Efficient numerical methods for global linear instability. Analysis and modeling of non-orthogonal swept attachment-line boundary layer flow

The aim of this thesis is to study the mechanisms of instability that occur in swept wings when the angle of attack increases. For this, a simplified model for the a simplified model for the non-orthogonal swept leading edge boundary layer has been used as well as different numerical techniques in order to solve the linear stability problem that describes the behavior of perturbations superposed upon this base flow. Two different approaches, matrix-free and matrix forming methods, have been validated using direct numerical simulations with spectral resolution. In this way, flow instability in the non-orthogonal swept attachment-line boundary layer is addressed in a linear analysis framework via the solution of the pertinent global (Bi-Global) PDE-based eigenvalue problem. Subsequently, a simple extension of the extended G¨ortler-H¨ammerlin ODEbased polynomial model proposed by Theofilis, Fedorov, Obrist & Dallmann (2003) for orthogonal flow, which includes previous models as particular cases and recovers global instability analysis results, is presented for non-orthogonal flow. Direct numerical simulations have been used to verify the stability results and unravel the limits of validity of the basic flow model analyzed. The effect of the angle of attack, AoA, on the critical conditions of the non-orthogonal problem has been documented; an increase of the angle of attack, from AoA = 0 (orthogonal flow) up to values close to _/2 which make the assumptions under which the basic flow is derived questionable, is found to systematically destabilize the flow. The critical conditions of non-orthogonal flows at 0 _ AoA _ _/2 are shown to be recoverable from those of orthogonal flow, via a simple analytical transformation involving AoA. These results can help to understand the mechanisms of destabilization that occurs in the attachment line of wings at finite angles of attack. Studies taking into account variations of the pressure field in the basic flow or the extension to compressible flows are issues that remain open. El objetivo de esta tesis es estudiar los mecanismos de la inestabilidad que se producen en ciertos dispositivos aerodinámicos cuando se aumenta el ángulo de ataque. Para ello se ha utilizado un modelo simplificado del flujo de base, así como diferentes técnicas numéricas, con el fin de resolver el problema de estabilidad lineal asociado que describe el comportamiento de las perturbaciones. Estos métodos; sin y con formación de matriz, se han validado utilizando simulaciones numéricas directas con resolución espectral. De esta manera, la inestabilidad del flujo de capa límite laminar oblicuo entorno a la línea de estancamiento se aborda en un marco de análisis lineal por medio del método Bi-Global de resolución del problema de valores propios en derivadas parciales. Posteriormente se propone una extensión simple para el flujo no-ortogonal del modelo polinomial de ecuaciones diferenciales ordinarias, G¨ortler-H¨ammerlin extendido, propuesto por Theofilis et al. (2003) para el flujo ortogonal, que incluye los modelos previos como casos particulares y recupera los resultados del analisis global de estabilidad lineal. Se han realizado simulaciones directas con el fin de verificar los resultados del análisis de estabilidad así como para investigar los límites de validez del modelo de flujo base utilizado. En este trabajo se ha documentado el efecto del ángulo de ataque AoA en las condiciones críticas del problema no ortogonal obteniendo que el incremento del ángulo de ataque, de AoA = 0 (flujo ortogonal) hasta valores próximos a _/2, en el cual las hipótesis sobre las que se basa el flujo base dejan de ser válidas, tiende sistemáticamente a desestabilizar el flujo. Las condiciones críticas del caso no ortogonal 0 _ AoA _ _/2 pueden recuperarse a partir del caso ortogonal mediante el uso de una transformación analítica simple que implica el ángulo de ataque AoA. Estos resultados pueden ayudar a comprender los mecanismos de desestabilización que se producen en el borde de ataque de las alas de los aviones a ángulos de ataque finitos. Como tareas pendientes quedaría realizar estudios que tengan en cuenta variaciones del campo de presión en el flujo base así como la extensión de éste al caso de flujos compresibles.

