Academic literature on the topic 'Computational science'

Cognitive research can contribute to the formal epistemological study of knowledge representation inasmuch as, firstly, it may be regarded as a descriptive science of the very same subject as that, of which formal epistemology is a normative one. And, secondly, the notion of representation plays a constitutive role in both disciplines, though differing therein in shades of its meaning. Representation, in my view, makes sense only being paired with computation. A process may be viewed as computational if it adheres to some algorithm and is substrate-independent. Traditionally, psychology is not directly determined by neuroscience, sticking to functional or dynamical analyses in the what-level and skipping mechanistic explanations in the how-level. Therefore, any version of computational approach in psychology is a very promising move in connecting the two scientific realms. On the other hand, the digital and linear computational approach of the classical cognitive science is of little help in this way, as it is not biologically realistic. Thus, what is needed there on the methodological level, is a shift from classical Turing-style computationalism to a generic computational theory that would comprehend the complicated architecture of neuronal computations. To this end, the cutting-edge cognitive neuroscience is in need of а satisfactory mathematical theory applicable to natural, particularly neuronal, computations. Computational systems may be construed as natural or artificial devices that use some physical processes on their lower levels as atomic operations for algorithmic processes on their higher levels. A cognitive system is a multi-level mechanism, in which linguistic, visual and other processors are built on numerous levels of more elementary operations, which ultimately boil down to atomic neural spikes. The hypothesis defended in this paper is that knowledge derives not only from an individual computational device, such as a brain, but also from the social communication system that, in its turn, may be presented as a kind of supercomputer of the parallel network architecture. Therefore, a plausible account of knowledge production and exchange must base on some mathematical theory of social computations, along with that of natural, particularly neuronal, ones.

Within a round table at the Institute of Philosophy of the Russian Academy of Sciences in the framework of the seminar ‘Interdisciplinary problems of cognitive sciences’ on December 19, 2019, a discussion was held on the possibility of identifying computational processes in nature, which identification, if successful, could constitute the ontological and methodological basis of cognitive (neuro) sciences. Some participants in the discussion expressed doubts about relevance of such an approach, putting forward the following arguments: computational processes deal with symbols by perforce and form part of human purposeful activity. In this article, I analyze these arguments and show that both symbolism and purposefulness, as the alleged attributes of computations, are inherent in human interpretations of the corresponding processes rather than in the course of their implementation. Here I also consider the ontological and methodological features of the computational approach to scientific knowledge and show how, owing to these features, this approach can help overcome the limitations of the traditional nomological model of science in the study of complex self-organizing systems.

Social and cognitive sciences have always faced the choice: either to meet the methodologi- cal standards given by successful natural sciences or to rely on their own. Talking about the conversion of knowledge into technology, the second way did not bring great success. The first way implies two alternative opportunities: reductionism or discovery of proprietary general laws. None of these chances have been realized with any satisfactory results, too. Methodological analysis shows that, to achieve significant progress in social sciences, what is missed there is not new facts or definitions but new conceptual schemes. The reason, as the author supposes, is the nomothetic approach being applied to systems with high degree of complexity and hierarchy. If we assume that social structures and processes are built upon cognitive psychological structures and processes, the former inherit the distributed computational architecture of the latter. The paper analyzes various conceptions of computations in order to determine their relevance to the task of building computational social science. The author offers a “generic” definition of computations as a process carried out by a computational system if the latter is understood as a mechanism of some representation. According to the author, the computationalization of social science implies “naturalization” of computations. This requires a theory that would explain the mechanism of growing complexity and hierarchy of natural (in particular, social) computational systems. As a method for constructing such a science, a kind of reverse engineering is proposed, which is recreation of a computational algorithmic scheme of social tissue by the determination and recombination of “social primitives” – elementary operations of social interaction.

The digitisation of archival materials and ingest of digitally born materials in digital archives has led to the possibilities of application of the big data analytical principles in the digital archives. The author explains the 5V characteristics of big data. He proceeds to define the concept of Computational Archival Science (CAS). Two CAS examples are given in order to illustrate the type of research that can be conducted in that area. Further, the author explains the prerequisites for engaging with CAS. Finally, suggestions on how archival institutions might get involved in CAS activities are given.

