The use of terms such as “Engineering Systems”, “System of systems” and others have been coming into greater use over the past decade to denote systems of importance but with implied higher complexity than for the term systems alone. This paper searches for a useful taxonomy or classification scheme for complex Systems. There are two aspects to this problem: 1) distinguishing between Engineering Systems (the term we use) and other Systems, and 2) differentiating among Engineering Systems. Engineering Systems are found to be differentiated from other complex systems by being human-designed and having both significant human complexity as well as significant technical complexity. As far as differentiating among various engineering systems, it is suggested that functional type is the most useful attribute for classification differentiation. Information, energy, value and mass acted upon by various processes are the foundation concepts underlying the technical types. / Engineering Systems Division and Mechanical Engineering, Center for Innovation in Product Development

In view of the fact that a same complex phenomenon can be approached by different conceptual frameworks, it is natural to inquire on the possibility to find connections between different types of quantities, such as topological, dynamical, statistical or thermodynamical, characterizing the same system. The present work is built on the idea that this line of approach can provide interesting insights on possible universal principles governing complex phenomena. In Chapter I we introduce concepts and tools of dynamical systems and thermodynamics as applied in macroscopic scale description as well as, for a later use, a number of selected representative models. In Chapter II we briefly present the elements of the theory of Markov processes describing a large class of stochastic process and also introduce some important concepts on the probabilistic description of deterministic systems. This chapter ends with a thermodynamic formulation accounting for the evolution of the entropy under the effect of stochastic fluctuations. In Chapter III, after introducing the main concepts and recent advances in network theory, we provide a connection between dynamical systems and network theory, which shows how universal structural properties of evolving networks can arise from deterministic dynamics. More specifically, we show explicitly the relation between the connectivity patterns of these networks and the indicators of the underlying dynamics, such as the local Lyapunov exponents. Our analysis is applied to representative models of chaotic maps, chaotic flows and is finally extended to stochastic processes. In Chapter IV we address the inverse problem, namely, processes whose dynamics is determined, in part, by the structure of the network in which they are embedded. In particular, we focus on systems of particles diffusing on a lattice and reacting instantaneously upon encountering each other. We study the role of the topology, the degree of synchronicity of motion and the reaction mechanism on the efficiency of the process. This lead us to identify a common generic mechanism responsible for the behavior of the efficiency, as a function of the control parameters. Finally, in Chapter V we study the connection between the topology and the thermodynamic properties of reaction networks, with focus on the entropy production and the system’s efficiency at nonequilibrium steady states. We also explore the connection between dynamic and thermodynamic properties of nonlinear feedbacks, as well as the response properties of reaction networks against both deterministic and stochastic external perturbations. We address networks of varying topologies, from regular lattices to complex structures./Le présent travail s’inscrit dans le domaine de recherche sur les systèmes complexes. Différentes approches, basées des systèmes dynamiques, de la thermodynamique des systèmes hors d’équilibre, de la physique statistique et, plus récemment, de la théorie des réseaux, sont combinés afin d’explorer des liens entre différentes types de grandeurs qui caractérisent certaines classes de comportements complexes. Dans le Chapitre I nous introduisons les principaux concepts et outils de systèmes dynamiques et de thermodynamique. Dans le Chapitre II nous présentons premièrement des éléments de la théorie de processus de Markov, ainsi que les concepts à la base de la description probabiliste des systèmes déterministes. Nous finissons le chapitre en proposant une formulation thermodynamique qui décrit l’évolution de l’entropie hors d’équilibre, soumis à l’influence de fluctuations stochastiques. Dans le Chapitre III nous introduisons les concepts de base en théorie des réseaux, ainsi qu’un résumé générale des progrès récents dans le domaine. Nous établissons ensuite une connexion entre la théorie des systèmes dynamiques et la théorie de réseaux. Celle-ci permet d’approfondir la compréhension des mécanismes responsables de l’émergence des propriétés structurelles dans des réseaux crées par des lois dynamiques déterministes. En particulier, nous mettons en évidence la relation entre des motifs de connectivité de ce type de réseaux et des indicateurs de la dynamique sous-jacente, tel que des exposant de Lyapounov locaux. Notre analyse est illustrée par des applications et des flots chaotiques et étendue à des processus stochastiques. Dans le Chapitre IV nous étudions le problème complémentaire, à savoir, celui de processus dont la dynamique est déterminée, en partie, par la structure du réseau dans lequel elle se déroule. Plus précisément, nous nous concentrons sur le cas de systèmes de particules réactives, diffusent au travers d’un réseau et réagissant instantanément lorsqu’un rencontre se produit entre elles. Nous étudions le rôle de la topologie, du degré de synchronicité des mouvements et aussi celui du mécanisme de réaction sur l’efficacité du processus. Dans les différents modèles étudiés, nous identifions un mécanisme générique commun, responsable du comportement de l’efficacité comme fonction des paramètres de contrôle. Enfin, dans le Chapitre V nous abordons la connexion entre la topologie et les propriétés thermodynamiques des réseaux de réactions, en analysant le comportement local et global de la production d’entropie et l’efficacité du système dans des état stationnaires de non-équilibre. Nous explorons aussi la connexion entre la dynamique et les propriétés de boucles de rétroaction non linéaires, ainsi que les propriétés de réponse des réseaux de réaction à des perturbations stochastiques et déterministes externes. Nous considérons le cas de réseaux à caractère régulier aussi bien que celui de réseaux complexes.