Analysis and optimization of trajectories for Ballistic Missiles Interception

Intercontinental Ballistic Missiles are capable of placing a nuclear warhead at more than 5,000 km away from its launching base. With the lethal power of a nuclear warhead a whole city could be wiped out by a single weapon causing millions of deaths. This means that the threat posed to any country from a single ICBM captured by a terrorist group or launched by a 'rogue' state is huge. This threat is increasing as more countries are achieving nuclear and advanced launcher capabilities. In order to suppress or at least reduce this threat the United States created the National Missile Defense System which involved, among other systems, the development of long-range interceptors whose aim is to destroy incoming ballistic missiles in their midcourse phase. The Ballistic Missile Defense is a high-profile topic that has been the focus of political controversy lately when the U.S. decided to expand the Ballistic Missile system to Europe, with the opposition of Russia. However the technical characteristics of this system are mostly unknown by the general public. The Interception of an ICBM using a long range Interceptor Missile as intended within the Ground-Based Missile Defense System by the American National Missile Defense (NMD) implies a series of problems of incredible complexity: - The incoming missile has to be detected almost immediately after launch. - The incoming missile has to be tracked along its trajectory with a great accuracy. - The Interceptor Missile has to implement a fast and accurate guidance algorithm in order to reach the incoming missile as soon as possible. - The Kinetic Kill Vehicle deployed by the interceptor boost vehicle has to be able to detect the reentry vehicle once it has been deployed by ICBM, when it offers a very low infrared signature, in order to perform a final rendezvous manoeuvre. - The Kinetic Kill Vehicle has to be able to discriminate the reentry vehicle from the surrounding debris and decoys. - The Kinetic Kill Vehicle has to be able to implement an accurate guidance algorithm in order to perform a kinetic interception (direct collision) of the reentry vehicle, at relative speeds of more than 10 km/s. All these problems are being dealt simultaneously by the Ground-Based Missile Defense System that is developing very complex and expensive sensors, communications and control centers and long-range interceptors (Ground-Based Interceptor Missile) including a Kinetic Kill Vehicle. Among all the technical challenges involved in this interception scenario, this thesis focuses on the algorithms required for the guidance of the Interceptor Missile and the Kinetic Kill Vehicle in order to perform the direct collision with the ICBM. The involved guidance algorithms are deeply analysed in this thesis in part III where conventional guidance strategies are reviewed and optimal guidance algorithms are developed for this interception problem. The generation of a realistic simulation of the interception scenario between an ICBM and a Ground Based Interceptor designed to destroy it was considered as necessary in order to be able to compare different guidance strategies with meaningful results. As a consequence, a highly representative simulator for an ICBM and a Kill Vehicle has been implemented, as detailed in part II, and the generation of these simulators has also become one of the purposes of this thesis. In summary, the main purposes of this thesis are: - To develop a highly representative simulator of an interception scenario between an ICBM and a Kill Vehicle launched from a Ground Based Interceptor. -To analyse the main existing guidance algorithms both for the ascent phase and the terminal phase of the missiles. Novel conclusions of these analyses are obtained. - To develop original optimal guidance algorithms for the interception problem. - To compare the results obtained using the different guidance strategies, assess the behaviour of the optimal guidance algorithms, and analyse the feasibility of the Ballistic Missile Defense system in terms of guidance (part IV). As a secondary objective, a general overview of the state of the art in terms of ballistic missiles and anti-ballistic missile defence is provided (part I).