2015 - 2016
Computational science also know as scientific computing is a rapidly growing novel field that uses advanced computing in order to solve complex problems. This new discipline combines technologies, modern computational methods and simulations to address problems too complex to be reliably predicted only by theory and too dangerous or expensive to be reproduced in laboratories. Successes in computational science over the past twenty years have caused demand of supercomputing, to improve the performance of the solutions and to allow the growth of the models, in terms of sizes and quality. From a computer scientist’s perspective, it is natural to think to distribute the computation required to study a complex systems among multiple machines: it is well known that the speed of singleprocessor computers is reaching some physical limits. For these reasons, parallel and distributed computing has become the dominant paradigm for computational scientists who need the latest development on computing resources in order to solve their problems and the “Scalability” has been recognized as the central challenge in this science. In this dissertation the design and implementation of Frameworks, Parallel Languages and Architectures, which enable to improve the state of the art on Scalable Computational Science, are discussed. Frameworks. The proposal of D-MASON, a distributed version of MASON, a wellknown and popular Java toolkit for writing and running Agent-Based Simulations (ABSs). D-MASON introduces a framework level parallelization so that scientists that use the framework (e.g., a domain expert with limited knowledge of distributed programming) could be only minimally aware of such distribution. D-MASON, was began to be developed since 2011, the main purpose of the project was overcoming the limits of the sequentially computation of MASON, using distributed computing. D-MASON enables to do more than MASONin terms of size of simulations (number of agents and complexity of agents behaviors), but allows also to reduce the simulation time of simulations written in MASON. For this reason, one of the most important feature of D-MASON is that it requires a limited number of changing on the MASON’s code in order to execute simulations on distributed systems. v D-MASON, based on Master-Worker paradigm, was initially designed for heterogeneous computing in order to exploit the unused computational resources in labs, but it also provides functionality to be executed in homogeneous systems (as HPC systems) as well as cloud infrastructures. The architecture of D-MASON is presented in the following three papers, which describes all D-MASON layers: • Cordasco G., Spagnuolo C. and Scarano V. Toward the new version of D-MASON: Efficiency, Effectiveness and Correctness in Parallel and Distributed Agent-based Simulations. 1st IEEE Workshop on Parallel and Distributed Processing for Computational Social Systems. IEEE International Parallel & Distributed Processing Symposium 2016. • Cordasco G., De Chiara R., Mancuso A., Mazzeo D., Scarano V. and Spagnuolo C. Bringing together efficiency and effectiveness in distributed simulations: the experience with D-MASON. SIMULATION: Transactions of The Society for Modeling and Simulation International, June 11, 2013. • Cordasco G., De Chiara R., Mancuso A., Mazzeo D., Scarano V. and Spagnuolo C. A Framework for distributing Agent-based simulations. Ninth International Workshop Algorithms, Models and Tools for Parallel Computing on Heterogeneous Platforms of Euro-Par 2011 conference. Much effort has been made, on the Communication Layer, to improve the communication efficiency in the case of homogeneous systems. D-MASON is based on Publish/Subscribe (PS) communication paradigm and uses a centralized message broker (based on the Java Message Service standard) to deal with heterogeneous systems. The communication for homogeneous system uses the Message Passing Interface (MPI) standard and is also based on PS. In order to use MPI within Java, D-MASON uses a Java binding of MPI. Unfortunately, this binding is relatively new and does not provides all MPI functionalities. Several communication strategies were designed, implemented and evaluated. These strategies were presented in two papers: • Cordasco G., Milone F., Spagnuolo C. and Vicidomini L. Exploiting D-MASON on Parallel Platforms: A Novel Communication Strategy 2st Workshop on Parallel and Distributed Agent-Based Simulations of EuroPar 2014 conference. • Cordasco G., Mancuso A., Milone F. and Spagnuolo C. Communication strategies in Distributed Agent-Based Simulations: the experience with D-MASON 1st Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2013 conference. vi D-MASON provides also mechanisms for the visualization and gathering of the data in distributed simulation (available on the Visualization Layer). These solutions are presented in the paper: • Cordasco G., De Chiara R., Raia F., Scarano V., Spagnuolo C. and Vicidomini L. Designing Computational Steering Facilities for Distributed Agent Based Simulations. Proceedings of the ACM SIGSIM Conference on Principles of Advanced Discrete Simulation 2013. In DABS one of the most complex problem is the partitioning and balancing of the computation. D-MASON provides, in the Distributed Simulation layer, mechanisms for partitioning and dynamically balancing the computation. D-MASON uses field partitioning mechanism to divide the computation among the distributed system. The field partitioning mechanism provides a nice trade-off between balancing and communication effort. Nevertheless a lot of ABS are not based on 2D- or 3D-fields and are based on a communication graph that models the relationship among the agents. Inthiscasethefieldpartitioningmechanismdoesnotensuregoodsimulation performance. Therefore D-MASON provides also a specific mechanisms to manage simulation that uses a graph to describe agent interactions. These solutions were presented in the following publication: • Antelmi A., Cordasco G., Spagnuolo C. and Vicidomini L.. On Evaluating Graph Partitioning Algorithms for Distributed Agent Based Models on Networks. 3rd Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2015 conference. The field partitioning mechanism, intuitively, enables the mono and bi-dimensional partitioning of an Euclidean space. This approach is also know as uniform partitioning. But in some cases, e.g. simulations that simulate urban areas using a Geographical Information System (GIS), the uniform partitioning degrades the simulation performance, due to the unbalanced distribution of the agents on the field and consequently on the computational resources. In such a case, D-MASON provides a non-uniform partitioning mechanism (inspired by Quad-Tree data structure), presented in the following paper: • Lettieri N., Spagnuolo C. and Vicidomini L.. Distributed Agent-based Simulation and GIS: An Experiment With the dynamics of Social Norms. 3rd Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2015 conference. • G. Cordasco and C. Spagnuolo and V. Scarano. Work Partitioning on Parallel and Distributed Agent-Based Simulation. IEEE Workshop on vii Parallel and Distributed Processing for Computational Social Systems of International Parallel & Distributed Processing Symposium, 2017. The latest version of D-MASON provides a web-based System Management, to better use D-MASON in Cloud infrastructures. D-MASON on the Amazon EC2 Cloud infrastructure and its performance in terms of speed and cost were compared against D-MASON on an HPC environment. The obtained results, and the new System Management Layer are presented in the following paper: • MCarillo,GCordasco,FSerrapica,CSpagnuolo,P.Szufel,andL.Vicidomini. D-Mason on the Cloud: an Experience with Amazon Web Services. 4rd Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2016 conference. ParallelLanguages. The proposal of an architecture, which enable to invoke code supported by a Java Virtual Machine (JVM) from code written in C language. Swft/T, is a parallel scripting language for programming highly concurrent applications in parallel and distributed environments. Swift/T is the reimplemented version of Swift language, with a new compiler and runtime. Swift/T improve Swift, allowing scalability over 500 tasks per second, load balancing feature, distributed data structures, and dataflow-driven concurrent task execution. Swif/T provides an interesting feature the one of calling easily and natively other languages (as Python, R, Julia, C) by using special language functions named leaf functions. Considering the actual trend of some supercomputing vendors (such as Cray Inc.) that support in its processors Java Virtual Machines (JVM), it is desirable to provide methods to call also Java code from Swift/T. In particular is really attractive to be able to call scripting languages for JVM as Clojure, Scala, Groovy, JavaScript etc. For this purpose a C binding to instanziate and call JVM was designed. This binding is used in Swif/T (since the version 1.0) to develop leaf functions that call Java code. The code are public available at GitHub project page. Frameworks. The proposal of two tools, which exploit the computing power of parallel systems to improve the effectiveness and the efficiency of Simulation Optimization strategies. Simulations Optimization (SO) is used to refer to the techniques studied for ascertaining the parameters of a complex model that minimize (or maximize) given criteria (one or many), which can only be computed by performing a simulation run. Due to the the high dimensionality of the search space, the heterogeneity of parameters, the irregular shape and the stochastic nature of the objective evaluation function, the tuning of such systems is extremely demanding from the computational point of view. The first frameworks is SOF: Zero Configuration Simulation Optimization Framework on the Cloud, it was designed to run SO process in viii the cloud. SOF is based on the Apache Hadoop infrastructure and is presented in the following paper: • Carillo M., Cordasco G., Scarano V., Serrapica F., Spagnuolo C. and Szufel P. SOF: Zero Configuration Simulation Optimization Framework on the Cloud. Parallel, Distributed, and Network-Based Processing 2016. The second framework is EMEWS: Extreme-scale Model Exploration with Swift/T, it has been designed at Argonne National Laboratory (USA). EMEWS as SOF allows to perform SO processes in distributed system. Both the frameworks are mainly designed for ABS. In particular EMEWS was tested using the ABS simulation toolkit Repast. Initially, EMEWS was not able to easily execute out of the box simulations written in MASON and NetLogo. This thesis presents new functionalities of EMEWS and solutions to easily execute MASON and NetLogo simulations on it. The EMEWS use cases are presented in the following paper: • J. Ozik, N. T. Collier, J. M. Wozniak and C. Spagnuolo From Desktop To Large-scale Model Exploration with Swift/T. Winter Simulation Conference 2016. Architectures. The proposal of an open-source, extensible, architecture for the visualization of data in HTML pages, exploiting a distributed web computing. Following the Edge-centric Computing paradigm, the data visualization is performed edge side ensuring data trustiness, privacy, scalability and dynamic data loading. The architecture has been exploited in the Social Platform for Open Data (SPOD). The proposed architecture, that has also appeared in the following papers: • G. Cordasco, D. Malandrino, P. Palmieri, A. Petta, D. Pirozzi, V. Scarano, L. Serra, C. Spagnuolo, L. Vicidomini A Scalable Data Web Visualization Architecture. Parallel, Distributed, and Network-Based Processing 2017. • G. Cordasco, D. Malandrino, P. Palmieri, A. Petta, D. Pirozzi, V. Scarano, L. Serra, C. Spagnuolo, L. Vicidomini An Architecture for Social Sharing and Collaboration around Open Data Visualisation. In Poster Proc. of the 19th ACM conference on "Computer-Supported Cooperative Work and Social Computing 2016. • G. Cordasco, D. Malandrino, P. Palmieri, A. Petta, D. Pirozzi, V. Scarano, L. Serra, C. Spagnuolo, L. Vicidomini An extensible architecture for an ecosystem of visualization web-components for Open Data Maximising interoperability Workshop— core vocabularies, location-aware data and more 2015. [edited by author]
