An automated approach for performance deviation analysis of evolving software systems

A manutenção e evolução de sistemas de software tornou-se uma tarefa bastante crítica ao longo dos últimos anos devido à diversidade e alta demanda de funcionalidades, dispositivos e usuários. Entender e analisar como novas mudanças impactam os atributos de qualidade da arquitetura de tais sistemas é um pré-requisito essencial para evitar a deterioração de sua qualidade durante sua evolução. Esta tese propõe uma abordagem automatizada para a análise de variação do atributo de qualidade de desempenho em termos de tempo de execução (tempo de resposta). Ela é implementada por um framework que adota técnicas de análise dinâmica e mineração de repositório de software para fornecer uma forma automatizada de revelar fontes potenciais – commits e issues – de variação de desempenho em cenários durante a evolução de sistemas de software. A abordagem define quatro fases: (i) preparação – escolher os cenários e preparar os releases alvos; (ii) análise dinâmica – determinar o desempenho de cenários e métodos calculando seus tempos de execução; (iii) análise de variação – processar e comparar os resultados da análise dinâmica para releases diferentes; e (iv) mineração de repositório – identificar issues e commits associados com a variação de desempenho detectada. Estudos empíricos foram realizados para avaliar a abordagem de diferentes perspectivas. Um estudo exploratório analisou a viabilidade de se aplicar a abordagem em sistemas de diferentes domínios para identificar automaticamente elementos de código fonte com variação de desempenho e as mudanças que afetaram tais elementos durante uma evolução. Esse estudo analisou três sistemas: (i) SIGAA – um sistema web para gerência acadêmica; (ii) ArgoUML – uma ferramenta de modelagem UML; e (iii) Netty – um framework para aplicações de rede. Outro estudo realizou uma análise evolucionária ao aplicar a abordagem em múltiplos releases do Netty, e dos frameworks web Wicket e Jetty. Nesse estudo foram analisados 21 releases (sete de cada sistema), totalizando 57 cenários. Em resumo, foram encontrados 14 cenários com variação significante de desempenho para Netty, 13 para Wicket e 9 para Jetty. Adicionalmente, foi obtido feedback de oito desenvolvedores desses sistemas através de um formulário online. Finalmente, no último estudo, um modelo de regressão para desempenho foi desenvolvido visando indicar propriedades de commits que são mais prováveis a causar degradação de desempenho. No geral, 997 commits foram minerados, sendo 103 recuperados de elementos de código fonte degradados e 19 de otimizados, enquanto 875 não tiveram impacto no tempo de execução. O número de dias antes de disponibilizar o release e o dia da semana se mostraram como as variáveis mais relevantes dos commits que degradam desempenho no nosso modelo. A área de característica de operação do receptor (ROC – Receiver Operating Characteristic) do modelo de regressão é 60%, o que significa que usar o modelo para decidir se um commit causará degradação ou não é 10% melhor do que uma decisão aleatória.

An automated approach for performance deviation analysis of evolving software systems

