3,482 research outputs found

    High speed rail transport valuation

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    The present paper investigates the optimal timing of investment for a high speed rail (HSR) project, in an uncertain environment, using a real options analysis (ROA) framework. It develops a continuous time framework with stochastic demand that allows for the determination of the optimal timing of investment and the value of the option to defer in the overall valuation of the project. The modelling approach used is based on the differential utility provided to railway users by the HSR service.info:eu-repo/semantics/publishedVersio

    High speed rail transport valuation and policy decisions

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    The present paper investigates the process of decision making regarding the optimal timing to invest in the high speed rail (HSR) project, under uncertainty, using the real options analysis (ROA) framework. It’s developed a continuous time framework that allows a solution to the problem concerning the optimal timing to invest and to value the impact of the option to defer in the overall valuation of the project, with multiple uncertainty factors. Besides considering a stochastic demand, the effect of uncertainty in the investment’s expenditure and over the benefit per user is incorporated in a model with three stochastic variables. The modelling approach used is based on the differential utility provided to railway users by the HSR service.info:eu-repo/semantics/publishedVersio

    Experience with a middleware infrastructure for service oriented financial applications

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    Financial institutions, acting as financial intermediaries, need to handle numerous information sources and feed them to multiple processing, storage, and display services. This requires filtering and routing, but these feeds are usually provided in custom formats and protocols that are not the best fit for further processing. Moreover, the sheer volume of information and stringent timeliness and reliability requirements make this a substantial task. In this paper, i) we characterize one of these information feeds (the Exchange Data Publisher feed from the NYSE Euronext European Cash Markets) and ii) we present and evaluate a dissemination system for this particular feeder based on commodity hardware and open-source message-oriented middleware (Apache Qpid). This allows us to assess the feasibility of this approach and to point out the main challenges to be overcome.(undefined

    Identification and validation of microsatellite markers in strawberry tree (Arbutusunedo L.)

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    Strawberry tree (Arbutus unedo L.), an evergreen shrub/small tree of the family Ericaceae, is a main constituent of the Mediterranean basin flora; although it is also found in southwestern Prance, Macaronesia, and Ireland. The small fruits are edible but mostly used for preparation of preserves and jams, and for liquors such as the Portuguese traditional "aguardente de medronho". Traditionally cultivated by small farmers, often in consociation with Quercus sp., strawberry tree is presently emerging as a new important fruit crop cultivated in large orchards by modern export-oriented enterprises. This change of paradigm requires a growing role of plant breeding, upstream of the production process. Genomic tools for this species are mostly limited to the chloroplast genome sequence and to genomic data described in this work. In order to identify strawberry tree microsatellite (SSR) loci we performed partial genome next-generation sequencing using the Ion Torrent technology. The sequenced similar to 24.6M nucleotides resulted in the identification of 1185 microsatellite markers mostly constituted by dinucleotide motifs. The relative amount of microsatellite dinucleotide motifs (AG/CT - 71.7%, AC/GT - 20.5%, AT/AT - 2.9%, and CG/CG - 0.3%) is similar to the one observed in other Ericaceae species. Among a tested sample of 40 SSR primer pairs, 20 amplified well-defined PCR products, 12 (30%) were validated as polymorphic. Used in our collaborative project for molecular identification of selected and improved clones, the identified SSR loci constitute a strong tool for a large panoply of applied and fundamental studies of this emerging fruit crop.Pluriannual Funding Program of the Portuguese National Foundation for Science and Technologyinfo:eu-repo/semantics/publishedVersio

    Using the Smith Chart in an E-Learning Approach

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    Sand mining in Calhetona beach (Santiago Island, Cape Verde): causes, processes and consequences

