2,221 research outputs found

    The future of UAS: standards, regulations, and operational experiences [workshop report]

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    This paper presents the outcomes of "The Future of UAS: Standards, Regulations and Operational Experiences" workshop, held on the 7th and 8th of December, 2006 in Brisbane, Queensland, Australia. The goal of the workshop was to identify recent international activities in the Unmanned Airborne Systems (UAS) airspace integration problem. The workshop attracted a broad cross-section of the UAS community, including: airspace and safety regulators, developers, operators and researchers. The three themes of discussion were: progress in the development of standards and regulations, lessons learnt from recent operations, and advances in new technologies. This paper summarises the activities of the workshop and explores the important outcomes and trends as perceived by the authors

    Bitcoin, the controversial cryptocurrency: an insightful overview and its context in the portuguese market

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    Before Bitcoin's appearance, all the payment systems had faced the requirement of being controlled by an entity, as none had shown the ability to perform in a decentralized structure. Bitcoin is also a digital currency and consequently has no intrinsic value, however it has shown an enormous price increase over the past few years, having that growth a special emphasis in the current year. Therefore, Bitcoin emerges as a disruptor in the current financial system. This dissertation has the main objective of analysing the key concepts of Bitcoin from which the most controversial topics emerge. Then, those topics are furtherly scrutinized by developing a quantitative and qualitative research always regarding both present and future impacts of Bitcoin. The research includes statistical data from Bitcoin and other financial data providers. Additionally, and due to the lack of literature comprising the Portuguese market, a special attention is given to this country. Despite the lack of credibility among most financial leaders which has consisted of a limitation to Bitcoin's implementation process, this cryptocurrency is a technological landmark and, so far, shows no signs of slowing down.Antes do aparecimento da Bitcoin, todos os sistemas de pagamento enfrentavam a condição de serem controlados por uma entidade, uma vez que nenhum tinha mostrado capacidade para atuar numa estrutura descentralizada. A Bitcoin é também uma moeda digital e como tal não tem valor intrínseco, no entanto o seu preço tem tido um enorme aumento nos últimos anos, com especial ênfase no ano corrente. Deste modo, a Bitcoin surge como um disruptor do atual sistema financeiro. Esta dissertação tem como principal objetivo a análise dos conceitos fundamentais da Bitcoin, dos quais surgem os tópicos mais controversos. Após essa fase, esses tópicos serão aprofundados através do desenvolvimento de uma pesquisa quantitativa e qualitativa, tendo sempre em consideração impactos atuais e futuros da Bitcoin. Esta pesquisa inclui dados estatísticos apresentados por intermediários da Bitcoin e outros fornecedores de dados financeiros. Adicionalmente, e devido à ausência de literatura que inclua o mercado Português, este será analisado de forma mais detalhada. Apesar da falta de credibilidade junto dos principais líderes financeiros o que tem consistido numa limitação ao processo de implementação da Bitcoin, esta criptomoeda é um marco tecnológico e, até agora, não mostra sinais de abrandamento

    Sustaining a Vertically Disintegrated Network through a Bearer Service Market

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    Based upon the Internet perspective, this chapter will attempt to clarify and revise several ideas about the separation between infrastructure facilities and service offerings in digital communications networks. The key notions that we will focus on in this paper are: i) the bearer service as a technology-independent interface which exports blind network functionality to applications development; ii) the sustainability of an independent market for bearer service and the organizational consequences associated with such a market

