Tese de Mestrado Integrado. Engenharia Informática e Computação. Universidade do Porto. Faculdade de Engenharia. 2010

Atmospheric aerosols deteriorate visibility and pose a significant risk to human health. The global fluxes of secondary organic aerosols (SOA) that form in the atmosphere from aromatic hydrocarbons are poorly constrained and highly uncertain. The lack of molecular tracers to quantify anthropogenic SOA (ASOA) in part limits the understanding of its abundance and variability, and results in a systematic underestimation of the role of ASOA in the atmosphere. The research presented in this thesis advances the knowledge about ASOA through the i) development of new and advanced methods to quantify potential ASOA tracers, ii) evaluation of their suitability as tracers for ASOA, and iii) application of the validated tracers to assess the spatial, diurnal and seasonal variation of ASOA in three urban environments. In this research, a greater understanding of the role of ASOA is gained through the expansion of tracers for SOA from aromatic hydrocarbons. An analytical method to quantify furandiones, which are produced in high yields from the photooxidation of aromatic hydrocarbons, was developed and enabled the first ambient measurements of furandiones. The optimized method allows for the simultaneous extraction of primary source tracers (e.g., polycyclic aromatic hydrocarbons, hopanes, levoglucosan) and other potential ASOA tracers (e.g., 2,3-dihydroxy-4-oxopentanoic acid [DHOPA], benzene dicarboxylic acids, and nitromonoaromatics). The systematic evaluation of potential ASOA tracers by their detectability, gas-particle partitioning, and specificity revealed that DHOPA, phthalic acid, 4-methylphthalic acids, and some nitromonoaromatics are good ASOA tracers because they are specific to aromatic hydrocarbon photooxidation, readily detected in ambient air, and substantially partition to the particle phase under ambient conditions. These tracers are thus recommended for use in field studies to estimate ASOA contributions to atmospheric aerosol relative to other sources. ASOA was determined to be a significant contributor to PM2.5 organic carbon (OC) in three urban environments. In the industrial Houston Ship Channel area in Houston, TX, ASOA contributed 28% of OC, while biogenic SOA (BSOA) contributed 11%. Diurnally, ASOA peaked during daytime and was largely associated with motor vehicle emissions. In Shenzhen, a megacity in China, 13-23% of OC mass was attributed to ASOA, three folds higher than BSOA. When China controlled the emissions from fossil fuel-related sources, the ASOA contribution to OC reduced by 42-75% and visibility remarkably improved. In downtown Atlanta, GA, ASOA contributed 29% and 16% of OC during summer and winter, respectively. ASOA dominates over BSOA during winter, while high biogenic VOC fluxes made BSOA the major SOA source in Atlanta, GA during summertime. These results indicate the high abundance of ASOA in urban air that has potential to be reduced by modification of anthropogenic activities. Overall, the work presented in this dissertation advances the knowledge about the abundance and variation of ASOA in urban atmospheres through the development of quantification methods and expansion of ASOA tracers. These tracers improve source apportionment of ASOA in receptor based models, which can ultimately aid in developing and implementing effective strategies for air quality management.