Mies van der Rohe's Illinois Institute of Technology: Analysis and History of a Compositive Development = El IIT de Mies van der Rohe: análisis e historia de un proceso compositivo

The Illinois Institute of Technology (iit) campus, Chicago, by architect Ludwig Mies van der Rohe, is often considered as a transitional work, usually acknowledged as significant for the reorientation of his professional career after he emigrated to the United States. Moreover, its favorable recognition today is somehow indicative of its relevance as a model for urban intervention in the contemporary American city and for contemporary city planning in general, not to mention the profound impact that it had on the cityscape of Chicago. However, today we know it was rather the result of a close collaboration between he and Ludwig Hilberseimer —later on, to be completed with Alfred Caldwell— who merged their personal ideas and expertise in the design for the first time. In addition to this, when one tries to locate the design within its own historical context and evaluate the sources of its approach to it, some contradictions arise. The major impact of the images produced by Mies to promote its realization —widely disseminated in most contemporary architectural periodicals— probably outshined the particular circumstances in which the design was conceived. In fact, it would never be materialized as originally presented, but it was, instead, continuously reworked according to land availability in the site —a circumstance often ignored by subsequent architectural critic, that enthusiastically praised the design even before it was fully completed. One of the main consequences of looking at iit from such a standpoint is that, when historically contextualized, one can appreciate that, due to the urban scale of its implementation process, the design had to face a complex reality very different to that initially planned by the architect, often far from his actual possibilities of intervention. Such approach is in contradiction with the common description of the design as a ‘tabula rasa’ that allegedly would have been formulated on the basis of a full denial of its context. On the contrary, the ever-changing circumstances of the design motivated a necessary re-interpretation of the relation between its executed fragments, in order to keep the original identity of the whole in an ever-changing context. This situation implied a continuous transformation of the design by means of a steady re-composition of its elements: as the number of completed buildings increased in its successive stages, their relation to their site-specific context changed, in a very particular process that these lines try to delineate. Requiring decades to be erected, neither of its authors would ever see the design finished as planned, partially because of the difficulties in acquiring the extension of land that it required. Considering the study of this process as able to provide a valuable gateway to understand the urban discourse that the architects entailed, the aim of these lines is to analyze the problems that the iit campus design had to face. As a starting point, a relationship between practice and theory in the activity of the authors implied in iit campus design has been assumed. Far from being interrupted during World War ii, strong historical evidence can be found to infer that both were developed in parallel. Consequently, the historical sequence of the preserved testimonies has been put into context, as well as their transformation while Mies remained in charge for the campus Master Plan. Notably, when seen from this perspective, some ideas already expressed during his previous European practice were still present during the design process. Particularly, Mies's particular understanding of certain architectural concepts — such as those of ‘order’ and ‘structure’—can be traced paralleling the theories about urban planning from his collaborators, a fact that possibly facilitated the campus successful development. The study of the way these ideas were actually redeveloped and modified in the American urban context, added to the specific process of the implementation of iit campus design, sheds a new light for a critical interpretation of the reasons that made it possible, and of the actual responsibility of Mies's collaborators in its overall development and final completion. RESUMEN El campus del Illinois Institute of Technology (iit) de Chicago, obra del arquitecto Ludwig Mies van der Rohe, es a menudo