    Economic Perspective on Cloud Computing: Three Essays

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    Improvements in Information Technology (IT) infrastructure and standardization of interoperability standards among heterogeneous Information System (IS) applications have brought a paradigm shift in the way an IS application could be used and delivered. Not only an IS application can be built using standardized component but also parts of it can be hosted by different organizations in different locations provided it can be accessed using the Internet. This dissertation is an attempt to uncover unique aspects of this phenomenon known as Software as a Service (SaaS). The first essay examines design decision making by SaaS providers by analyzing effects of two non-functional attributes of an IS Application - modularity and architectural performance. We model the relationship of the two attributes with factors such as demand, price, and user\u27s preference. The model includes marginal cost and maintenance cost to recognize the service aspect of SaaS. Our results show the optimal values of various decision variables while taking into account user\u27s sensitivity to modularity, architectural performance and price. The service component in cloud computing necessitates that the service providers plan for requisite delivery capacity. The second essay addresses optimal infrastructure capacity planning while taking into account the opportunity cost of having low capacity and cost of unused capacity in the case of high capacity. We develop a model which provides insight to a SaaS provider on optimal capacity planning of IT infrastructure when faced with a variable demand and performance expectations. The third essay focuses on financial risks faced by SaaS providers in the context of provider\u27s risk tolerance. We analyze the financial risk of provider\u27s decision making on pricing, capacity and other factors that may lead to financial risk as they are based on incomplete information. We built a model using Mean Variance Analysis theory for investigating the effect of provider\u27s risk tolerance on infrastructure capacity planning while taking into account modularity in software architecture and operational performance. This dissertation extends our understanding of significant issues facing a SaaS provider. The models presented here can form the basis for an extensive exploration of the phenomenon of SaaS specifically and Cloud Computing in general

    Literature based Cyber Security Topics: Handbook

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    Cyber security is the practice of protecting systems, networks, and programs from digital attacks. These cyber attacks are usually aimed at accessing, changing, or destroying sensitive information; extorting money from users; or interrupting normal business processes. Cloud computing has emerged from the legacy data centres. Consequently, threats applicable in legacy system are equally applicable to cloud computing along with emerging new threats that plague only the cloud systems. Traditionally the data centres were hosted on-premises. Hence, control over the data was comparatively easier than handling a cloud system which is borderless and ubiquitous. Threats due to multi-tenancy, access from anywhere, control of cloud, etc. are some examples of why cloud security becomes important. Considering the significance of cloud security, this work is an attempt to understand the existing cloud service and deployment models, and the major threat factors to cloud security that may be critical in cloud environment. It also highlights various methods employed by the attackers to cause the damage. Cyber-attacks are highlighted as well. This work will be profoundly helpful to the industry and researchers in understanding the various cloud specific cyber-attack and enable them to evolve the strategy to counter them more effectively

    Loop detection and prevention mechanism in multiprotocol label switching

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    The extended color thread algorithm is based on running a thread hop by hop before the labels are distributed inside a MPLS Cloud Since the path for the data packets is set beforehand, the loop formation occurs at the control path. The shortest paths between selected source and destination have been calculated using Dijkstra\u27s shortest path algorithm and threads are allowed to extend through the routers. With the passage of each next hop, a distributed procedure is executed within the thread, generating a unique color at nodes. This keeps a track on router\u27s control path and at the same time ensures that no loop formation occurs. In loop prevention mode, a router transmits a label mapping, when it rewinds the thread for that particular LSP. Likewise, if a router operates in loop detection mode, it returns a label-mapping message without a thread object, after receiving a colored thread. The scheme is a loop prevention scheme, thus, ensuring loop detection and loop mitigation. The same algorithm is then extended to a proposed MPLS environment with global label space. (Abstract shortened by UMI.)

    Suriname: Reconciling agricultural development and conservation of unique natural wealth

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    National and transboundary adverse effects of competition for land are being increasingly recognized by researchers and decision-makers, however the consideration of these impacts within national planning strategies is not yet commonplace. To estimate how increasing agricultural production can be conciliated with protection of natural resources at the national scale, we analyzed current land use in Suriname, and investigated opportunities for, and constraints to developing a sustainable agricultural sector. Suriname is a remarkable case study. To date, Suriname has retained most of its natural resources with forest areas covering over 90% of the country. Surinamese forests combine extremely high levels of both biodiversity and carbon, making them top priority from a global ecosystem services perspective. Among other national and international pressures from increased demand for agricultural products, the country is also considering significant expansion of agricultural output to both diminish imports and become a ‘bread basket’ for the Caribbean region, which collectively may pose risks to natural resources. In this study, combining locally-obtained primary data, expert consultation and secondary data from the Food and Agriculture Organization we analyzed a range of scenarios, we show the complexities associated with current land management and we discuss alternatives for developing a sustainable agricultural sector in Suriname. We show that Suriname can increase the production of rice, which is the most important agricultural activity in the country, without expanding rice area. Rather, future increase in rice production could be promoted through an increase in rice productivity, and the employment of more environmentally-favorable management methods, in order to both diminish pollution and avoid encroachment of the agriculture into pristine areas. Further, we show a potential to both contribute to greening of the agricultural sector and to higher economic returns through expanding the production of ‘safe food’ and through possible development of organic agriculture in Suriname. If Suriname develops a ‘greener’ agricultural sector, it may both increase economic returns from the agricultural sector and benefit from continuing protection of natural resources. Because most of Suriname forests present top levels of carbon and biodiversity, the country could benefit from so-called ‘early-action’ Reducing Emissions from Deforestation and Forest Degradation (REDD) finance, which is already being paid mostly through bilateral agreements. Further, by adopting land-use planning that protects natural resources, Suriname may be in extraordinary position to benefit from both improved-quality agricultural production and from incentives to conserve forest carbon and biodiversity, such as payments for ecosystem services. Given the high stakes and the severe lack of both primary data and applied analyses in Suriname, further research focused on better informing land-use policies would be a valuable investment for the country. Although this analysis was performed for Suriname, conclusions drawn here are transferrable and may assist formulation of policy recommendations for land use elsewhere