Computational science anche conosciuta come calcolo scientifico è un settore in rapida crescita che usa il calcolo avanzato per affrontare problemi complessi. Questa nuova disciplina, combina tecnologia, moderni metodi computazionali e simulazioni per affrontare problemi troppo difficili da poter essere studiati solo in teoria o troppo pericolosi e costosi per poter essere riprodotti sperimentalmente in laboratorio. I progressi dell’ultimo ventennio in computational science hanno sfruttato il supercalcolo per migliorare le performance delle soluzioni e permettere la crescita dei modelli, in termini di dimensioni e qualità dei risultati ottenuti. Le soluzioni adottate si avvalgono del calcolo distribuito: è ben noto che la velocità di un computer con un singolo processore sta raggiungendo dei limiti fisici. Per queste ragioni, la computazione parallela e distribuita è diventata il principale paradigma di calcolo per affrontare i problemi nell’ambito della computational science, in cui la scalabilità delle soluzioni costituisce la sfida da affrontare. In questa tesi vengono discusse la progettazione e l’implementazione di Framework, Linguaggi Paralleli e Architetture che consentono di migliorare lo stato dell’arte della Scalable Computational Science. In particolare, i maggiori contributi riguardano: Frameworks. La proposta di D-MASON, una versione distribuita di MASON, un toolkit Java per la scrittura e l’esecuzione di simulazioni basate su agenti (AgentBased Simulations, ABSs). D-MASON introduce la parallelizzazione a livello framework per far si che gli scienziati che lo utilizzano (ad esempio un esperto con limitata conoscenza della programmazione distribuita) possano rendersi conto solo minimamente di lavorare in ambiente distribuito (ad esempio esperti del dominio con limitata esperienza o nessuna esperienza nel calcolo distribuito). D-MASON è un progetto iniziato nel 2011, il cui principale obiettivo è quello di superare i limiti del calcolo sequenziale di MASON, sfruttando il calcolo distribuito. D-MASON permette di simulare modelli molto più complessi (in termini di numero di agenti e complessità dei comportamenti dei singoli agenti) rispetto a MASON e inoltre consente, a parità di calcolo, di ridurre il tempo necessario ad eseguire le simulazioni MASON. D-MASON è stato progettato in modo da permettere la migrazione di simulazioni scritte in MASON con un numero limitato di modifiche da apportare al codice, al fine di garantire il massimo della semplicità d’uso. v D-MASON è basato sul paradigma Master-Worker, inizialmente pensato per sistemi di calcolo eterogenei, nelle sue ultime versioni consente l’esecuzione anche in sistemi omogenei come sistemi HPC e infrastrutture di cloud computing. L’architettura di D-MASON è stata presentata nelle seguenti pubblicazioni: • Cordasco G., Spagnuolo C. and Scarano V. Toward the new version of D-MASON: Efficiency, Effectiveness and Correctness in Parallel and Distributed Agent-based Simulations. 1st IEEE Workshop on Parallel and Distributed Processing for Computational Social Systems. IEEE International Parallel & Distributed Processing Symposium 2016. • Cordasco G., De Chiara R., Mancuso A., Mazzeo D., Scarano V. and Spagnuolo C. Bringing together efficiency and effectiveness in distributed simulations: the experience with D-MASON. SIMULATION: Transactions of The Society for Modeling and Simulation International, June 11, 2013. • Cordasco G., De Chiara R., Mancuso A., Mazzeo D., Scarano V. and Spagnuolo C. A Framework for distributing Agent-based simulations. Ninth International Workshop Algorithms, Models and Tools for Parallel Computing on Heterogeneous Platforms of Euro-Par 2011 conference. Uno degli strati architetturali di D-MASON che ne determina le prestazioni, è il il Communication Layer, il quale offre le funzionalità di comunicazione tra tutte le entità coinvolte nel calcolo. La comunicazione in D-MASON è basata sul paradigma Publish/Subscribe (PS). Al fine di soddisfare la flessibilità e la scalabilità richiesta, vengono fornite due strategie di comunicazione, una centralizzata (utilizzando Java Message Service) e una decentralizzata (utilizzando Message Passing Interface). La comunicazione in sistemi omogenei è sempre basata su PS ma utilizza lo standard Message Passing Interface (MPI). Al fine di utilizzare MPI in Java, lo strato di comunicazione di D-MASON è implementato sfruttando un binding Java a MPI. Tale soluzione non permette però l’utilizzo di tutte le funzionalità di MPI. Al tal proposito molteplici soluzioni sono stare progettate e implementate, e sono presentate nelle seguenti pubblicazioni: • Cordasco G., Milone F., Spagnuolo C. and Vicidomini L. Exploiting D-MASON on Parallel Platforms: A Novel Communication Strategy 2st Workshop on Parallel and Distributed Agent-Based Simulations of EuroPar 2014 conference. • Cordasco G., Mancuso A., Milone F. and Spagnuolo C. Communication strategies in Distributed Agent-Based Simulations: the experience with D-MASON 1st Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2013 conference. vi D-MASON offre anche meccanismi per la visualizzazione centralizzata e la raccolta di informazioni in simulazioni distribuite (tramite il Visualization Layer). I risultati ottenuti sono stati presentati nella seguente pubblicazione: • Cordasco G., De Chiara R., Raia F., Scarano V., Spagnuolo C. and Vicidomini L. Designing Computational Steering Facilities for Distributed Agent Based Simulations. Proceedings of the ACM SIGSIM Conference on Principles of Advanced Discrete Simulation 2013. Quando si parla di simulazioni distribuite una delle principali problematiche è il bilanciamento del carico. D-MASON offre, nel Distributed Simulation Layer, meccanismi per il partizionamento dinamico e il bilanciamento del carico. DMASON utilizza la tecnica del field partitioning per suddividere il lavoro tra le entità del sistema distribuito. La tecnica di field partitioning consente di ottenere un buon equilibrio tra il bilanciamento del carico e l’overhead di comunicazione. Molti modelli di simulazione non sono basati su spazi 2/3-dimensionali ma bensì modellano le relazioni tra gli agenti utilizzando strutture dati grafo. In questi casi la tecnica di field partitioning non garantisce soluzioni che consentono di ottenere buone prestazioni. Per risolvere tale problema, D-MASON fornisce particolari soluzioni per simulazioni che utilizzano i grafi per modellare le relazioni tra gli agenti. I risultati conseguiti sono stati presentati nella seguente pubblicazione: • Antelmi A., Cordasco G., Spagnuolo C. and Vicidomini L.. On Evaluating Graph Partitioning Algorithms for Distributed Agent Based Models on Networks. 3rd Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2015 conference. Il metodo di field partitioning consente il partizionamento di campi Euclidei mono e bi-dimensionali; tale approccio è anche conosciuto con il nome di partizionamento uniforme. In alcuni casi, come ad esempio simulazioni che utilizzano Geographical Information System (GIS), il metodo di partizionamento uniforme non è in grado di garantire buone prestazioni, a causa del posizionamento non bilanciato degli agenti sul campo di simulazione. In questi casi, D-MASON offre un meccanismo di partizionamento non uniforme (inspirato alla struttura dati Quad-Tree), presentato nelle seguenti pubblicazioni: • Lettieri N., Spagnuolo C. and Vicidomini L.. Distributed Agent-based Simulation and GIS: An Experiment With the dynamics of Social Norms. 3rd Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2015 conference. • G. Cordasco and C. Spagnuolo and V. Scarano. Work Partitioning on Parallel and Distributed Agent-Based Simulation. IEEE Workshop on vii Parallel and Distributed Processing for Computational Social Systems of International Parallel & Distributed Processing Symposium, 2017. Inoltre, D-MASON èstatoestesoalloscopodifornireun’infrastrutturaSimulation-asa-Service(SIMaaS),chesemplificailprocessodiesecuzionedisimulazionidistribuite in un ambiente di Cloud Computing. D-MASON nella sua versione più recente offre uno strato software di management basato su web, che ne consente estrema facilità d’uso in ambienti Cloud. Utilizzando il System Management, D-MASON è stato sperimentato sull’infrastruttura Cloud Amazon EC2 confrontando le prestazioni in questo ambiente cloud con un sistema HPC. I risultati ottenuti sono stati presentati nella seguente pubblicazione: • MCarillo,GCordasco,FSerrapica,CSpagnuolo,P.Szufel,andL.Vicidomini. D-Mason on the Cloud: an Experience with Amazon Web Services. 4rd Workshop on Parallel and Distributed Agent-Based Simulations of Euro-Par 2016 conference. LinguaggiParalleli. La proposta di un’architettura, la quale consente di invocare il codice per Java Virtual Machine (JVM) da codice scritto in linguaggio C. Swift/T è un linguaggio di scripting parallelo per sviluppare applicazioni altamente scalabili in ambienti paralleli e distribuiti. Swift/T è l’implementazione del linguaggio Swift per ambienti HPC. Swift/T migliora il linguaggio Swift, consentendo la scalabilità fino a 500 task per secondo, il bilanciamento del carico, strutture dati distribuite, e dataflow task execution. Swift/T consente di invocare nativamente codice scritto in altri linguaggi (come Python, R, Julia e C) utilizzando particolari funzioni definite come leaf function. Il trend attuale di molti produttori di sistemi di supercalcolo (come Cray Inc.), è quello di offrire processori che supportano JVM. Considerato ciò in questa tesi viene presentato il metodo adottato in Swift/T per l’invocazione di linguaggi per JVM (come Java, Clojure, Scala, Groovy, JavaScript) da Swift/T. A tale scopo è stato realizzato un binding C per l’invocazione e la gestione di codice per JVM. Questa soluzione è stata utilizzata in Swift/T (dalla versione 1.0) per estendere il supporto del linguaggio anche a linguaggi per JVM. Il codice sviluppato è stato rilasciato sotto licenza open source ed è disponibile in un repository pubblico su GitHub. Frameworks. La proposta di due tool che sfruttano la potenza di calcolo di sistemi distribuiti per migliorare l’efficacia e l’efficienza di strategie di Simulation Optimization. Simulation Optimization (SO) si riferisce alle tecniche utilizzate per l’individuazione dei parametri di un modello complesso che minimizzano (o massimizzano) determinati criteri, i quali possono essere computati solo tramite l’esecuzione di una simulazione. A causa dell’elevata dimensionalità dello spazio dei parametri, della loro eterogeneità e, della natura stocastica della funzione di viii valutazione, la configurazione di tali sistemi è estremamente onerosa dal punto di vista computazionale. In questo lavoro sono presentati due framework per SO. Il primo framework è SOF:Zero ConfigurationSimulation OptimizationFramework on the Cloud, progettato per l’esecuzione del processo SO in ambienti di cloud computing. SOF è basato su Apache Hadoop ed è presentato nella seguente pubblicazione: • Carillo M., Cordasco G., Scarano V., Serrapica F., Spagnuolo C. and Szufel P. SOF: Zero Configuration Simulation Optimization Framework on the Cloud. Parallel, Distributed, and Network-Based Processing 2016. Il secondo framework è EMEWS: Extreme-scale Model Exploration with Swift/T, progettato per eseguire processi SO in sistemi HPC. Entrambi i framework sono stati sviluppati principalmente per ABS. In particolare EMEWS è stato sperimentato utilizzando il toolkit ABS chiamato Repast. Nella sua prima versione EMEWS non supportava simulazioni scritte in MASON e NetLogo. In questo lavoro di tesi sono descritte alcune funzionalità di EMEWS che consentono il supporto a tali simulazioni. EMEWS e alcuni casi d’uso sono presentati nella seguente pubblicazione: • J. Ozik, N. T. Collier, J. M. Wozniak and C. Spagnuolo From Desktop To Large-scale Model Exploration with Swift/T. Winter Simulation Conference 2016. Architetture. La proposta di un’architettura open source per la visualizzazione web di dati dinamici. Tale architettura si basa sul paradigma di Edge-centric Computing; la visualizzazione dei dati è eseguita lato client, garantendo in questo modo l’affidabilità dei dati, la privacy e la scalabilità in termini di numero di visualizzazioni concorrenti. L’architettura è stata utilizzata all’interno della piattaforma sociale SPOD (Social Platform for Open Data), ed è stata presentata nelle seguenti pubblicazioni: • G. Cordasco, D. Malandrino, P. Palmieri, A. Petta, D. Pirozzi, V. Scarano, L. Serra, C. Spagnuolo, L. Vicidomini A Scalable Data Web Visualization Architecture. Parallel, Distributed, and Network-Based Processing 2017. • G. Cordasco, D. Malandrino, P. Palmieri, A. Petta, D. Pirozzi, V. Scarano, L. Serra, C. Spagnuolo, L. Vicidomini An Architecture for Social Sharing and Collaboration around Open Data Visualisation. In Poster Proc. of the 19th ACM conference on "Computer-Supported Cooperative Work and Social Computing 2016. • G. Cordasco, D. Malandrino, P. Palmieri, A. Petta, D. Pirozzi, V. Scarano, L. Serra, C. Spagnuolo, L. Vicidomini An extensible architecture for an ecosystem of visualization web-components for Open Data Maximising interoperability Workshop— core vocabularies, location-aware data and more 2015. [a cura dell'autore]
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A presente tese é formada por três trabalhos científicos na área de Management Science Computacional. A gestão moderna e a alta tecnologia interagem em múltiplas e profundas formas. O professor Andre Ng diz aos seus estudantes na Escola de Negócios de Stanford que “Inteligência Artificial é a nova eletricidade”, como sua forma hiperbólica de enfatizar o potencial transformador da tecnologia. O primeiro trabalho é inspirado na possibilidade de que haverá alguma forma de dinheiro digital e estuda ledger distribuídas, propondo e analisando o Hathor, uma arquitetura alternativa para criptomoedas escaláveis. O segundo trabalho pode ser um item crucial no entendimento de tomadas de decisão, nos trazendo um modelo formal de recognition-primed decisions. Situada na intersecção entre psicologia cognitiva, ciência da computação, neuro-ciência e inteligência artifical, ele apresenta um framework open-source, multi-plataforma e altamente paralelo da Sparse Distributed Memory e analisa a dinâmica da memória e algumas aplicações. O terceiro e último trabalho se situa na intersecção entre marketing, difusão de inovação tecnologica e modelagem, extendendo o famoso modelo de Bass para levar em consideração usuário que, após adotar a tecnologia por um tempo, decidiram rejeitá-la.
This thesis presents three specific, self-contained, scientific papers in the Computational Management Science area. Modern management and high technology interact in multiple, profound, ways. Professor Andrew Ng tells students at Stanford’s Graduate School of Business that “AI is the new electricity”, as his hyperbolic way to emphasize the potential transformational power of the technology. The first paper is inspired by the possibility that there will be some form of purely digital money and studies distributed ledgers, proposing and analyzing Hathor, an alternative architecture towards a scalable cryptocurrency. The second paper may be a crucial item in understanding human decision making, perhaps, bringing us a formal model of recognition-primed decision. Lying at the intersection of cognitive psychology, computer science, neuroscience, and artificial intelligence, it presents an open-source, cross-platform, and highly parallel framework of the Sparse Distributed Memory and analyzes the dynamics of the memory with some applications. Last but not least, the third paper lies at the intersection of marketing, diffusion of technological innovation, and modeling, extending the famous Bass model to account for users who, after adopting the innovation for a while, decide to reject it later on.