A manutenção e evolução de sistemas de software tornou-se uma tarefa bastante crítica ao longo dos últimos anos devido à diversidade e alta demanda de funcionalidades, dispositivos e usuários. Entender e analisar como novas mudanças impactam os atributos de qualidade da arquitetura de tais sistemas é um pré-requisito essencial para evitar a deterioração de sua qualidade durante sua evolução. Esta tese propõe uma abordagem automatizada para a análise de variação do atributo de qualidade de desempenho em termos de tempo de execução (tempo de resposta). Ela é implementada por um framework que adota técnicas de análise dinâmica e mineração de repositório de software para fornecer uma forma automatizada de revelar fontes potenciais – commits e issues – de variação de desempenho em cenários durante a evolução de sistemas de software. A abordagem define quatro fases: (i) preparação – escolher os cenários e preparar os releases alvos; (ii) análise dinâmica – determinar o desempenho de cenários e métodos calculando seus tempos de execução; (iii) análise de variação – processar e comparar os resultados da análise dinâmica para releases diferentes; e (iv) mineração de repositório – identificar issues e commits associados com a variação de desempenho detectada. Estudos empíricos foram realizados para avaliar a abordagem de diferentes perspectivas. Um estudo exploratório analisou a viabilidade de se aplicar a abordagem em sistemas de diferentes domínios para identificar automaticamente elementos de código fonte com variação de desempenho e as mudanças que afetaram tais elementos durante uma evolução. Esse estudo analisou três sistemas: (i) SIGAA – um sistema web para gerência acadêmica; (ii) ArgoUML – uma ferramenta de modelagem UML; e (iii) Netty – um framework para aplicações de rede. Outro estudo realizou uma análise evolucionária ao aplicar a abordagem em múltiplos releases do Netty, e dos frameworks web Wicket e Jetty. Nesse estudo foram analisados 21 releases (sete de cada sistema), totalizando 57 cenários. Em resumo, foram encontrados 14 cenários com variação significante de desempenho para Netty, 13 para Wicket e 9 para Jetty. Adicionalmente, foi obtido feedback de oito desenvolvedores desses sistemas através de um formulário online. Finalmente, no último estudo, um modelo de regressão para desempenho foi desenvolvido visando indicar propriedades de commits que são mais prováveis a causar degradação de desempenho. No geral, 997 commits foram minerados, sendo 103 recuperados de elementos de código fonte degradados e 19 de otimizados, enquanto 875 não tiveram impacto no tempo de execução. O número de dias antes de disponibilizar o release e o dia da semana se mostraram como as variáveis mais relevantes dos commits que degradam desempenho no nosso modelo. A área de característica de operação do receptor (ROC – Receiver Operating Characteristic) do modelo de regressão é 60%, o que significa que usar o modelo para decidir se um commit causará degradação ou não é 10% melhor do que uma decisão aleatória.

The Significance of Critical Theory for Restorative Justice in Education

Restorative Justice (rj), a distinctive philosophical approach that seeks to replace punitive, managerial structures of schooling with those that emphasize the building and repairing of relationships (Hopkins 2004) has been embraced in the past two decades by a variety of school systems worldwide in an effort to build safe school communities. Early studies indicate rj holds significant promise, however, proponents in the field identify that theoretical and evidence-based research is falling behind practice. They call for further research to deepen the current understanding of rj that will support its sustainability and transformative potential and allow it to move from the margins to the mainstream of schooling (Braithwaite 2006; Morrison & Ahmed 2006; Sherman & Strang 2007).

The mermaid series of Elizabethan and Jacobean dramatists (1887-1909): a literary and critical history

The Mermaid Series (1887-1909) edited by Havelock Ellis was a major watershed in appreciation of Elizabethan and Jacobean drama. Before it appeared plays were available to general readers in scattered anthologies, large expensive collected editions or in expurgated selections which included only the more lyrical speeches and memorable scenes. Criticism of the drama followed suit; the majority of critics concentrated on the sections which appealed to the romantic and sentimental tastes of nineteenthcentury readers. The two men who conceived the Mermaid Series, John Addington Symonds and Havelock Ellis, approached the drama differently from their contemporaries; Symonds studied a play as a whole work of art and Ellis concentrated on its view of life. Both were unsatisfied with the "select beauties", fragmented approach and wanted readers to have the best plays in their entirety easily available in handy, inexpensive editions. Symonds's awareness of the drama as theatre was combined with a historical perspective allowing him to judge the drama in relation to its own time. He made a lasting but hitherto underestimated contribution to study of Beaumont and Fletcher, Dekker, Marlowe, and Ford. Ellis's work on the drama is overshadowed today by his studies of sex but his concentration on ideas and appreciation of unconventional behaviour enabled him to formulate new views on Ford, Middleton and Chapman. The two other major editors to work on the series, A. C. Swinburne and Arthur Symons had more conventional nineteenth-century approaches. Both were impressionistic critics who were most attracted to the l~nguage of the drama. Swinburne, however, occasionally transcended his fragmented approach and offered significant interpretations of Tourneur, Massinger; 'The .Changeling, Heywood. Symons's range was more limited but his form of impressionism was valuable for its concentration on the aesthetic experience at the heart of a work of art. His most important contributions were the study of Middleton and Massinger. Besides these four major critics numerous lesser writers worked on the series. Their editorial work was valuable and some, notably Ernest Rhys, c. H. Herford and Thomas Dickinson offered criticism of enduring importance. In my first chapter I consider the general availability of texts of the Elizabethan and Jacobean drama in the nineteenth century, the general attitudes towards the drama, and the critical approaches of each of the editors. The subsequent chapters are organized around the volumes of the series. I consider the climate of opinion in which each appeared, assess its critical and editorial contribution and evaluate the work of the other Mermaid editors on the dramatist included in the volume. My study shows that the concept of the Mermaid Series and the work of its editors helped to revolutionize study of the Elizabethan and Jacobean dramatists by providing good texts and by pointing the way to our present view of the plays as whole works of art.