considerado como una obra de transición que, por lo general, ha venido siendo reconocida como relevante para la reorientación de su carrera profesional posterior a su exilio en los Estados Unidos. El reconocimiento del que goza el proyecto es indicativo, de algún modo, de su importancia como modelo para la intervención urbana en la ciudad norteamericana contemporánea y el planeamiento de la ciudad contemporánea en general, sin olvidar el profundo impacto que ha tenido sobre el paisaje urbano de Chicago. Sin embargo, hoy sabemos que el resultado se benefició de su estrecha colaboración con Ludwig Hilberseimer y se completaría más tarde con la de Alfred Caldwell, quienes unieron sus ideas y experiencia profesional en el proyecto por primera vez. Asimismo, cuando se intenta ubicar el proyecto dentro de su propio contexto histórico y evaluar los criterios de su manera de abordarlo, surgen algunas contradicciones. El considerable impacto de las imágenes producidas por Mies para impulsar su ejecución —ampliamente difundidas en la mayoría de publicaciones de arquitectura de la época— probablemente eclipsó las particulares circunstancias en las que el proyecto fue concebido. De hecho, nunca llegó a materializarse tal y como fue inicialmente presentado. Por contra, fue reelaborado de manera continua, de acuerdo a la disponibilidad de suelo en el emplazamiento; una circunstancia a menudo ignorada por la crítica posterior, que elogió con entusiasmo el proyecto antes siquiera de que fuese terminado. Una de las principales consecuencias de contemplar el iit desde semejante punto de vista es que, una vez contextualizada históricamente su puesta en obra, se puede apreciar que el arquitecto tuvo que enfrentarse a una compleja realidad urbana muy diferente a la inicialmente prevista —probablemente debido a la escala del proyecto— a menudo lejos de sus posibilidades reales de intervención. Este enfoque contradice la descripción habitual del proyecto como una ‘tabula rasa’, que supuestamente se habría formulado sobre la base de una negación completa de su contexto. Por el contrario, las circunstancias cambiantes del proyecto obligaron una necesaria reinterpretación de la relación entre sus frag mentos ejecutados, con el fin de mantener la identidad original del conjunto en un contexto en constante cambio. Esta situación implicó una continua transformación del proyecto por medio de una permanente re-composición de sus elementos: según se incrementaba el número de edificios construidos en las etapas sucesivas de desarrollo del conjunto, variaba su relación con el contexto específico en que se emplazaban, en un proceso muy particular que estas líneas tratan de perfilar. Al necesitar décadas para ser levantado, ninguno de sus autores vería el conjunto terminado según lo planificado, en parte debido a las dificultades para la adquisición de la extensión de suelo que demandaba. Asumiendo que el estudio de este proceso es capaz de proporcionar una valiosa puerta de entrada para elucidar el discurso urbano asumido por los Mies, el objetivo de estas líneas es analizar los problemas a los que el proyecto del campus del iit tuvo que enfrentarse. Como punto de partida, se ha supuesto una relación entre la práctica y la teoría en la actividad de los autores implicados en el proyecto del campus del iit. Lejos de interrumpirse durante la Segunda Guerra Mundial, existen evidencias históricas sólidas para deducir que ambas vertientes se desarrollaron en paralelo. En consecuencia, se ha contextualizado la secuencia histórica de los testimonios conservados, así como su transformación durante el periodo en que Mies estuvo a cargo del Plan General del campus. Significativamente, al ser contempladas bajo esta perspectiva, algunas ideas ya expresadas durante su práctica europea anterior resultan aún presentes durante la redacción del proyecto. En concreto, se puede trazar un paralelismo entre la comprensión particular de Mies de ciertos conceptos arquitectónicos —como los de ‘orden’ y ‘estructura’— y las teorías sobre el urbanismo de sus colaboradores, hecho que posiblemente facilitó el exitoso desarrollo del proyecto. El estudio de la manera en que estas ideas fueron reelaboradas y modificadas en el contexto urbano estadounidense, sumado al proceso específico de su aplicación en el proyecto del campus del iit, arroja una nueva luz para una interpretación crítica tanto de las razones que lo hicieron posible, como del papel real que los colaboradores de Mies tuvieron en su desarrollo y ejecución final.