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This work is composed of two contributions. One borrows from the work of Charles Kemp and Joshua Tenenbaum, concerning the discovery of structural form: their model is used to study the Business Week Rankings of U.S. Business Schools, and to investigate how other structural forms (structured visualizations) of the same information used to generate the rankings can bring insights into the space of business schools in the U.S., and into rankings in general. The other essay is purely theoretical in nature. It is a study to develop a model of human memory that does not exceed our (human) psychological short-term memory limitations. This study is based on Pentti Kanerva’s Sparse Distributed Memory, in which human memories are registered into a vast (but virtual) memory space, and this registration occurs in massively parallel and distributed fashion, in ideal neurons.
Este trabalho é composto de duas contribuições. Uma se usa do trabalhode Charles Kemp e Joshua Tenenbaum sobre a descoberta da forma estrutural: o seu modelo é usado para estudar os rankings da revista Business Week sobre escolas de administração, e para investigar como outras formas estruturais (visualizações estruturadas) da mesma informação usada para gerar os rankings pode trazer discernimento no espaço de escolas de negócios nos Estados Unidos e em rankings em geral. O outro ensaio é de natureza puramente teórica. Ele é um estudo no desenvolvimento de um modelo de memória que não excede os nossos (humanos) limites de memória de curto-prazo. Este estudo se baseia na Sparse Distributed Memory (Memória Esparsa e Distribuida) de Pentti Kanerva, na qual memórias humanas são registradas em um vasto (mas virtual) espaço, e este registro ocorre de forma maciçamente paralela e distribuida, em neurons ideais.