Ce travail a eu pour objectif d’améliorer notre compréhension des processus de formation et d’évolution des aérosols organiques secondaires (AOS) en étudiant les réactions susceptibles d’expliquer la présence d’espèces « mixtes » organosoufrées observées récemment dans l’aérosol atmosphérique. Les composés organiques volatils et en particulier les monoterpènes ont été identifiés comme étant des précurseurs potentiellement importants d’organosulfates dans l’atmosphère. Cependant, les mécanismes de formation de ces derniers ne sont pas encore bien compris. Seule une étude au niveau moléculaire et ciblée sur une réaction multiphasique unique, peut donner accès à des mécanismes réactionnels détaillés. Ainsi, les réactions entre l’α-pinène et quatre produits d’oxydation associés (α-pinène oxyde, myrténal, isopinocamphéol et pinanediol), avec des particules modèles de sulfate d’ammonium ont été étudiées individuellement dans le but de documenter la formation d’organosulfates. L’effet de l’humidité relative et celui de l’acidité des particules sur ces réactions ont été étudiés. La quantification en ligne des composés organiques volatils a été effectuée à l’aide d’un spectromètre de masse à transfert protonique. L’identification des structures moléculaires des organosulfates, formés en phase particulaire, a été effectuée par chromatographie liquide couplée à la spectrométrie de masse en tandem. Deux approches complémentaires, impliquant des expériences en réacteur quasi-statique et en chambre de simulation atmosphérique, ont permis de mettre en évidence la formation d’organosulfates mais également de proposer des mécanismes réactionnels pour l’ensemble des composés oxydés étudiés. / This work deals with the formation and aging processes of secondary organic aerosol (SOA). More precisely, the objective was to document organosulfate formation, recently identified in ambient aerosol. Volatile organic compounds (VOCs) such as monoterpenes have been recognized as potentially important precursors of organosulfates in the atmosphere. However, organosulfate formation is not yet well understood. Reliable chemical mechanisms can only be accessible when studying individual reactions at the molecular level. In this work, organosulfate formation was studied for the reactions of α-pinene and associated oxidized species (α-pinene oxide, myrtenal, isopinocampheol and pinanediol) with acidified ammonium sulfate particles. On-line quantification of VOCs was carried out using proton-transfer-reaction mass spectrometry. Identification of products in the particulate phase has been performed using liquid chromatography coupled with tandem mass spectrometry. Experiments from quasi-static reactor and atmospheric simulation chamber experiments are compared and discussed, allowing to propose chemical mechanisms explaining organosulfate formation for the heterogeneous reactions of interest.

Service-Oriented Architecture (SOA) represents an emerging architectural approach that is able to tackle challenges in the contemporary service-based economy, in which the global market revenues are shifting from the manufacture of traditional off-the-shelf products to the provision of diversified services that suffice for customers’ needs. In such a service-based economy, one can envisage an entirely “service-oriented” world, where a massive number of distributed services with different natures and capabilities are provided by various professionals around the world. Problems arise when business applications demand desirable services through different sources and providers that are appropriate for their own benefits and preferences. Therefore, it can be very challenging to design an SOA infrastructure that enables users to exploit this great level of service heterogeneity and quantity. One of the key issues in service-oriented architecture is to achieve efficient service discovery and loosely-coupled service distribution while maintaining a satisfactory degree of scalability, usability, and Web consistency. This thesis deals with SOA infrastructure-level design and implementation issues. It approaches this SOA infrastructure within the scope of Web services, which capture an important, and perhaps the best, ‘realisation’ of SOA. It investigates and formulates how public Web services distributed across the World Wide Web can be augmented by a software platform that enables scalable, user-centred,semantic-enabled, and integration-oriented service retrieval, selection, and matching. The primary goal of this thesis is thus to propose a conceptual framework of an enhanced SOA infrastructure with regard to service distribution and discovery. / It also aims to design and implement a platform (PWSP), by means of which a large number of public Web services on the Web can be distributed based on service demands, retrieved based on service descriptions, selected based on service qualities, and matched based on service messages in a user-centred, scalable, and Web-consistent manner without augmenting existing Web services standards.