Development of Efficient Techniques for the Analysis and Design of Antennas in Dual-Reflectarray Configuration

This thesis contributes to the analysis and design of printed reflectarray antennas. The main part of the work is focused on the analysis of dual offset antennas comprising two reflectarray surfaces, one of them acts as sub-reflector and the second one acts as mainreflector. These configurations introduce additional complexity in several aspects respect to conventional dual offset reflectors, however they present a lot of degrees of freedom that can be used to improve the electrical performance of the antenna. The thesis is organized in four parts: the development of an analysis technique for dualreflectarray antennas, a preliminary validation of such methodology using equivalent reflector systems as reference antennas, a more rigorous validation of the software tool by manufacturing and testing a dual-reflectarray antenna demonstrator and the practical design of dual-reflectarray systems for some applications that show the potential of these kind of configurations to scan the beam and to generate contoured beams. In the first part, a general tool has been implemented to analyze high gain antennas which are constructed of two flat reflectarray structures. The classic reflectarray analysis based on MoM under local periodicity assumption is used for both sub and main reflectarrays, taking into account the incident angle on each reflectarray element. The incident field on the main reflectarray is computed taking into account the field radiated by all the elements on the sub-reflectarray.. Two approaches have been developed, one which employs a simple approximation to reduce the computer run time, and the other which does not, but offers in many cases, improved accuracy. The approximation is based on computing the reflected field on each element on the main reflectarray only once for all the fields radiated by the sub-reflectarray elements, assuming that the response will be the same because the only difference is a small variation on the angle of incidence. This approximation is very accurate when the reflectarray elements on the main reflectarray show a relatively small sensitivity to the angle of incidence. An extension of the analysis technique has been implemented to study dual-reflectarray antennas comprising a main reflectarray printed on a parabolic surface, or in general in a curved surface. In many applications of dual-reflectarray configurations, the reflectarray elements are in the near field of the feed-horn. To consider the near field radiated by the horn, the incident field on each reflectarray element is computed using a spherical mode expansion. In this region, the angles of incidence are moderately wide, and they are considered in the analysis of the reflectarray to better calculate the actual incident field on the sub-reflectarray elements. This technique increases the accuracy for the prediction of co- and cross-polar patterns and antenna gain respect to the case of using ideal feed models. In the second part, as a preliminary validation, the proposed analysis method has been used to design a dual-reflectarray antenna that emulates previous dual-reflector antennas in Ku and W-bands including a reflectarray as subreflector. The results for the dualreflectarray antenna compare very well with those of the parabolic reflector and reflectarray subreflector; radiation patterns, antenna gain and efficiency are practically the same when the main parabolic reflector is substituted by a flat reflectarray. The results show that the gain is only reduced by a few tenths of a dB as a result of the ohmic losses in the reflectarray. The phase adjustment on two surfaces provided by the dual-reflectarray configuration can be used to improve the antenna performance in some applications requiring multiple beams, beam scanning or shaped beams. Third, a very challenging dual-reflectarray antenna demonstrator has been designed, manufactured and tested for a more rigorous validation of the analysis technique presented. The proposed antenna configuration has the feed, the sub-reflectarray and the main-reflectarray in the near field one to each other, so that the conventional far field approximations are not suitable for the analysis of such antenna. This geometry is used as benchmarking for the proposed analysis tool in very stringent conditions. Some aspects of the proposed analysis technique that allow improving the accuracy of the analysis are also discussed. These improvements include a novel method to reduce the inherent cross polarization which is introduced mainly from grounded patch arrays. It has been checked that cross polarization in offset reflectarrays can be significantly reduced by properly adjusting the patch dimensions in the reflectarray in order to produce an overall cancellation of the cross-polarization. The dimensions of the patches are adjusted in order not only to provide the required phase-distribution to shape the beam, but also to exploit the crosses by zero of the cross-polarization components. The last part of the thesis deals with direct applications of the technique described. The technique presented is directly applicable to the design of contoured beam antennas for DBS applications, where the requirements of cross-polarisation are very stringent. The beam shaping is achieved by synthesithing the phase distribution on the main reflectarray while the sub-reflectarray emulates an equivalent hyperbolic subreflector. Dual-reflectarray antennas present also the ability to scan the beam over small angles about boresight. Two possible architectures for a Ku-band antenna are also described based on a dual planar reflectarray configuration that provides electronic beam scanning in a limited angular range. In the first architecture, the beam scanning is achieved by introducing a phase-control in the elements of the sub-reflectarray and the mainreflectarray is passive. A second alternative is also studied, in which the beam scanning is produced using 1-bit control on the main reflectarray, while a passive subreflectarray is designed to provide a large focal distance within a compact configuration. The system aims to develop a solution for bi-directional satellite links for emergency communications. In both proposed architectures, the objective is to provide a compact optics and simplicity to be folded and deployed.