The thesis is a collection of six stand-alone chapters aimed at setting the foundations for the philosophy of computational social science. Agent-based modelling has been used for social research since the nineties. While at the beginning it was simply conceived as a methodological alternative, recently, the notion of ‘computational social science’ has started to be used to denote a separate disciplinary field. There are important differences with mainstream social science and traditional social research. Yet, the literature in the field has not accounted for these differences. Computational social science is a strongly practice-oriented field, where theoretical and philosophical concerns have been pushed into the background. This thesis presents an initial analysis of the methodology, epistemology and ontology of computational social science, by examining the following topics: 1) verification and validation and 2) modelling and theorising, 3) mechanisms 4) explanation 5) agency, action and interaction and 6) entities and process philosophy. Five general conclusions are drawn from the thesis. It is first argued that the wider ontological base in agent-based modelling allows for a new approach to traditional social dualisms, moving away from the methodological individualism that dominates computational social science. Second, the need to place a distinction between explanation and understanding and to make explanatory goals explicit is highlighted. Third, it is claimed that computational social science needs to pay attention to the social epistemology of the field, for this could provide important insights regarding values, ideologies and interests that underlie the practice of agent-based modelling. Fourth, it is suggested that a more robust theorisation regarding the experimental and model-based character of agent-based modelling should be developed. Finally, it is argued that the method can greatly contribute to the development of a processual account of social life.