Humanity is facing a series of challenges, including climate change, biodiversity loss, decreasing availability of cheap fossil fuel energy and social inequality that, when taken together, constitute a sustainability crisis. Agricultural systems are vitally important for the survival of humanity and must be moved towards greater sustainability. In Vietnam, the challenges facing the agriculture sector are immediate and pressing. These challenges include the need to improve the livelihoods of millions of smallholder farmers, improve food safety and protect already heavily burdened ecosystems. In response to these challenges, a number of alternative agriculture approaches, including safe vegetable production and organic farming have emerged. While the use of chemical fertilizers and pesticides are not permitted in certified organic agriculture, the requirements for safe vegetable production are not nearly as stringent. Chemical fertilizers and some low toxicity pesticides are allowed in safe vegetable production as long as pesticide residues are below proscribed limits. This research assesses the contributions that safe vegetable production and organic agriculture are making to the development of more sustainable agroecosystems in Vietnam. Organic production is still in early stages of development, with the majority of the projects directed towards production for export. Safe vegetables in contrast are produced primarily for the domestic market and demand is driven by consumer concerns over excessive pesticide use in conventional vegetable production. A sustainability assessment that explores the effect that safe vegetable production is having on eight major criteria for sustainability is applied in Cu Chi District, Ho Chi Minh City. Research methods included semi-structured interviews and group discussions with safe vegetable farmers together with interviews of other key actors from the agricultural sector in Vietnam. Along with the goal of protecting human health, farmers are interested in safe vegetable production because of improved economic returns made possible by reduced inputs and greater market access. While safe vegetable production is contributing to greater agroecosystem sustainability, further improvements are needed in some areas, specifically in the use of agrochemicals. There are encouraging signs in relation to pesticides, with some farmers reducing their pesticide use and moving towards less-toxic pesticides. Further movement towards sustainability could be fostered by a shift to the use of pesticides only as a last resort, a further shift from chemical to organic fertilizers, and improved capacity of farmers to experiment with and adapt safe vegetable production techniques.

Business intelligence has fundamentally changed how many companies conduct their business. The focus of academic literature has however been on volume-operation companies that provide services to millions of customers. Complex-systems companies have fewer customers and pursue customer needs by providing more customized products and services. The knowledge in the research society is limited to volume-operation companies and there a need for more case studies regarding how companies actually use their information systems, specifically complex-systems companies. This work looks at a case of a complex-systems company with the overall aim to see how complex-systems companies may take advantage of business intelligence. A framework was used to measure BI maturity; expressed future needs were compared to future trends in BI literature and BI usage in specific areas was analyzed with the help of a framework from BI literature. The results indicate that the company is somewhere between Aspirational and Experienced with respect to BI maturity. BI is used for reporting a variety of key performance indicators and the main analysis tool for various calculations is Excel. The expressed future needs are mainly strategy-driven and technology-driven and often involve better and faster access to information. The difference in the business models of volume-operations companies and complex-systems companies could influence the BI maturity and help to explain the maturity difference between these two types of companies. Furthermore, the results indicate that there is a difference between the roles of BI tools in complex-systems companies compared to volume-operations.