Adverse aerodynamics effects of a high speed train under the influence of cross winds, analysis and optimization of wind fence

The research work that here is summarized, it is classed on the area of dynamics and measures of railway safety, specifically in the study of the influence of the cross wind on the high-speed trains as well as the study of new mitigation measures like wind breaking structures or wind fences, with optimized shapes. The work has been developed in the Research Center in Rail Technology (CITEF), and supported by the Universidad Politécnica de Madrid, Spain.

Normalización del análisis de la piedra y conservación del patrimonio cultural. The Standardization of Stone Analysis and Conservation of Cultural Heritage

La normalización de los métodos de análisis y de los principales aspectos relacionados con la conservación de los bienes culturales ha empezado en 2004 con la creación del comité europeo de normalización, CEN/TC 346 Conservation of Cultural Property, que tiene la responsabilidad no solamente de redactar protocolos de ensayos en laboratorio, sino también proponer las recomendaciones más adecuadas para designarlos de forma consensual y conservarlos de la forma más apropiada. Se comentan los aspectos relacionados con el origen de estas normas, el trabajo desarrollado y que muchas de ellas, aunque no estén dirigidas específicamente a la piedra, tienen en cuenta la presencia de este material en objetos arqueológicos, obras de arte, estructuras de fábricas y elementos ornamentales.

Analysis and design of a thrombectomy device by using simulation techniques

Purpose: In this work, we present the analysis, design and optimization of one experimental device recently developed in the UK, called the 'GP' Thrombus Aspiration Device (GPTAD). This device has been designed to remove blood clots without the need to make contact with the clot itself thereby potentially reducing the risk of problems such as downstream embolisation. Method: To obtain the minimum pressure necessary to extract the clot and to optimize the device, we have simulated the performance of the GPTAD analysing the resistances, compliances and inertances effects. We model a range of diameters for the GPTAD considering different forces of adhesion of the blood clot to the artery wall, and different lengths of blood clot. In each case we determine the optimum pressure required to extract the blood clot from the artery using the GPTAD, which is attached at its proximal end to a suction pump. Result: We then compare the results of our mathematical modelling to measurements made in laboratory using plastic tube models of arteries of comparable diameter. We use abattoir porcine blood clots that are extracted using the GPTAD. The suction pressures required for such clot extraction in the plastic tube models compare favourably with those predicted by the mathematical modelling. Discussion & Conclusion: We conclude therefore that the mathematical modelling is a useful technique in predicting the performance of the GPTAD and may potentially be used in optimising the design of the device.

Analysis and optimization of propagation losses in LiNbO3 optical waveguides produced by swift heavy-ion irradiation

The propagation losses (PL) of lithium niobate optical planar waveguides fabricated by swift heavy-ion irradiation (SHI), an alternative to conventional ion implantation, have been investigated and optimized. For waveguide fabrication, congruently melting LiNbO3 substrates were irradiated with F ions at 20 MeV or 30 MeV and fluences in the range 1013–1014 cm−2. The influence of the temperature and time of post-irradiation annealing treatments has been systematically studied. Optimum propagation losses lower than 0.5 dB/cm have been obtained for both TE and TM modes, after a two-stage annealing treatment at 350 and 375∘C. Possible loss mechanisms are discussed.

Analysis and comparison of the national and regional emission inventories for the Greater Madrid Region through air quality simulations

Este trabajo presenta un análisis y una metodología para la armonización de inventarios de emisiones utilizados en modelos de calidad del aire.

A generic framework for the analysis and specialization of kogic programs

The relationship between abstract interpretation [2] and partial evaluation [5] has received considerable attention and (partial) integrations have been proposed starting from both the partial deduction (see e.g. [6] and its references) and abstract interpretation perspectives. Abstract interpretation-based analyzers (such as the CiaoPP analyzer [9,4]) generally compute a program analysis graph [1] in order to propagate (abstract) call and success information by performing fixpoint computations when needed. On the other hand, partial deduction methods [7] incorporate powerful techniques for on-line specialization including (concrete) call propagation and unfolding.

