Modularity and anti-modularity in networks with arbitrary degree distribution

Networks describing the interaction of the elements that constitute a complex system grow and develop via a number of different mechanisms, such as the addition and deletion of nodes, the addition and deletion of edges, as well as the duplication or fusion of nodes. While each of these mechanisms can have a different cause depending on whether the network is biological, technological, or social, their impact on the network's structure, as well as its local and global properties, is similar. This allows us to study how each of these mechanisms affects networks either alone or together with the other processes, and how they shape the characteristics that have been observed. We study how a network's growth parameters impact the distribution of edges in the network, how they affect a network's modularity, and point out that some parameters will give rise to networks that have the opposite tendency, namely to display anti-modularity. Within the model we are describing, we can search the space of possible networks for parameter sets that generate networks that are very similar to well-known and well-studied examples, such as the brain of a worm, and the network of interactions of the proteins in baker's yeast.Comment: 23 pages. 13 figures, 1 table. Includes Supplementary tex

Sustaining Glasgow's Urban Networks: the Link Communities of Complex Urban Systems

As cities grow in population size and became more crowded (UN DESA, 2018), the main future challenges around the world will remain to be accommodating the growing urban population while drastically reducing environmental pressure. Contemporary urban agglomerations (large or small) constantly impose burden on the natural environment by conveying ecosystem services to close and distant places, through coupled human nature [infrastructure] systems (CHANS). Tobler’s first law in geography (1970) that states that “everything is related to everything else, but near things are more related than distant things” is now challenged by globalization. When this law was first established, the hypothesis referred to geological processes (Campbell and Shin, 2012, p.194) that were predominantly observed in pre-globalized economy, where freight was costly and mainly localized (Zhang et al., 2018). With the recent advances and modernisation made in transport technologies, most of them in the sea and air transportation (Zhang et al., 2018) and the growth of cities in population, natural resources and bi-products now travel great distances to infiltrate cities (Neuman, 2006) and satisfy human demands. Technical modernisation and the global hyperconnectivity of human interactions and trading, in the last thirty years alone resulted with staggering 94 per cent growth of resource extraction and consumption (Giljum et al., 2015). Local geographies (Kennedy, Cuddihy and Engel-Yan, 2007) will remain affected by global urbanisation (Giljum et al., 2015), and as a corollary, the operational inefficiencies of their local infrastructure networks, will contribute even more to the issues of environmental unsustainability on a global scale. Another challenge for future city-regions is the equity of public infrastructure services and policy creation that promote the same (Neuman and Hull, 2009). Public infrastructure services refer to services provisioned by networked infrastructure, which are subject to both public obligation and market rules. Therefore, their accessibility to all citizens needs to be safeguarded. The disparity of growth between networked infrastructure and socio-economic dynamics affects the sustainable assimilation and equal access to infrastructure in various districts in cities, rendering it as a privilege. Yet, the empirical evidence of whether the place of residence acts as a disadvantage to public service access and use, remains rather scarce (Clifton et al., 2016). The European Union recognized (EU, 2011) the issue of equality in accessibility (i.e. equity) critical for territorial cohesion and sustainable development across districts, municipalities and regions with diverse economic performance. Territorial cohesion, formally incorporated into the Treaty of Lisbon, now steers the policy frameworks of territorial development within the Union. Subsequently, the European Union developed a policy paradigm guided by equal access (Clifton et al., 2016) to public infrastructure services, considering their accessibility as instrumental aspect in achieving territorial cohesion across and within its member states. A corollary of increasing the equity to public infrastructure services among growing global population is the potential increase in environmental pressure they can impose, especially if this pressure is not decentralised and surges at unsustainable rate (Neuman, 2006). This danger varies across countries and continents, and is directly linked to the increase of urban population due to; [1] improved quality of life and increased life expectancy and/or [2] urban in-migration of rural