This Thesis describes our work at the boundary between Computer Science and Cognitive (Neuro)Science. In particular, (1) we have worked on methodological improvements to clustering-based meta-analysis of neuroimaging data, which is a technique that allows to collectively assess, in a quantitative way, activation peaks from several functional imaging studies, in order to extract the most robust results in the cognitive domain of interest. Hierarchical clustering is often used in this context, yet it is prone to the problem of non-uniqueness of the solution: a different permutation of the same input data might result in a different clustering result. In this Thesis, we propose a new version of hierarchical clustering that solves this problem. We also show the results of a meta-analysis, carried out using this algorithm, aimed at identifying specific cerebral circuits involved in single word reading. Moreover, (2) we describe preliminary work on a new connectionist model of single word reading, named the two-component model because it postulates a cascaded information flow from a more cognitive component that computes a distributed internal representation for the input word, to an articulatory component that translates this code into the corresponding sequence of phonemes. Output production is started when the internal code, which evolves in time, reaches a sufficient degree of clarity; this mechanism has been advanced as a possible explanation for behavioral effects consistently reported in the literature on reading, with a specific focus on the so called serial effects. This model is here discussed in its strength and weaknesses. Finally, (3) we have turned to consider how features that are typical of human cognition can inform the design of improved artificial agents; here, we have focused on modelling concepts inspired by emotion theory. A model of emotional interaction between artificial agents, based on probabilistic finite state automata, is presented: in this model, agents have personalities and attitudes that can change through the course of interaction (e.g. by reinforcement learning) to achieve autonomous adaptation to the interaction partner. Markov chain properties are then applied to derive reliable predictions of the outcome of an interaction. Taken together, these works show how the interplay between Cognitive Science and Computer Science can be fruitful, both for advancing our knowledge of the human brain and for designing more and more intelligent artificial systems.

