricaci��n y montaje. Esto, que por s�� no es poco, dejaba el dise��o de sistemas HVAC pendiente de una importante interacci��n manual y de habituales retrabajos, ya que cualquier modificaci��n en el trazado de los conductos, consecuencia de otras necesidades del dise��o, obligaba a los dise��adores a recalcular y redimensionar los conductos en un entorno diferente al del propio sistema CAD/CAM, y volver a realizar el modelado de los mismos, reduciendo significativamente las ventajas de la utilizaci��n de un modelo 3D. Partiendo de esta situaci��n real, y con objeto de solucionar el problema que para el dise��o y la propia producci��n del buque se creaba, se concibi�� una herramienta que permitiera la definici��n en el modelo 3D de diagramas de ventilaci��n, el c��lculo de p��rdidas de presi��n, el dimensionado autom��tico de los conductos, y que toda esta informaci��n pudiera estar disponible y reutilizarse en las etapas posteriores del dise��o. Con ello, los dise��adores podr��an realizar su trabajo en un entorno ��nico, totalmente integrado con el resto de disciplinas. El objeto de esta Tesis Doctoral es analizar en detalle el problema y las ineficiencias actuales del dise��o de HVAC, describir la innovadora herramienta concebida para paliar estas ineficiencias, detallando las bases sobre la que se construye, y destacar las ventajas que se obtienen de su uso. La herramienta en cuesti��n fue concebida como una funcionalidad adicional del sistema CAD/CAM naval FORAN, referente tecnol��gico en el mundo del dise��o y la construcci��n navales, y como consecuencia de ellos se llev�� a cabo el desarrollo correspondiente. En la actualidad, el sistema FORAN incluye en su alcance de suministro una primera versi��n de esta herramienta, cuya utilidad queda avalada por el uso que de la misma hacen astilleros y oficinas t��cnicas en todo el mundo. Esta Tesis Doctoral es eminentemente pr��ctica. No es un estudio te��rico de dudosa aplicaci��n, sino que tiene por objeto aportar una soluci��n eficiente a un problema real que muchos astilleros y oficinas t��cnicas, incluidas los m��s avanzados, padecen hoy en d��a. No tiene otra motivaci��n que servir de ayuda para lograr dise��ar y construir mejores barcos, en un plazo m��s corto, y a un coste menor. Nada m��s, pero nada menos. ABSTRACT One of the most complicated aspects of the design of HVAC systems in shipbuilding is the correct evaluation of the fresh air needs, the correct balancing of the ducts that supply this air and evacuate the existing heat on board. In opposition to piping systems, due to the particular characteristics of the air flow, the balancing of the ducts is very sensitive to the routing and the aspect of the ducts, so the correct design requires a close interconnectivity between calculations and routing. Already assumed the use of CAD/CAM systems for design tasks, historically, those CAD/CAM systems capable of modelling HVAC ducts did not cover calculation aspects, with the result that the routing of HVAC ducts was reduced solely to the input of previously balanced circuits into the 3D Product Model for the purpose of interference checking and generation of fabrication and assembly drawings. This situation, not negligible at all, put the design of HVAC ducts very dependent on manual operations and common rework task, as any modification in the routing of the HVAC ducts, derived from design needs, obliged engineers to re-balance the ducts and eventually to re-size them independently of the CAD-CAM environment, thus annulling the advantages of the 3D Product Model. With this situation in mind, and with the objective of filling the gap created in the design and construction of the ship, it was conceived a tool allowing the definition, within the 3D Product model, of HVAC diagrams, the calculation of pressure drops, the automatic dimensioning of ducts. With this, engineers could make the complete HVAC design in a single working environment, fully integrated with the rest of the disciplines. The present Ph. D. thesis analyses in deep the existing problem and the current lack of efficiency in HVAC design, describes the innovative tool conceived to minimize it, details the basis on which the tool is built, and highlights the advantages of its use. This tool was conceived as an additional functionality of the marine CAD/CAM system FORAN, a technological reference in the shipdesign and shipbuilding industry. As a consequence, it was developed, and nowadays FORAN System includes in its scope of supply a first version of the tool, with its usefulness endorsed by the fact that it is used by shipyards and shipdesign offices all over the world. This Ph. D. thesis is on top everything, of practical nature. It is not a theoretical study with doubtful application. On the contrary, its objective is to provide with an efficient solution for solving a real problem that many shipyards and shipdesign offices, including those more advanced, suffer nowadays. It has no other motivation that to help in the process of designing and building better and cheaper ships, within a shorter deliver time. Nothing more, but nothing less.

A formal framework for modelling complex network management systems

Society today is completely dependent on computer networks, the Internet and distributed systems, which place at our disposal the necessary services to perform our daily tasks. Subconsciously, we rely increasingly on network management systems. These systems allow us to, in general, maintain, manage, configure, scale, adapt, modify, edit, protect, and enhance the main distributed systems. Their role is secondary and is unknown and transparent to the users. They provide the necessary support to maintain the distributed systems whose services we use every day. If we do not consider network management systems during the development stage of distributed systems, then there could be serious consequences or even total failures in the development of the distributed system. It is necessary, therefore, to consider the management of the systems within the design of the distributed systems and to systematise their design to minimise the impact of network management in distributed systems projects. In this paper, we present a framework that allows the design of network management systems systematically. To accomplish this goal, formal modelling tools are used for modelling different views sequentially proposed of the same problem. These views cover all the aspects that are involved in the system; based on process definitions for identifying responsible and defining the involved agents to propose the deployment in a distributed architecture that is both feasible and appropriate.