population and/or [3] global political or economic immigration. These three rising urban trends demand new approaches to reimagine planning and design practices that foster infrastructure equity, whilst delivering environmental justice. Therefore, this research explores in depth the nature of growth of networked infrastructure (Graham and Marvin, 2001) as a complex system and its disparity from the socio-economic growth (or decline) of Glasgow and Clyde Valley city-region. The results of this research gain new understanding in the potential of using emerging tools from network science for developing optimization strategy that supports more cecentralized, efficient, fair and (as an outcome) sustainable enlargement of urban infrastructure, to accommodate new and empower current residents of the city. Applying the novel link clustering community detection algorithm (Ahn et al., 2010) in this thesis I have presented the potential for better understanding the complexity behind the urban system of networked infrastructure, through discovering their overlapping communities. As I will show in the literature review (Chapter 2), the long standing tradition of centralised planning practice relying on zoning and infiltrating infrastructure, left us with urban settlements which are failing to respond to the environmental pressure and the socio-economic inequalities. Building on the myriad of knowledge from planners, geographers, sociologists and computer scientists, I developed a new element (i.e. link communities) within the theory of urban studies that defines cities as complex systems. After, I applied a method borrowed from the study of complex networks to unpack their basic elements. Knowing the link (i.e. functional, or overlapping) communities of metropolitan Glasgow enabled me to evaluate the current level of communities interconnectedness and reveal the gaps as well as the potentials for improving the studied system’s performance. The complex urban system in metropolitan Glasgow was represented by its networked infrastructure, which essentially was a system of distinct sub-systems, one of them mapped by a physical and the other one by a social graph. The conceptual framework for this methodological approach was formalised from the extensively reviewed literature and methods utilising network science tools to detect community structure in complex networks. The literature review led to constructing a hypothesis claiming that the efficiency of the physical network’s topology is achieved through optimizing the number of nodes with high betweenness centrality, while the efficiency of the logical network’s topology is achieved by optimizing the number of links with high edge betweenness. The conclusion from the literature review presented through the discourse on to the primal problem in 7.4.1, led to modelling the two network topologies as separate graphs. The bipartite graph of their primal syntax was mirrored to be symmetrical and converted to dual. From the dual syntax I measured the complete accessibility (i.e. betweenness centrality) of the entire area and not only of the streets. Betweenness centrality of a node measures the number of shortest paths that pass through the node connecting pairs of nodes. The betweenness centrality is same as the integration of streets in space syntax, where the streets are analysed in their dual syntax representation. Street integration is the number of intersections the street shares with other streets and a high value means high accessibility. Edges with high betweenness are shared between strong communities. Based on the theoretical underpinnings of the network’s modularity and community structure analysed herein, it can be concluded that a complex network that is both robust and efficient (and in urban planning terminology ‘sustainable’) is consisted of numerous strong communities connected with each other by optimal number of links with high edge betweenness. To get this insight, the study detected the edge cut-set and vertex cut-set of the complex network. The outcome was a statistical model developed in the open source software R (Ihaka and Gentleman, 1996). The model empirical detects the network’s overlapping communities, determining the current sustainability of its physical and logical topologies. Initially, an assumption was that the number of communities within the infrastructure (physical) network layer were different from the one in the logical. They were detected using the Louvain method that performs graph partitioning on the hierarchical streets structure. Further, the number of communities in the relational network layer (i.e. accessibility to locations) was detected based on the OD accessibility matrix established from the functional dependency between the household locations and predefined points of interest. The communities from the graph of the ‘relational layer' were discovered with the single-link hierarchical clustering algorithm. The number of communities observed in the physical and the logical topologies of the eight shires significantly deviated