Visibilitzant la vida quotidiana de la gent, Twitter s'ha convertit en una de les plataformes d'intercanvi d'informació més importants i ha atret ràpidament l'atenció dels científics. Investigadors de tot el món s'han centrat en les ciències socials i en els estudis d'Internet amb dades de Twitter com a mostra del món real, i en l'última dècada s'han dissenyat nombroses eines d'anàlisis i algorismes. La present tesi doctoral consta de tres recerques, en primer lloc, donats els 14 anys (fins a 2020) d'història des de la fundació de Twitter, hem assistit a una explosió de publicacions científiques relacionades, però el panorama actual de la recerca en aquesta plataforma de mitjans socials continuava sent desconegut. Per a omplir aquest buit de recerca, vam fer una anàlisi bibliomètrica dels estudis relacionats amb Twitter per a analitzar com van evolucionar els estudis de Twitter al llarg del temps, i per a proporcionar una descripció general de l'entorn acadèmic de recerca de Twitter des d'un nivell macro. En segon lloc, atès que hi ha moltes eines de programari analític que estan disponibles actualment per a la recerca en Twitter, una pregunta pràctica per als investigadors júnior és com triar el programari més apropiat per al seu propi projecte de recerca. Per a resoldre aquest problema, vam fer una revisió del programari per a alguns dels sistemes integrats que es consideren més rellevants per a la recerca en ciències socials. Atès que els investigadors júnior en ciències socials poden enfrontar-se a possibles limitacions financeres, vam reduir el nostre abast per a centrar-nos únicament en el programari gratuït i de baix cost. En tercer lloc, donada l'actual crisi de salut pública, hem observat que els mitjans de comunicació social són una de les fonts d'informació i notícies més accessibles per al públic. Durant una pandèmia, la forma en què s'emmarquen els problemes de salut i les malalties en la premsa influeix en la comprensió del públic sobre l'actual brot epidèmic i les seves actituds i comportaments. Per tant, decidim usar Twitter com una font de notícies de fàcil accés per a analitzar l'evolució dels marcs de notícies espanyols durant la pandèmia COVID-19. En general, les tres recerques s'han associat estretament amb l'aplicació de mètodes computacionals, incloent la recol·lecció de dades en línia, la mineria de textos, l'anàlisi de xarxes i la visualització de dades. Aquest projecte de doctorat ha mostrat com la gent estudia i utilitza Twitter des de tres nivells diferents: el nivell acadèmic, el nivell pràctic i el nivell empíric.
Visibilizando la vida cotidiana de la gente, Twitter se ha convertido en una de las plataformas de intercambio de información más importantes y ha atraído rápidamente la atención de los científicos. Investigadores de todo el mundo se han centrado en las ciencias sociales y en los estudios de Internet con datos de Twitter como muestra del mundo real, y en la última década se han diseñado numerosas herramientas de análisis y algoritmos. La presente tesis doctoral consta de tres investigaciones, en primer lugar, dados los 14 años (hasta 2020) de historia desde la fundación de Twitter, hemos asistido a una explosión de publicaciones científicas relacionadas, pero el panorama actual de la investigación en esta plataforma de medios sociales seguía siendo desconocido. Para llenar este vacío de investigación, hicimos un análisis bibliométrico de los estudios relacionados con Twitter para analizar cómo evolucionaron los estudios de Twitter a lo largo del tiempo, y para proporcionar una descripción general del entorno académico de investigación de Twitter desde un nivel macro. En segundo lugar, dado que hay muchas herramientas de software analítico que están disponibles actualmente para la investigación en Twitter, una pregunta práctica para los investigadores junior es cómo elegir el software más apropiado para su propio proyecto de investigación. Para resolver este problema, hicimos una revisión del software para algunos de los sistemas integrados que se consideran más relevantes para la investigación en ciencias sociales. Dado que los investigadores junior en ciencias sociales pueden enfrentarse a posibles limitaciones financieras, redujimos nuestro alcance para centrarnos únicamente en el software gratuito y de bajo coste. En tercer lugar, dada la actual crisis de salud pública, hemos observado que los medios de comunicación social son una de las fuentes de información y noticias más accesibles para el público. Durante una pandemia, la forma en que se enmarcan los problemas de salud y las enfermedades en la prensa influye en la comprensión del público sobre el actual brote epidémico y sus actitudes y comportamientos. Por lo tanto, decidimos usar Twitter como una fuente de noticias de fácil acceso para analizar la evolución de los marcos de noticias españoles durante la pandemia COVID-19. En general, las tres investigaciones se han asociado estrechamente con la aplicación de métodos computacionales, incluyendo la recolección de datos en línea, la minería de textos, el análisis de redes y la visualización de datos. Este proyecto de doctorado ha mostrado cómo la gente estudia y utiliza Twitter desde tres niveles diferentes: el nivel académico, el nivel práctico y el nivel empírico.
As Twitter has covered up people’s daily life, it has became one of the most important information exchange platforms, and quickly attracted scientists’ attention. Researchers around the world have highly focused on social science and internet studies with Twitter data as a real world sample, and numerous analytics tools and algorithms have been designed in the last decade. The present doctoral thesis consists of three researches, first, given the 14 years (until 2020) of history since the foundation of Twitter, an explosion of related scientific publications have been witnessed, but the current research landscape on this social media platform remained unknown, to fill this research gap, we did a bibliometric analysis on Twitter-related studies to analyze how the Twitter studies evolved over time, and to provide a general description of the Twitter research academic environment from a macro level. Second, since there are many analytic software tools that are currently available for Twitter research, a practical question for junior researchers is how to choose the most appropriate software for their own research project, to solve this problem, we did a software review for some of the integrated frameworks that are considered most relevant for social science research, given that junior social science researchers may face possible financial constraints, we narrowed our scope to solely focus on the free and low-cost software. Third, given the current public health crisis, we have noticed that social media are one of the most accessed information and news sources for the public. During a pandemic, how health issues and diseases are framed in the news release impacts public’s understanding of the current epidemic outbreak and their attitudes and behaviors. Hence, we decided to use Twitter as an easy-access news source to analyze the evolution of the Spanish news frames during the COVID-19 pandemic. Overall, the three researches have closely associated with the application of computational methods, including online data collection, text mining, complex network and data visualization. And this doctoral project has discovered how people study and use Twitter from three different levels: the academic level, the practical level and the empirical level.