    Issues and Challenges for Network Virtualisation

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    In recent years, network virtualisation has been of great interest to researchers, being a relatively new and major paradigm in networking. This has been reflected in the IT industry where many virtualisation solutions are being marketed as revolutionary and purchased by enterprises to exploit these promised performances. Adversely, there are certain drawbacks like security, isolation and others that have conceded the network virtualisation. In this study, an investigation of the different state-of-the-art virtualisation technologies, their issues and challenges are addressed and besides, a guideline for a quintessential Network Virtualisation Environment (NVE) is been proposed. A systematic review was effectuated on selectively picked research papers and technical reports. Moreover a comparative study is performed on different Network Virtualisation technologies which include features like security, isolation, stability, convergence, outlay, scalability, robustness, manageability, resource management, programmability, flexibility, heterogeneity, legacy Support, and ease of deployment. The virtualisation technologies comprise Virtual Private Network (VPN), Virtual Local Area Network (VLAN), Virtual Extensible Local Area Network (VXLAN), Software Defined Networking (SDN) and Network Function Virtualisation (NFV). Conclusively the results exhibited the disparity as to the gaps of creating an ideal network virtualisation model which can be circumvented using these as a benchmark

    Towards a cloud enabler : from an optical network resource provisioning system to a generalized architecture for dynamic infrastructure services provisioning