Humanity is facing a series of challenges, including climate change, biodiversity loss, decreasing availability of cheap fossil fuel energy and social inequality that, when taken together, constitute a sustainability crisis. Agricultural systems are vitally important for the survival of humanity and must be moved towards greater sustainability. In Vietnam, the challenges facing the agriculture sector are immediate and pressing. These challenges include the need to improve the livelihoods of millions of smallholder farmers, improve food safety and protect already heavily burdened ecosystems. In response to these challenges, a number of alternative agriculture approaches, including safe vegetable production and organic farming have emerged. While the use of chemical fertilizers and pesticides are not permitted in certified organic agriculture, the requirements for safe vegetable production are not nearly as stringent. Chemical fertilizers and some low toxicity pesticides are allowed in safe vegetable production as long as pesticide residues are below proscribed limits. This research assesses the contributions that safe vegetable production and organic agriculture are making to the development of more sustainable agroecosystems in Vietnam. Organic production is still in early stages of development, with the majority of the projects directed towards production for export. Safe vegetables in contrast are produced primarily for the domestic market and demand is driven by consumer concerns over excessive pesticide use in conventional vegetable production. A sustainability assessment that explores the effect that safe vegetable production is having on eight major criteria for sustainability is applied in Cu Chi District, Ho Chi Minh City. Research methods included semi-structured interviews and group discussions with safe vegetable farmers together with interviews of other key actors from the agricultural sector in Vietnam. Along with the goal of protecting human health, farmers are interested in safe vegetable production because of improved economic returns made possible by reduced inputs and greater market access. While safe vegetable production is contributing to greater agroecosystem sustainability, further improvements are needed in some areas, specifically in the use of agrochemicals. There are encouraging signs in relation to pesticides, with some farmers reducing their pesticide use and moving towards less-toxic pesticides. Further movement towards sustainability could be fostered by a shift to the use of pesticides only as a last resort, a further shift from chemical to organic fertilizers, and improved capacity of farmers to experiment with and adapt safe vegetable production techniques.

Spatio-temporal systems with heterogeneity in their structure and behavior have two major problems. The first one is that such systems extend over very large spatial and temporal domains and consume a lot of resources to simulate that they are infeasible to study with current platforms. The second one is that the data available for understanding such systems is limited. This also makes it difficult to get the data for validation of their constituent processes while simultaneously considering their global behavior. For example, the valley fever fungus considered in this dissertation is spread over a large spatial grid in the arid Southwest and typically needs to be simulated over several decades of time to obtain useful information. It is also hard to get the temperature and moisture data at every grid point of the spatial domain over the region of study. In order to address the first problem, we develop a method based on the discrete event system specification which exploits the heterogeneity in the activity of the spatio-temporal system and which has been shown to be effective in solving relatively simple partial differential equation systems. The benefit of addressing the first problem is that it now makes it feasible to address the second problem.We address the second problem by making use of a multilevel methodology based on modeling and simulation and systems theory. This methodology helps us in the construction of models with different resolutions (base and lumped models). This allows us to refine an initially constructed lumped model with detailed physics-based process models and assess whether they improve on the original lumped models. For that assessment, we use the concept of experimental frame to delimit where the improvement is needed. This allows us to work with the available data, improve the component models in their own experimental frame and then move them to the overall frame. In this dissertation, we develop a multilevel methodology and apply it to a valley fever model. Moreover, we study the model's behavior in a particular experimental frame of interest, namely the formation of new sporing sites.