A generic framework for the analysis and specialization of logic programs

The relationship between abstract interpretation and partial deduction has received considerable attention and (partial) integrations have been proposed starting from both the partial deduction and abstract interpretation perspectives. In this work we present what we argüe is the first fully described generic algorithm for efñcient and precise integration of abstract interpretation and partial deduction. Taking as starting point state-of-the-art algorithms for context-sensitive, polyvariant abstract interpretation and (abstract) partial deduction, we present an algorithm which combines the best of both worlds. Key ingredients include the accurate success propagation inherent to abstract interpretation and the powerful program transformations achievable by partial deduction. In our algorithm, the calis which appear in the analysis graph are not analyzed w.r.t. the original definition of the procedure but w.r.t. specialized definitions of these procedures. Such specialized definitions are obtained by applying both unfolding and abstract executability. Our framework is parametric w.r.t. different control strategies and abstract domains. Different combinations of such parameters correspond to existing algorithms for program analysis and specialization. Simultaneously, our approach opens the door to the efñcient computation of strictly more precise results than those achievable by each of the individual techniques. The algorithm is now one of the key components of the CiaoPP analysis and specialization system.

Some issues in analysis and specialization of modular ciao-prolog programs

Separating programs into modules is a well-known technique which has proven very useful in program development and maintenance. Starting by introducing a number of possible scenarios, in this paper we study different issues which appear when developing analysis and specialization techniques for modular logic programming. We discuss a number of design alternatives and their consequences for the different scenarios considered and describe where applicable the decisions made in the Ciao system analyzer and specializer. In our discussion we use the module system of Ciao Prolog. This is both for concreteness and because Ciao Prolog is a second-generation Prolog system which has been designed with global analysis and specialization in mind, and which has a strict module system. The aim of this work is not to provide a theoretical basis on modular analysis and specialization, but rather to discuss some interesting practical issues.

Analysis and design of multiagent systems using MAS-CommonKADS

This article proposes an agent-oriented methodology called MAS-CommonKADS and develops a case study. This methodology extends the knowledge engineering methodology CommonKADSwith techniquesfrom objectoriented and protocol engineering methodologies. The methodology consists of the development of seven models: Agent Model, that describes the characteristics of each agent; Task Model, that describes the tasks that the agents carry out; Expertise Model, that describes the knowledge needed by the agents to achieve their goals; Organisation Model, that describes the structural relationships between agents (software agents and/or human agents); Coordination Model, that describes the dynamic relationships between software agents; Communication Model, that describes the dynamic relationships between human agents and their respective personal assistant software agents; and Design Model, that refines the previous models and determines the most suitable agent architecture for each agent, and the requirements of the agent network.

Seed image analysis and taxonomy of Diplotaxis DC. (Brassicaceae, Brassiceae)

The genus Diplotaxis, comprising 32 or 34 species, plus several additional infraspecific taxa, displays a considerable degree of heterogeneity in the morphology, molecular markers, chromosome numbers and geographical amplitude of the species. The taxonomic relationships within the genus Diplotaxis were investigated by phenetic characterisation of germplasm belonging to 27 taxa of the genus, because there is an increasing interest in Diplotaxis, since some of its species (D. tenuifolia, D. muralis) are gathered or cultivated for human consumption, whereas others are frequent arable weeds (D. erucoides) in many European vineyards. Using a computer-aided vision system, 33 morpho-colorimetric features of seeds were electronically measured. The data were used to implement a statistical classifier, which is able to discriminate the taxa within the genus Diplotaxis, in order to compare the resulting species grouping with the current infrageneric systematics of this genus. Despite the high heterogeneity of the samples, due to the great intra-population variability, the stepwise Linear Discriminant Analysis method, applied to distinguish the groups, was able to reach over 80% correct identification. The results obtained allowed us to confirm the current taxonomic position of most taxa and suggested the taxonomic position of others for reconsideration.