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    This work was developed during a period where most of the optical management and provisioning system where manual and proprietary. This work contributed to the evolution of the state of the art of optical networks with new architectures and advanced virtual infrastructure services. The evolution of optical networks, and internet globally, have been very promising during the last decade. The impact of mobile technology, grid, cloud computing, HDTV, augmented reality and big data, among many others, have driven the evolution of optical networks towards current service technologies, mostly based on SDN (Software Defined Networking) architectures and NFV(Network Functions Virtualisation). Moreover, the convergence of IP/Optical networks and IT services, and the evolution of the internet and optical infrastructures, have generated novel service orchestrators and open source frameworks. In fact, technology has evolved that fast that none could foresee how important Internet is for our current lives. Said in other words, technology was forced to evolve in a way that network architectures became much more transparent, dynamic and flexible to the end users (applications, user interfaces or simple APIs). This Thesis exposes the work done on defining new architectures for Service Oriented Networks and the contribution to the state of the art. The research work is divided into three topics. It describes the evolution from a Network Resource Provisioning System to an advanced Service Plane, and ends with a new architecture that virtualized the optical infrastructure in order to provide coordinated, on-demand and dynamic services between the application and the network infrastructure layer, becoming an enabler for the new generation of cloud network infrastructures. The work done on defining a Network Resource Provisioning System established the first bases for future work on network infrastructure virtualization. The UCLP (User Light Path Provisioning) technology was the first attempt for Customer Empowered Networks and Articulated Private Networks. It empowered the users and brought virtualization and partitioning functionalities into the optical data plane, with new interfaces for dynamic service provisioning. The work done within the development of a new Service Plane allowed the provisioning of on-demand connectivity services from the application, and in a multi-domain and multi-technology scenario based on a virtual network infrastructure composed of resources from different infrastructure providers. This Service Plane facilitated the deployment of applications consuming large amounts of data under deterministic conditions, so allowing the networks behave as a Grid-class resource. It became the first on-demand provisioning system that at lower levels allowed the creation of one virtual domain composed from resources of different providers. The last research topic presents an architecture that consolidated the work done in virtualisation while enhancing the capabilities to upper layers, so fully integrating the optical network infrastructure into the cloud environment, and so providing an architecture that enabled cloud services by integrating the request of optical network and IT infrastructure services together at the same level. It set up a new trend into the research community and evolved towards the technology we use today based on SDN and NFV. Summing up, the work presented is focused on the provisioning of virtual infrastructures from the architectural point of view of optical networks and IT infrastructures, together with the design and definition of novel service layers. It means, architectures that enabled the creation of virtual infrastructures composed of optical networks and IT resources, isolated and provisioned on-demand and in advance with infrastructure re-planning functionalities, and a new set of interfaces to open up those services to applications or third parties.Aquesta tesi es va desenvolupar durant un període on la majoria de sistemes de gestió de xarxa òptica eren manuals i basats en sistemes propietaris. En aquest sentit, la feina presentada va contribuir a l'evolució de l'estat de l'art de les xarxes òptiques tant a nivell d’arquitectures com de provisió d’infraestructures virtuals. L'evolució de les xarxes òptiques, i d'Internet a nivell mundial, han estat molt prometedores durant l'última dècada. L'impacte de la tecnologia mòbil, la computació al núvol, la televisió d'alta definició, la realitat augmentada i el big data, entre molts altres, han impulsat l'evolució cap a xarxes d’altes prestacions amb nous serveis basats en SDN (Software Defined Networking) i NFV (Funcions de xarxa La virtualització). D'altra banda, la convergència de xarxes òptiques i els serveis IT, junt amb l'evolució d'Internet i de les infraestructures òptiques, han generat nous orquestradors de serveis i frameworks basats en codi obert. La tecnologia ha evolucionat a una velocitat on ningú podria haver predit la importància que Internet està tenint en el nostre dia a dia. Dit en altres paraules, la tecnologia es va veure obligada a evolucionar d'una manera on les arquitectures de xarxa es fessin més transparent, dinàmiques i flexibles vers als usuaris finals (aplicacions, interfícies d'usuari o APIs simples). Aquesta Tesi presenta noves arquitectures de xarxa òptica orientades a serveis. El treball de recerca es divideix en tres temes. Es presenta un sistema de virtualització i aprovisionament de recursos de xarxa i la seva evolució a un pla de servei avançat, per acabar presentant el disseny d’una nova arquitectura capaç de virtualitzar la infraestructura òptica i IT i proporcionar serveis de forma coordinada, i sota demanda, entre l'aplicació i la capa d'infraestructura de xarxa òptica. Tot esdevenint un facilitador per a la nova generació d'infraestructures de xarxa en el núvol. El treball realitzat en la definició del sistema de virtualització de recursos va establir les primeres bases sobre la virtualització de la infraestructura de xarxa òptica en el marc de les “Customer Empowered Networks” i “Articulated Private Networks”. Amb l’objectiu de virtualitzar el pla de dades òptic, i oferir noves interfícies per a la provisió de serveis dinàmics de xarxa. En quant al pla de serveis presentat, aquest va facilitat la provisió de serveis de connectivitat sota demanda per part de l'aplicació, tant en entorns multi-domini, com en entorns amb múltiples tecnologies. Aquest pla de servei, anomenat Harmony, va facilitar el desplegament de noves aplicacions que consumien grans quantitats de dades en condicions deterministes. En aquest sentit, va permetre que les xarxes es comportessin com un recurs Grid, i per tant, va esdevenir el primer sistema d'aprovisionament sota demanda que permetia la creació de dominis virtuals de xarxa composts a partir de recursos de diferents proveïdors. Finalment, es presenta l’evolució d’un pla de servei cap una arquitectura global que consolida el treball realitzat a nivell de convergència d’infraestructures (òptica + IT) i millora les capacitats de les capes superiors. Aquesta arquitectura va facilitar la plena integració de la infraestructura de xarxa òptica a l'entorn del núvol. En aquest sentit, aquest resultats van evolucionar cap a les tendències actuals de SDN i NFV. En resum, el treball presentat es centra en la provisió d'infraestructures virtuals des del punt de vista d’arquitectures de xarxa òptiques i les infraestructures IT, juntament amb el disseny i definició de nous serveis de xarxa avançats, tal i com ho va ser el servei de re-planificació dinàmicaPostprint (published version
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