Seguint una concepció clàssica de la Intel•ligència Artificial (aquella que es posava com horitzó una definició dels mecanismes cognitius i la seva implementació en computadors), aquesta tesi s'endinsa en el problema de l'organització del coneixement. En especial, es posa atenció a la memòria semàntica i el coneixement lingüístic, intentant esbrinar de quina forma emergeixen les relacions semàntiques entre paraules. Per assolir aquests objectius es recorre a tres fonts principals: la utilització de dades empíriques provinents de la psicolingüística i la neuropsicologia; l'ús de la metodologia de sistemes complexes (física estadística) per la construcció de models i simulació de dinàmiques; i finalment l'aprofitament de les tecnologies al nostre abast tant per l'obtenció de noves dades (Internet) com una capacitat d'emmagatzemament suficient i velocitat de processament per al tractament de dades massives. D'aquest punt de vista arrelat en la Ciència Cognitiva en poden sorgir aplicacions fortament vinculades a problemes vigents en l'àmbit de Ciències de la Computació, com són l'extracció d'informació no supervisada, l'enriquiment de bases de dades i recursos lingüístics electrònics (Wikipedia, WordNet, etc.) i la millora de sistemes de consulta (query-based systems). Al Capítol 2 s'estableixen les bases metodològiques que han servit per construir la resta del treball. El Capítol 3 es dedica a aclarir (i) quina mena de dades s'han emprat (i s'empren) en l'estudi a gran escala del llenguatge i els fenòmens cognitius que l'envolten; i (ii) es revisen els treballs més destacables que s'han fet fins al moment actual al voltant del llenguatge i la cognició. Al Capítol 4 s'introdueix el Random Inheritance Model, que representa un intent per comprendre com emergeixen la similitud semàntica entre paraules i les categories semàntiques. Els resultats es comparen amb dades empíriques basades en les respostes de subjectes humans. Al Capítol 5 presentem un model de degradació semàntica que emula processos neurodegeneratius i prediu acuradament, a nivell qualitatiu, les observacions experimentals amb malalts d'Alzheimer que s'han fet en l'àmbit de la neuropsicologia. En aquests processos degeneratius convergeixen interessos multidisciplinars, que van de la mateixa cognició al fenomen de percolació en física estadística. El Capítol 6 queda finalment dedicat a una reflexió global d'aquesta memòria. / Following a classical conception of Artificial Intelligence (one that aims a definition of cognitive mechanisms and their implementation in computers), this thesis explores the problem of knowledge organization. In particular, it draws attention to the linguistic and semantic memory, trying to find out how semantic relations emerge between words. To achieve these objectives, we rely on three main sources: use of empirical data from psycholinguistics and neuropsychology; the use of complex systems (statistical physics) methodology to build and simulate dynamic models; and finally the utilization of technologies at our disposal both for obtaining new data (Internet) as well as sufficient storage capacity and processing speed for massive data manipulation. From this point of view, rooted in Cognitive Science, many applications may arise, some of them strongly linked to current problems in the field of Computer Science, such as unsupervised information extraction, enrichment of databases and language electronic resources (Wikipedia, WordNet, etc.). and improve consultation systems (query-based systems). In Chapter 2 the methodologies that have helped build the rest of the work are established. Chapter 3 is devoted to clarify (i) the kind of data that have been used in the large-scale study of language and cognitive phenomena around it, and (ii) review some of the major contributions to the date about language and cognition. In Chapter 4 the Random Inheritance Model is introduced, which represents an attempt to understand how does semantic similarity between words and semantic categories emerge. Results are compared with empirical data obtained from responses with human subjects. In Chapter 5 we present a model of semantic degradation which emulates neurodegenerative processes, and predicts experimental observations from Alzheimer's Disease patients in the field of neuropsychology. In the study of such degenerative processes different multidisciplinary interests converge, ranging from cognition itself to percolation theory in statistical physics. Chapter 6 is finally devoted to a global reflection of this memory.

This paper provides an overview on the evolutionary theory of the firm. The specific feature of the evolutionary approach is that it explains the adaptive behaviors of firms through the tension between innovation and selection. It is suggested that the evolutionary theory can provide a useful basis for a theory of the firm which is concerned with change over time and development. (author's abstract) / Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"

The aim of this thesis is to provide a modelling approach and simulation framework that allows for emergent dynamics in multi-nephron systems to be studied. The ultimate intent of this research is to provide an approach to renal modelling that is capable of predicting whole-kidney function from the dynamics of individual nephrons, and can therefore be of practical use to clinicians. The contributions of this thesis are: / • A modelling approach—hierarchical dynamical networks—which combines complex networks and graph automata into a single modelling framework. This approach explicitly captures the structure and interactions in multi-nephron systems, and decouples the structure and behaviour of the model. This approach allows emergent dynamics to be easily explored and analysed. / • The development of a multi-nephron model that produces valid behaviour and renders the simulation of whole-kidney function from the dynamics of individual nephrons computationally tractable. Using this model, the emergent effects of the couplings and interactions between nephrons can be investigated. / • An investigation into the dynamics of multi-nephron systems that focuses on whole-system and hierarchical properties rather than the dynamics of individual nephrons. As part of this investigation, the dynamics of a 72-nephron system are analysed—a system significantly larger than existing multi-nephron models. / • A study of whole-system stability in response to localised impairments in nephron function. This is the first study of the emergent dynamics of impaired nephron function, and serves as an illustration of how the emergent dynamics produced by renal diseases may be predicted and analysed. The impaired multinephron systems are shown to exhibit very stable behaviour, which we contend is a feature of both the model and the kidney proper. / • The computational cost of the model is shown to be low enough that the simulation of whole-kidney function is feasible for the first time. It is also demonstrated that simulations can be easily distributed across multiple computers, resulting in a significant gain in performance. An implementation of the model that supports parallel and distributed execution is presented, based on the Join Calculus. / • In order to predict whole-kidney function, a whole-kidney model must be constructed. This thesis proposes two approaches for automatically generating such models. / I conclude that the modelling and analysis techniques presented in this thesis allow for emergent dynamics to be studied in large multinephron systems. This work demonstrates that, for the first time, simulation of whole-kidney function from the dynamics of individual nephrons is tractable. Furthermore, the work provides a basis for predicting emergent effects of localised renal disease. With the continued development of this model, we hope that significant insight will be gained into the onset, progression and treatment of renal diseases.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Mary F. Wheeler. Vita. Includes bibliographical references. Also available from UMI.