Service-oriented architectures (SOA), and in particular Web services, have quickly become a popular technology to connect applications both within and across enterprise boundaries. However, as services are increasingly used to implement critical functionality, security has become an important concern impeding the widespread adoption of SOA. Trust negotiation is an approach to access control that may be applied in scenarios where service requesters are often unknown in advance, such as for services available via the public Internet. Rather than relying on requesters' identities, trust negotiation makes access decisions based on the level of trust established between the requester and the provider in a negotiation, during which the parties exchange credentials, which are signed assertions that describe some attributes of the owner. However, managing the evolution of trust negotiation policies is a difficult problem that has not been sufficiently addressed to date. Access control policies have a lifecycle, and they are revised based on applicable business policies. Additionally, because a trust relationship established in a trust negotiation may be long lasting, their evolution must also be managed. Simply allowing a negotiation to continue according to an old policy may be undesirable, especially if new important constraints have been added. In this thesis, we introduce a model-driven trust negotiation framework for service-oriented applications. The framework employs a model for trust negotiation, based on state machines, that allows automated generation of the control structures necessary to enforce trust negotiation policies from the visual model of the policy. Our policy model also supports lifecycle management. We provide sets of operations to modify policies and to manage ongoing negotiations, and operators for identifying and managing impacts of changes to trust negotiation policies on ongoing trust negotiations. The framework presented in the thesis has been implemented in the Trust-Serv prototype, which leverages industry specifications such as WS-Security and WS-Trust to offer a container-centric mechanism for deploying trust negotiation that is transparent to the services being protected.

Pour devenir ou rester compétitif, un opérateur télécom doit constamment enrichir ou adapter son offre de services. Cette recherche permanente d'innovation implique de rendre agiles les processus de création de service. Par agilité nous entendons non seulement la capacité à mettre rapidement sur le marché de nouvelles idées de service mais également de s'assurer de leur évolution dans un environnement technologique changeant. Dans ce mémoire de thèse nous défendons l'idée qu'une utilisation pragmatique et combinée des principes du SOA avec les technologies d'ingénierie des modèles peut être un facteur clef pour l'optimisation du processus de création de services et pour répondre aux exigences de l'agilité. L'approche que nous recommandons dans le cas des services de télécommunications que nous avons étudié (les services composites intégrés et les services vocaux) c'est d'abord d'utiliser des langages dédiés (DSL) graphiques et/ou textuels pour la spécification de haut niveau des services, ensuite d'exploiter ces spécifications dans des environnements de création et d'exécution (frameworks) orientés modèles supportant nativement le DSL, afin de permettre le test et la simulation au plus tôt des fonctionnalités du service via des itérations rapides. Enfin une automatisation importante du déploiement vers les plates-formes de production (serveurs d'application) et les terminaux mobiles (code client) via le développement de transformateurs dédiés. Le travail présenté dans cette thèse est validé par plusieurs expérimentations et démonstrations portant sur des services vocaux et des services de télécommunication intégrés composites (exploitant des ressources télécom et des facilités issues de l'industrie informatique).

No description available.

<p>The starting point of this paper has to do with rapid changes within the information technology and the need for agile and fast systems. The primary goal is to investigate what happens with recordkeeping practices in agile environments like service oriented architecture (SOA). It is in the possible transfer between IT architecture and digital archive the area of this paper resides. The paper relates to the Records Continuum model by which records will be considered historical and active at the time of creation. In the Records Continuum model recordkeeping practices and archival requirements will have to be taken into account at the time of creation.</p><p>This paper concerns SOA from the perspective of Archival and Information science. It describes the different parts that make it possible to achieve a SOA with emphasis on those parts which have the most impact on the requirements of a digital archive. The main requirements discussed in this paper are the principle of provenance, the need to ensure that records remain authentic, reliable and keep their integrity and usability over time. The issue of keeping track of information and activities in a SOA is also discussed. It is established that records which need to fulfil the requirements mentioned above do exists in a SOA. The purpose of this paper is to investigate whether or not the principle of provenance and the archival requirements will be affected by SOA, and whether or not the requirements can be fulfilled over time.</p><p>Information collection for this paper is basically through studies of literature and information gathering on the Internet. The method is descriptive and comparison between the information gathered has been made. In addition one short interview has been undertaken with Skatteverket, a government that are in the process of implementing both SOA and a digital archive. The main purpose with the interview was to find out if there are any collaboration between SOA and the digital archive at Skatteverket.</p><p>The results indicate that a lot of the problem concerning preservation of digital records over time also applies for SOA, such as the lack of sustainable format and media and the potential loss of information. However some successful implementations of digital archives based on the OAIS-model with SOA as tool for realising the digital archive has been found. The archival requirements and the principle of provenance will be affected by SOA but it is only when there is a connection between SOA and a digital archive that it is possible to secure some of the archival requirements.</p>