A deep learning-based approach for 3D people tracking

Questa tesi si occupa dell’estensione di un framework software finalizzato all'individuazione e al tracciamento di persone in una scena ripresa da telecamera stereoscopica. In primo luogo è rimossa la necessità di una calibrazione manuale offline del sistema sfruttando algoritmi che consentono di individuare, a partire da un fotogramma acquisito dalla camera, il piano su cui i soggetti tracciati si muovono. Inoltre, è introdotto un modulo software basato su deep learning con lo scopo di migliorare la precisione del tracciamento. Questo componente, che è in grado di individuare le teste presenti in un fotogramma, consente ridurre i dati analizzati al solo intorno della posizione effettiva di una persona, escludendo oggetti che l’algoritmo di tracciamento sarebbe portato a individuare come persone.

Investigating the Tradespace between Increased Automation and Optimal Manning on Aircraft Carrier Decks

With increasing prevalence and capabilities of autonomous systems as part of complex heterogeneous manned-unmanned environments (HMUEs), an important consideration is the impact of the introduction of automation on the optimal assignment of human personnel. The US Navy has implemented optimal staffing techniques before in the 1990's and 2000's with a "minimal staffing" approach. The results were poor, leading to the degradation of Naval preparedness. Clearly, another approach to determining optimal staffing is necessary. To this end, the goal of this research is to develop human performance models for use in determining optimal manning of HMUEs. The human performance models are developed using an agent-based simulation of the aircraft carrier flight deck, a representative safety-critical HMUE. The Personnel Multi-Agent Safety and Control Simulation (PMASCS) simulates and analyzes the effects of introducing generalized maintenance crew skill sets and accelerated failure repair times on the overall performance and safety of the carrier flight deck. A behavioral model of four operator types (ordnance officers, chocks and chains, fueling officers, plane captains, and maintenance operators) is presented here along with an aircraft failure model. The main focus of this work is on the maintenance operators and aircraft failure modeling, since they have a direct impact on total launch time, a primary metric for carrier deck performance. With PMASCS I explore the effects of two variables on total launch time of 22 aircraft: 1) skill level of maintenance operators and 2) aircraft failure repair times while on the catapult (referred to as Phase 4 repair times). It is found that neither introducing a generic skill set to maintenance crews nor introducing a technology to accelerate Phase 4 aircraft repair times improves the average total launch time of 22 aircraft. An optimal manning level of 3 maintenance crews is found under all conditions, the point at which any additional maintenance crews does not reduce the total launch time. An additional discussion is included about how these results change if the operations are relieved of the bottleneck of installing the holdback bar at launch time.

GeoGebraTUTOR : développement d’un système tutoriel autonome pour l’accompagnement d’élèves en situation de résolution de problèmes de démonstration en géométrie plane et genèse d’un espace de travail géométrique idoine

Travaux d'études doctorales réalisées conjointement avec les travaux de recherches doctorales de Nicolas Leduc, étudiant au doctorat en génie informatique à l'École Polytechnique de Montréal.