The perceptual qualities of concrete : a change in paradigm

La recherche porte sur la perception de qualité des artefacts en béton, et ce depuis la perspective disciplinaire du design industriel. Afin de documenter et examiner les applications et perceptions contemporaines de ce matériau, nous nous attardons à l’évolution des technologies du béton en termes de recettes, techniques de mise en forme, usages, ainsi que ses différentes appréciations. Une revue de littérature a permis de formuler la problématique et d’organiser les données recueillies afin de répondre à nos questions de recherche. Ainsi, nous avons identifié certains événements marquants ayant provoqué des développements importants dans l’évolution du béton. De plus, nous avons regroupé plusieurs témoignages illustrant différentes perceptions du matériau dans des contextes d’usages variés. Les résultats de la recherche ont été interprétés en mettant de l’avant une méthodologie qualitative de recherche. Nous avons également étudié une sélection d’artéfacts en béton à travers des observations empiriques non participatives ainsi que deux cas sélectionnés. Cependant, ce type de recherche à la première personne est influencé par l’auteure, ses expériences vécues, son bagage culturel ainsi que son regard disciplinaire. Ainsi, il était important de valider ces observations teintées par l’appréciation de l’auteure, et ce en triangulant les données avec celles regroupées de documents historiques, scientifiques, techniques et médiatiques. Plusieurs méthodes et outils analytiques ont été mobilisés afin d’organiser les résultats de la recherche. Des cartes chronologiques nous ont permis d’isoler et d’illustrer les étapes déterminantes ayant affecté l’histoire du béton (i.e. la découverte du ciment Portland, etc.). À des catégorisations, nous avons pu classer et comparer certaines données plus spécifiques aux recettes et applications du matériau (i.e. les bétons primitifs – modernes, les bétons structuraux – non-structuraux, etc.). Des cartographiques sémantiques nous ont permis d’interpréter les témoignages compilés des différentes perceptions du béton et ce en se basant sur une échelle sémantique bipolaire (i.e. le béton est laid – beau, le béton est froid – chaud, etc.). Enfin, nous nous sommes basés sur le cadre d’expériences de produits et matériaux (product and material experiences framework) proposé par Desmet et Hekkert (2007) afin d’interpréter les appréciations des artéfacts en béton recueillis à travers la revue de littérature ainsi que les observations empiriques à la première personne. La recherche montre que la perception de qualité du béton fait face à un dualisme qui oppose ses avantages techno-économiques avec son impact environnemental ainsi que la détérioration prématurée de sa surface. Malgré l’appréciation générale de sa versatilité, accessibilité et performance technique, une prise de conscience collective semble rendre les acteurs plus conscients de l’empreinte écologique résultant du cycle de vie du béton. De plus, la recherche démontre que les idéologies sont en train d’évoluer vers des pratiques et modes de vies plus durables malgré les habitudes de surconsommation de la société moderne. En mettant moins l’emphase sur la perfection superficielle, les designers sont de plus en plus motivés à trouver inspiration dans des pratiques plus sensibles et résilientes afin de trouver des solutions durables face aux enjeux urbains. Les dernières tendances révèlent l’émergence d’alternatives plus éco-responsables et innovantes comparées au béton traditionnel. Ainsi, nous trouvons des recettes de béton plus écologiques (i.e. substitution du ciment Portland avec des produits dérivés d’autres industries, etc.) ou des techniques de mise en forme plus optimisées afin de réduire les pertes en offrant un langage esthétique surprenant (i.e. impression 3D, etc.). Ces technologies donnent naissance à de nouvelles applications du béton dans différents domaines inattendus en dehors de l’architecture et de l’ingénierie (i.e. design de produits, art, cinématographie, etc.). La recherche met en lumière changement de paradigme quant à la perception de qualité du béton qui semble être entrainé par la migration des idéologies sociétales vers un modèle qui trouve de la valeur et de la beauté dans les imperfections. Ainsi, des acteurs semblent de plus en plus apprécier le béton avec ses imperfections naturelles, et ont tendance à plus vouloir préserver les artéfacts vieillissants.The research investigates the quality perceptions of concrete artifacts from an industrial design standpoint. In order to document and examine how the material is being used and perceived nowadays, the study looks into the evolution of concrete technologies including its recipes, manufacturing techniques, and uses, as well as its appraisals. A literature review helped us understand the problem field and organize the data amassed in order to find answers to our research questions. We were thus able to identify the critical milestones that triggered change throughout concrete’s historical evolution, as well as gather different testimonies of its perceptions within various contexts. Qualitative research methods were used to interpret our findings. We validated the data based on selected cases as well as non-participatory empirical observations of urban concrete artifacts from a first-person view. This method is influenced by the author’s lived experiences, cultural background, and disciplinary gaze. Therefore, it was necessary to complement the author’s interpretation by triangulating the data retrieved with information gathered from historical, scientific, technical, and mediatic literature. The results were organized and analyzed using various analytical tools and methods. Timeline mappings were used to isolate and illustrate critical milestones triggering change and important developments (e.g. the discovery of Portland Cement, etc.). Categorizations helped us clarify and compare the data gathered to provide a more specific overview of concrete recipes and uses (e.g. primitive – modern concretes, structural – non-structural recipes, etc.). Semantic mappings allowed us to interpret the complied testimonies on how concrete artifacts are perceived in addition to helping us isolate semantic qualities within a bipolar semantic space (e.g. concrete is ugly – beautiful, concrete is cold – warm, etc.). Lastly, a product and material experiences framework (Desmet & Hekkert, 2007) was used to interpret concrete artifacts’ appraisals as found within the testimonies retrieved, in addition to the first-person empirical observations. The research revealed that concrete’s quality perception is facing a dualism which draws attention to its ecological footprint as well as its surface’s premature deterioration with time. Although many seem to appreciate the material’s versatility, accessibility, and structural performance, the dualism can be partially attributed to the evolving collective consciousness which makes actors more aware of concrete’s environmental impacts across its lifecycle. The study thus showed that, despite modern society’s production and consumption habits which focus on the superficial perfection of the material world, ideologies are seen to be evolving and are increasingly interested in more sustainable practices and lifestyles. This can help motivate designers to seek inspiration from emotionally-durable and resilient principles, thus allowing them to better address urban challenges. The latest trends revealed new concrete mixes (e.g. substitution of Portland Cement with by-products of other industries, etc.) and manufacturing techniques (e.g. 3D-printing, etc.) which can offer eco-friendly and innovative alternatives to traditional concrete productions. These emerging solutions are seen to pave the way for unexpected applications in various fields (e.g., product design, art, cinematography, etc.), thus attracting other disciplines beyond engineering and architecture. The changing paradigm in the perception of concrete artifacts shows that value and beauty are not always associated with superficial perfection. In fact, more and more actors are found to reject premature obsolescence by embracing materials’ natural and imperfect behavior as they age with time