The present thesis is concerned to the application of first-principles self-consistent total-energy calculations within the density functional theory on different topics in materials science.

Crystallographic phase-transitions under high-pressure has been study for TiO2, FeI2, Fe3O4, Ti, the heavy alkali metals Cs and Rb, and C3N4. A new high-pressure polymorph of TiO2 has been discovered, this new polymorph has an orthorhombic OI (Pbca) crystal structure, which is predicted theoretically for the pressure range 50 to 100 GPa. Also, the crystal structures of Cs and Rb metals have been studied under high compressions. Our results confirm the recent high-pressure experimental observations of new complex crystal structures for the Cs-III and Rb-III phases. Thus, it is now certain that the famous isostructural phase transition in Cs is rather a new crystallographic phase transition.

The elastic properties of the new superconductor MgB2 and Al-doped MgB2 have been investigated. Values of all independent elastic constants (c11, c12, c13, c33, and c55) as well as bulk moduli in the a and c directions (Ba and Bc respectively) are predicted. Our analysis suggests that the high anisotropy of the calculated elastic moduli is a strong indication that MgB2 should be rather brittle. Al doping decreases the elastic anisotropy of MgB2 in the a and c directions, but, it will not change the brittle behaviour of the material considerably.

The three most relevant battery properties, namely average voltage, energy density and specific energy, as well as the electronic structure of the Li/LixMPO4 systems, where M is either Fe, Mn, or Co have been calculated. The mixing between Fe and Mn in these materials is also examined. Our calculated values for these properties are in good agreement with recent experimental values. Further insight is gained from the electronic density of states of these materials, through which conclusions about the physical properties of the various phases are made.

The electronic and magnetic properties of the dilute magnetic semiconductor Mn-doped ZnO has been calculated. We have found that for an Mn concentration of 5.6%, the ferromagnetic configuration is energetically stable in comparison to the antiferromgnetic one. A half-metallic electronic structure is calculated by the GGA approximation, where Mn ions are in a divalent state leading to a total magnetic moment of 5 μB per Mn atom.

Implicit Large Eddy Simulation (ILES) with high-resolution and high-order computational modelling has been applied to flows with turbulent mixing and combustion. Due to the turbulent nature, mixing of fuel and air and the subsequent combustion still remain challenging for computational fluid dynamics. However, recently ILES, an advanced numerical approach in Large Eddy Simulation methods, has shown encouraging results in prediction of turbulent flows. In this thesis the governing equations for single phase compressible flow were solved with an ILES approach using a finite volume Godunov-type method without explicit modelling of the subgrid scales. Up to ninth-order limiters were used to achieve high order spatial accuracy. When simulating non chemical reactive flows, the mean flow of a fuel burner was compared with the experimental results and showed good agreement in regions of strong turbulence and recirculation. The one dimensional kinetic energy spectrum was also examined and an ideal k−5/ 3 decay of energy could be seen in a certain range, which increased with grid resolution and order of the limiter. The cut-off wavenumbers are larger than the estimated maximum wavenumbers on the grid, therefore, the numerical dissipation sufficiently accounted for the energy transportation between large and small eddies. The effect of density differences between fuel and air was investigated for a wide range of Atwood number. The mean flow showed that when fuel momentum fluxes are identical the flow structure and the velocity fields were unchanged by Atwood number except for near fuel jet regions. The results also show that the effects of Atwood number on the flow structure can be described with a mixing parameter. In combustion flows simulation, a non filtered Arrhenius model was applied for the chemical source term, which corresponds to the case of the large chemical time scale compared to the turbulent time scale. A methane and air shear flow simulation was performed and the methane reaction rate showed non zero values against all temperature ranges. Small reaction rates were observed in the low temperature range due to the lack of subgrid scale modelling of the chemical source term. Simulation was also performed with fast chemistry approach representing the case of the large turbulent time scale compared to the chemical time scale. The mean flow of burner flames were compared with experimental data and a fair agreement was observed.