Empowering development: capabilities and Latin American critical traditions

This thesis theoretically and critically examines the move towards people-centred approaches to development. It offers a critical examination of the work of Amartya Sen using theoretical resources emerging from Latin American traditions. Amartya Sen’s calls to understand Development as Freedom (1999) have significantly influenced mainstream development thinking and practice, constituting the clearest example of people-centred approaches to development today. Overcoming the limitations of previous state-centred notions of development articulated around ideas of economic growth, in Sen’s Capability Approach (CA) development is seen as a process of expanding the real freedoms that people enjoy. In this understanding, the agency of development shifts from the state to individuals and the analytic focus moves from economic growth to individual capabilities. In this manner, this framework is structured towards the central goal of empowerment, wherein the expansion of capabilities is seen both as the means and end of development. Since its inception, the widespread support for the CA has allowed for the expansion of ethical considerations within mainstream development thinking. Even while the remarkable advances offered by Sen’s work should be praised, this thesis argues that these have come with new limitations. These limitations stem from, what is termed here, a “Paradox of Empowerment” that effectively encloses Sen’s approach within Western notions of development. While Sen’s approach is poised to provide a theoretical framework that is built on the expansion of freedom and individual agency, there is little agency here to move beyond the ideas of development fundamentally linked to liberal democracies and market economies. This thesis engages with several critical traditions from Latin America, recovering their often undervalued insights for development thinking. Crucially, this engagement provides the critical framework to illustrate the aforementioned paradox and explore multiple dimensions of empowerment central for contemporary development thinking and practice. In this, the thesis engages Sen’s work with the Liberation Theology of Gustavo Gutierrez, with Paulo Freire’s Critical Pedagogy and with the contemporary discussions of ‘Buen Vivir’ associated with Indigenous philosophies of the Andean region. Throughout its chapters,it uncovers the conceptual baggage within the Paradox of Empowerment in Sen’s work and examines the ethical challenges and boundaries of this approach in relation to the collective dimension of development processes, the possibilities for structural transformation and concerns for sustainability. Progressively engaging the different dimensions of this paradox, this thesis advances the recovery of the transformative potential of the ideas of empowerment for development.

Casting a Critical 'I' Over Caffrey's Irish Ale: Soft Words, Strongly Spoken

By employing a research approach, known as subjective personal introspection - the critical "I" - four co-researchers wrote extensive autobiographical essays on their responses to an advertisement for Caffrey's Irish Ale. By delving in the shamelessly subjective this paper draws out the main themes by comparing, contrasting and critiquing the introspective insights of these four critical "I's". In doing so, it demonstrates that there can be no grounded interpretations of an advertising text, that the critical "I" can yield uniquely illuminating insights, and that its chief power, as a research method, lies in its capacity for creativity, imagination and discovery.

Women, Drug use and Imprisonment. Intersectional Approach

Research on women prisoners and drug use is scarce in our context and needs theoretical tools to understand their life paths. In this article, I introduce an intersectional perspective on the experiences of women in prison, with particular focus on drug use. To illustrate this, I draw on the life story of one of the women interviewed in prison, in order to explore the axes of inequality in the lives of women in prison. These are usually presented as accumulated and articulated in complex and diverse ways. The theoretical tool of intersectionality allows us to gain an understanding of the phenomenon of women prisoners who have used drugs. This includes both the structural constraints in which they were embedded and the decisions they made, considering the circumstances of disadvantage in which they were immersed. This is a perspective which has already been intuitively present since the dawn of feminist criminology in the English-speaking world and can now be developed further due to new contributions in this field of gender studies.

The perception of the African-American community through the eyes of the Hispanic media in the U.S.: a critical discourse analysis of the reporting of the death of Michael Brown

In this paper, 36 English and 38 Spanish news articles were selected from English and Spanish newspapers and magazines published in the U.S.A. from August 2014 to November 2014. All articles discuss the death of Michael Brown, the ensuing protests and police investigations. A discourse analysis shows that there are few differences between reporting by the mainstream and the Hispanic media. Like the mainstream media, the Hispanic media adopts a neutral point of view with regard to the African-American minority. However, it presents a negative opinion with regard to the police. It appears that the Hispanic media does not explicitly side with the African-American community, but rather agrees more with the mainstream media’s opinion and is substantially influenced by it.

Nonequilibrium critical scaling from quantum thermodynamics

The emerging field of quantum thermodynamics is contributing important results and insights into archetypal many-body problems, including quantum phase transitions. Still, the question whether out-of-equilibrium quantities, such as fluctuations of work, exhibit critical scaling after a sudden quench in a closed system has remained elusive. Here, we take a novel approach to the problem by studying a quench across an impurity quantum critical point. By performing density matrix renormalization group computations on the two-impurity Kondo model, we are able to establish that the irreversible work produced in a quench exhibits finite-size scaling at quantum criticality. This scaling faithfully predicts the equilibrium critical exponents for the crossover length and the order parameter of the model, and, moreover, implies a new exponent for the rescaled irreversible work. By connecting the irreversible work to the two-impurity spin correlation function, our findings can be tested experimentally.