Facing Forward: Art & Theory from a Future Perspective

Contributors to this volume include participants in the Facing Forward Project of 2011-12, which started as a collaboration between the Stedelijk Museum Amsterdam, the Amsterdam School for Cultural Analysis at the University of Amsterdam, ..

Using MapReduce Streaming for Distributed Life Simulation on the Cloud

Distributed software simulations are indispensable in the study of large-scale life models but often require the use of technically complex lower-level distributed computing frameworks, such as MPI. We propose to overcome the complexity challenge by applying the emerging MapReduce (MR) model to distributed life simulations and by running such simulations on the cloud. Technically, we design optimized MR streaming algorithms for discrete and continuous versions of Conway’s life according to a general MR streaming pattern. We chose life because it is simple enough as a testbed for MR’s applicability to a-life simulations and general enough to make our results applicable to various lattice-based a-life models. We implement and empirically evaluate our algorithms’ performance on Amazon’s Elastic MR cloud. Our experiments demonstrate that a single MR optimization technique called strip partitioning can reduce the execution time of continuous life simulations by 64%. To the best of our knowledge, we are the first to propose and evaluate MR streaming algorithms for lattice-based simulations. Our algorithms can serve as prototypes in the development of novel MR simulation algorithms for large-scale lattice-based a-life models.https://digitalcommons.chapman.edu/scs_books/1014/thumbnail.jp