Modelling a biomass supply chain through discrete-event simulation

The organizational structure of the companies in the biomass energy sector, regarding the supply chain management services, can be greatly improved through the use of software decision support tools. These tools should be able to provide real-time alternative scenarios when deviations from the initial production plans are observed. To make this possible it is necessary to have representative production chain process models where several scenarios and solutions can be evaluated accurately. Due to its nature, this type of process is more adequately represented by means of event-based models. In particular, this work presents the modelling of a typical biomass production chain using the computing platform SIMEVENTS. Throughout the article details about the conceptual model, as well as simulation results, are provided

A work domain analysis framework for modelling intensive care unit patients

Work domain analysis (WDA) has been applied to a range of complex work domains, but few WDAs have been undertaken in medical contexts. One pioneering effort suggested that clinical abstraction is not based on means-ends relations, whereas another effort downplayed the role of bio-regulatory mechanisms. In this paper it is argued that bio-regulatory mechanisms that govern physiological behaviour must be part of WDA models of patients as the systems at the core of intensive care units. Furthermore it is argued that because the inner functioning of patients is not completely known, clinical abstraction is based on hypothetico-deductive abstract reasoning. This paper presents an alternative modelling framework that conforms to the broader aspirations of WDA. A modified version of the viable systems model is used to represent the patient system as a nested dissipative structure while aspects of the recognition primed decision model are used to represent the information resources available to clinicians in ways that support lsquoif...thenrsquo conceptual relations. These two frameworks come together to form the recursive diagnostic framework, which may provide a more appropriate foundation for information display design in the intensive care unit.

Modelling the conversion of Colombian lowland ecosystems since 1940: Drivers, patterns and rates

In biologically mega-diverse countries that are undergoing rapid human landscape transformation, it is important to understand and model the patterns of land cover change. This problem is particularly acute in Colombia, where lowland forests are being rapidly cleared for cropping and ranching. We apply a conceptual model with a nested set of a priori predictions to analyse the spatial and temporal patterns of land cover change for six 50-100 km(2) case study areas in lowland ecosystems of Colombia. Our analysis included soil fertility, a cost-distance function, and neighbourhood of forest and secondary vegetation cover as independent variables. Deforestation and forest regrowth are tested using logistic regression analysis and an information criterion approach to rank the models and predictor variables. The results show that: (a) overall the process of deforestation is better predicted by the full model containing all variables, while for regrowth the model containing only the auto-correlated neighbourhood terms is a better predictor; (b) overall consistent patterns emerge, although there are variations across regions and time; and (c) during the transformation process, both the order of importance and significance of the drivers change. Forest cover follows a consistent logistic decline pattern across regions, with introduced pastures being the major replacement land cover type. Forest stabilizes at 2-10% of the original cover, with an average patch size of 15.4 (+/- 9.2) ha. We discuss the implications of the observed patterns and rates of land cover change for conservation planning in countries with high rates of deforestation. (c) 2005 Elsevier Ltd. All rights reserved.

The mathematical modelling of the environmental performance of buildings as an aid in the design process

This thesis is a theoretical study of the accuracy and usability of models that attempt to represent the environmental control system of buildings in order to improve environmental design. These models have evolved from crude representations of a building and its environment through to an accurate representation of the dynamic characteristics of the environmental stimuli on buildings. Each generation of models has had its own particular influence on built form. This thesis analyses the theory, structure and data of such models in terms of their accuracy of simulation and therefore their validity in influencing built form. The models are also analysed in terms of their compatability with the design process and hence their ability to aid designers. The conclusions are that such models are unlikely to improve environmental performance since: a the models can only be applied to a limited number of building types, b they can only be applied to a restricted number of the characteristics of a design, c they can only be employed after many major environmental decisions have been made, d the data used in models is inadequate and unrepresentative, e models do not account for occupant interaction in environmental control. It is argued that further improvements in the accuracy of simulation of environmental control will not significantly improve environmental design. This is based on the premise that strategic environmental decisions are made at the conceptual stages of design whereas models influence the detailed stages of design. It is hypothesised that if models are to improve environmental design it must be through the analysis of building typologies which provides a method of feedback between models and the conceptual stages of design. Field studies are presented to describe a method by which typologies can be analysed and a theoretical framework is described which provides a basis for further research into the implications of the morphology of buildings on environmental design.

CFD-modelling of insulation debris transport phenomena in water flow

The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behavior of emergency core cooling systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems. Open questions of generic interest are the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow and the particle load on strainers and corresponding pressure drop. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/G��rlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/G��rlitz, the theoretical modeling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. Whereas the paper Alt et al. is focused on the experiments in the present paper the basic concepts for CFD modeling are described and feasibility studies including the conceptual design of the experiments are presented.