Towards a knowledge-based approach for effective decision-making in railway safety

Purpose – This paper aims to contribute towards understanding how safety knowledge can be elicited from railway experts for the purposes of supporting effective decision-making. Design/methodology/approach – A consortium of safety experts from across the British railway industry is formed. Collaborative modelling of the knowledge domain is used as an approach to the elicitation of safety knowledge from experts. From this, a series of knowledge models is derived to inform decision-making. This is achieved by using Bayesian networks as a knowledge modelling scheme, underpinning a Safety Prognosis tool to serve meaningful prognostics information and visualise such information to predict safety violations. Findings – Collaborative modelling of safety-critical knowledge is a valid approach to knowledge elicitation and its sharing across the railway industry. This approach overcomes some of the key limitations of existing approaches to knowledge elicitation. Such models become an effective tool for prediction of safety cases by using railway data. This is demonstrated using passenger–train interaction safety data. Practical implications – This study contributes to practice in two main directions: by documenting an effective approach to knowledge elicitation and knowledge sharing, while also helping the transport industry to understand safety. Social implications – By supporting the railway industry in their efforts to understand safety, this research has the potential to benefit railway passengers, staff and communities in general, which is a priority for the transport sector. Originality/value – This research applies a knowledge elicitation approach to understanding safety based on collaborative modelling, which is a novel approach in the context of transport.

Conservative fluid management or deresuscitation for patients with sepsis or acute respiratory distress syndrome following the resuscitation phase of critical illness: a systematic review and meta-analysis

Background

It is unknown whether a conservative approach to fluid administration or deresuscitation (active removal of fluid using diuretics or renal replacement therapy) is beneficial following haemodynamic stabilisation of critically ill patients.

Purpose

To evaluate the efficacy and safety of conservative or deresuscitative fluid strategies in adults and children with acute respiratory distress syndrome (ARDS), sepsis or systemic inflammatory response syndrome (SIRS) in the post-resuscitation phase of critical illness.

Methods

We searched Medline, EMBASE and the Cochrane central register of controlled trials from 1980 to June 2016, and manually reviewed relevant conference proceedings from 2009 to the present. Two reviewers independently assessed search results for inclusion and undertook data extraction and quality appraisal. We included randomised trials comparing fluid regimens with differing fluid balances between groups, and observational studies investigating the relationship between fluid balance and clinical outcomes.

Results

Forty-nine studies met the inclusion criteria. Marked clinical heterogeneity was evident. In a meta-analysis of 11 randomised trials (2051 patients) using a random-effects model, we found no significant difference in mortality with conservative or deresuscitative strategies compared with a liberal strategy or usual care [pooled risk ratio (RR) 0.92, 95 % confidence interval (CI) 0.82–1.02, I2 = 0 %]. A conservative or deresuscitative strategy resulted in increased ventilator-free days (mean difference 1.82 days, 95 % CI 0.53–3.10, I2 = 9 %) and reduced length of ICU stay (mean difference −1.88 days, 95 % CI −0.12 to −3.64, I2 = 75 %) compared with a liberal strategy or standard care.

Conclusions

In adults and children with ARDS, sepsis or SIRS, a conservative or deresuscitative fluid strategy results in an increased number of ventilator-free days and a decreased length of ICU stay compared with a liberal strategy or standard care. The effect on mortality remains uncertain. Large randomised trials are needed to determine optimal fluid strategies in critical illness.

Collaborative Filtering with Data Classification : A Combined Approach to Hotel Recommendation Systems

Recommendation systems aim to help users make decisions more efficiently. The most widely used method in recommendation systems is collaborative filtering, of which, a critical step is to analyze a user's preferences and make recommendations of products or services based on similarity analysis with other users' ratings. However, collaborative filtering is less usable for recommendation facing the "cold start" problem, i.e. few comments being given to products or services. To tackle this problem, we propose an improved method that combines collaborative filtering and data classification. We use hotel recommendation data to test the proposed method. The accuracy of the recommendation is determined by the rankings. Evaluations regarding the accuracies of Top-3 and Top-10 recommendation lists using the 10-fold cross-validation method and ROC curves are conducted. The results show that the Top-3 hotel recommendation list proposed by the combined method has the superiority of the recommendation performance than the Top-10 list under the cold start condition in most of the times.