NEW METHODS FOR MINING SEQUENTIAL AND TIME SERIES DATA

Data mining is the process of extracting knowledge from large amounts of data. It covers a variety of techniques aimed at discovering diverse types of patterns on the basis of the requirements of the domain. These techniques include association rules mining, classification, cluster analysis and outlier detection. The availability of applications that produce massive amounts of spatial, spatio-temporal (ST) and time series data (TSD) is the rationale for developing specialized techniques to excavate such data. In spatial data mining, the spatial co-location rule problem is different from the association rule problem, since there is no natural notion of transactions in spatial datasets that are embedded in continuous geographic space. Therefore, we have proposed an efficient algorithm (GridClique) to mine interesting spatial co-location patterns (maximal cliques). These patterns are used as the raw transactions for an association rule mining technique to discover complex co-location rules. Our proposal includes certain types of complex relationships – especially negative relationships – in the patterns. The relationships can be obtained from only the maximal clique patterns, which have never been used until now. Our approach is applied on a well-known astronomy dataset obtained from the Sloan Digital Sky Survey (SDSS). ST data is continuously collected and made accessible in the public domain. We present an approach to mine and query large ST data with the aim of finding interesting patterns and understanding the underlying process of data generation. An important class of queries is based on the flock pattern. A flock is a large subset of objects moving along paths close to each other for a predefined time. One approach to processing a “flock query” is to map ST data into high-dimensional space and to reduce the query to a sequence of standard range queries that can be answered using a spatial indexing structure; however, the performance of spatial indexing structures rapidly deteriorates in high-dimensional space. This thesis sets out a preprocessing strategy that uses a random projection to reduce the dimensionality of the transformed space. We use probabilistic arguments to prove the accuracy of the projection and to present experimental results that show the possibility of managing the curse of dimensionality in a ST setting by combining random projections with traditional data structures. In time series data mining, we devised a new space-efficient algorithm (SparseDTW) to compute the dynamic time warping (DTW) distance between two time series, which always yields the optimal result. This is in contrast to other approaches which typically sacrifice optimality to attain space efficiency. The main idea behind our approach is to dynamically exploit the existence of similarity and/or correlation between the time series: the more the similarity between the time series, the less space required to compute the DTW between them. Other techniques for speeding up DTW, impose a priori constraints and do not exploit similarity characteristics that may be present in the data. Our experiments demonstrate that SparseDTW outperforms these approaches. We discover an interesting pattern by applying SparseDTW algorithm: “pairs trading” in a large stock-market dataset, of the index daily prices from the Australian stock exchange (ASX) from 1980 to 2002

A complex systems approach to education in Switzerland

The insights gained from the study of complex systems in biological, social, and engineered systems enables us not only to observe and understand, but also to actively design systems which will be capable of successfully coping with complex and dynamically changing situations. The methods and mindset required for this approach have been applied to educational systems with their diverse levels of scale and complexity. Based on the general case made by Yaneer Bar-Yam, this paper applies the complex systems approach to the educational system in Switzerland. It confirms that the complex systems approach is valid. Indeed, many recommendations made for the general case have already been implemented in the Swiss education system. To address existing problems and difficulties, further steps are recommended. This paper contributes to the further establishment complex systems approach by shedding light on an area which concerns us all, which is a frequent topic of discussion and dispute among politicians and the public, where billions of dollars have been spent without achieving the desired results, and where it is difficult to directly derive consequences from actions taken. The analysis of the education system's different levels, their complexity and scale will clarify how such a dynamic system should be approached, and how it can be guided towards the desired performance