L'avantage majeur qu'offrent les services Web est le fait qu'ils reposent sur des standards et les technologies du Web pour interagir en s'échangeant des messages. A part les séquences de messages, d'autres facteurs affectent l'interopérabilité des services Web, telles que les contraintes temporelles qui spécifient les délais nécessaires pour échanger des messages. La thèse rapportée dans ce manuscrit étudie l'impact de ces propriétés dans la composition de services Web. La considération de telles propriétés soulève plusieurs problèmes auxquels on a essayé d'apporter une solution. Le premier aspect consiste à définir un modèle qui tienne compte des abstractions nécessaires afin de pouvoir analyser et synthétiser une composition, à savoir les messages, les données, les contraintes de données, les propriétés temporelles et l'aspect asynchrone des communications des services. En se basant sur ce modèle, le deuxième problème consiste à proposer une approche d'analyse de compatibilité. Cette analyse vise à caractériser la compatibilité ou la non-compatibilité des services Web et ce en prenant en considération les abstractions précédemment citées. Nous étudions particulièrement l'impact des propriétés temporelles dans une chorégraphie dans laquelle les services Web supportent des communications asynchrones. Nous proposons une démarche basée sur le model checking qui permet de détecter les éventuels conflits temporisés qui peuvent surgir dans une chorégraphie. Finalement, le dernier problème auquel nous nous intéressons est celui de la construction d'une composition qui essaie de répondre au besoin du client et ce en prenant en compte les aspects temporels. L'approche que l'on propose est basée sur la génération d'un médiateur pour essayer, quand c'est possible, de contourner les incompatibilités temporisées et non-temporisées qui peuvent surgir lors d'une collaboration. Des mécanismes et des algorithmes ont été développés afin de mettre en oeuvre ces objectifs.

<p>Today’s competitive business environment forces companies to introduce new product and process innovations at an increasing pace. Almost every aspect of the modern business is supported by information technology systems which, consequently, must evolve at the same pace as the business. A company’s strategic view on IT reflects the strategic importance of IT in the organization, both in terms of the opportunities IT is expected to create and the commitment to IT the business organization is willing to make.</p><p>SOA is an emerging concept which aims to structure IT in a more flexible manner. The basic idea is to encapsulate distinct units of business logic in reusable services, which can be combined to support business processes. The term service granularity refers to the amount of logic contained in a service. Even though there is immense hype around SOA today, the concept of service granularity is still relatively unexplored. The service should be coarse grained enough to be reusable, but at the same time specific enough to fit the process. Most SOA literature avoids the subject as being too implementation specific and seldom makes any attempt to concretize the rather abstract term.</p><p>The research was conducted at Handelsbanken, which for years has worked with service-oriented principles. The researchers have been given the opportunity to closely analyze the bank’s service initiative. In order to gain an understanding beyond merely technical aspects a rich case study was built, based on interviews with professionals at all levels of the organization.</p><p>The research objective was divided in three parts. The first part was to factorize the notion of service granularity, or in other words to find a number of factors which together precisely describe the granularity of a service. The second part was to explicate how the factors are interrelated, i.e. how changing one factor will affect the others. The final part of the objective was to explain how an organization’s strategic view on IT affects the optimal service granularity.</p><p>It was found that an organization’s strategic view on IT affects the amount of complexity the organization is able to handle, limiting the optimal SOA granularity, which can be precisely described using three factors: reach, range and realm. Reach defines the locations and people the service is capable of connecting, range defines how much functionality the service offers, and realm defines what kind of functionality the service offers.</p>