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    A extracção clandestina de areia, nas faixas costeiras e nos leitos das ribeiras, tem sido prática de muitos agregados familiares cabo-verdianos. Nas últimas décadas, a praia de Calhetona (Ilha de Santiago) foi um dos muitos locais que sofreram degradação ambiental significativa, devido à realização desta actividade sem quaisquer planos de extracção e de posterior recuperação das áreas degradadas. Este trabalho, através da conjugação de recolha de dados por inquérito, observação directa e pesquisa documental e bibliográfica, teve como objectivos a caracterização da comunidade (que habita no bairro de Ponta Calhetona) que se dedica à extracção de areia na praia de Calhetona, a descrição da dinâmica da actividade extractiva, a avaliação da percepção que a comunidade tem relativamente às consequências da sua actividade e a descrição do impacte ambiental resultante da extracção de areia. Da análise dos inquéritos, efectuados em Fevereiro de 2012, a 25 chefes de agregados familiares que efectuam a extracção de areia na praia de Calhetona, constata-se que estes são maioritariamente mulheres, predominantemente com idade compreendida entre os 40 e os 59 anos, domésticas, com baixa escolaridade, com famílias numerosas e/ou alargadas a seu cargo e dedicando-se à extração de areia à mais de 10 anos. Os inquiridos, face à situação de vulnerabilidade económica, à falta de emprego e à grande procura de areia para a construção civil, vêem nesta actividade uma fonte de rendimento. Contudo, o proveito obtido desta actividade difícil e potencialmente perigosa é reduzido. Quem efectivamente beneficia são os camionistas que compram a areia a quem procede à extracção e a vendem ao consumidor final pelo dobro do preço. Os inquiridos demonstram uma consciência generalizada dos diversos impactes ambientais negativos resultantes da sua actividade, mas alegam que a extracção de areia é uma das poucas alternativas existentes para providenciar o sustento dos seus agregados familiares. Com base na comparação do estado actual da praia de Calhetona com relatos de habitantes locais, relativos às características da mesma no passado, verifica-se que nos últimos 40-50 anos, desde que se iniciou a intensa extracção de areia nesta praia, o seu aspecto físico se degradou claramente. Essa degradação caracteriza-se principalmente pelo recuo da linha de costa, pela quase ausência de areia e pela salinização dos solos localizados nas proximidades da praia, para além dos consequentes impactes negativos sobre a desova das tartarugas e o turismo balnear.Sand is a very important raw material for construction industry. Worldwide, it has been widely used in the urban and industrial expansion process, creating jobs, generating capital and thus contributing to the development of society. However, its over-exploitation is also cause of many environmental problems identified all over the world. In Cape Verde archipelago ilegal sand mining has been intensively carried out in coastal areas and in stream beds without extraction plans or rehabilitation of degraded areas. In the archipelago sand exploitation was insignificant until the early 1980s, because this material was used only in the lining of outer (stone) walls. Since then, there was a huge increase in construction of infrastructures and public and private buildings due to: the migration of rural populations to the cities; the remittances; the improvement of living conditions; the evolution of the building techniques; and the liberalization of construction materials. The use of sand, gravel and cement (concrete blocks) quickly replaced the use of stone. The use of sand in construction became so widespread that the consequences of its use/exploitation quickly became quite evident in the archipelago. The environmental impact of this mining activity has become so serious that in 1997, the Cape Verdean government was forced to introduce legislation prohibiting sand exploitation in the dunes, beaches and inland waters, with the exception of duly authorized cases. However, despite the existing legislation and inspection, the environmental problems resulting from this activity are still present, since there are many people dedicated to illegal sand mining. The economic vulnerability experienced by the Cape Verdean families has contributed to the ineffectiveness of environmental legislation. A large part of the population lives below the poverty line, so the exploitation of natural resources has been used in an abusive manner to ensure the survival of populations in need. In parallel, the high demand for sand and gravel has favoured illegal exploitation on the beaches and creeks of the archipelago. This illegal activity is traditionaly dominated by women heads of poor households without alternative employment or low ability to generate self-employment. Santiago Island, where resides more than half of the archipelago's population, is by far the largest sand consumer market. This, coupled with the shortage of this mineral resource in the archipelago and the difficult living conditions of the population, puts the mining areas of the islands under enormous pressure. In recent decades, Calhetona Beach (Santiago Island) was one of the many places that suffered significant degradation due to this activity. Thus, having gathered data through the combination of enquiry, direct observation and document analysis, this work intended to: characterize the community (living in Ponta Calhetona neighborhood) dedicated to sand mining in Calhetona Beach; describe the dynamics of the mining activity; assess the perception of the community regarding the consequences of its activity; and describe the environmental impacts resulting from sand mining. The analysis of the survey of 25 heads of households that extract sand from Calhetona Beach shows that these are mostly women, mostly between 40 and 59 years old, unemployed, with low education levels, with dependent numerous and/or extended families and mostly extracting sand for over 10 years. Sand extraction on Calhetona Beach is not dependent on the tide, because, contrary to what happens in other beaches on the island, it does not take place in the water, but is strongly conditioned by the authorithies surveillance. During the night is more difficult to be seen by the inspection agents and easier to escape them. The extraction is commonly made using buckets and padbles and the transportation to the storage location is commonly done in tubs and bags. Because it is a clandestine activity, storage is done in places away from the site of extraction in order to avoid problems with the authorities. On Calhetona Beach, as a result of the authorities pressure, the sand is predominantly sold to the bag. Even in the cases the sand is sold to the carload, the sand is still transported to the place of deliverance in bags to complete the carload. Considering that a Toyota Dyna 280 can carry 4500 to 5000 kg and a bag carries only about 50 kg, it takes 90 to 100 bags to complete a carload. The selling price of a sand bag is about 30000to40000 to 40000 (circa 3 to 4€), whereas a carload (Toyota Dyna 280) is about 7,00000to8,00000 to 8,00000 (circa 64 to 73€). The sand is sold mainly to truckers, construction contractors and nearby residents. The truckers (men) are the ones who actually benefit from this activity, buying the sand to the miners and sell it to the end consumer for about 15,000$00 (circa 135€). The delivery of sand to buyers is always carried out at night and early morning to avoid the fines and the seizure of the sand (and the vehicle) by the authorities. The preference for Toyota Dyna 280 is due to the ability of these vehicles to easily move through the alleys of the neighborhood and to escape the authorities because of the speeds that can reach with its turbo engine. The respondents demonstrate a widespread awareness of the various negative economic and environmental impacts resulting from their activity. But they claim that sand mining is one of the few existing alternatives to provide the sustenance of their households. The comparison of the past and the current conditions of Calhetona beach shows that in the last 40-50 years, since the beginning of intensive sand mining in this beach, there was a clear environmental degradation depicted by the retreat of the shoreline, the near absence of sand or the predominence of gravel, the presence of a permanent saltwater pond parallel to the seashore, the salinization of nearby soils, and the consequent negative impacts on turtle nesting, beach tourism and agriculture

    Towards delay-aware container-based Service Function Chaining in Fog Computing

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    Recently, the fifth-generation mobile network (5G) is getting significant attention. Empowered by Network Function Virtualization (NFV), 5G networks aim to support diverse services coming from different business verticals (e.g. Smart Cities, Automotive, etc). To fully leverage on NFV, services must be connected in a specific order forming a Service Function Chain (SFC). SFCs allow mobile operators to benefit from the high flexibility and low operational costs introduced by network softwarization. Additionally, Cloud computing is evolving towards a distributed paradigm called Fog Computing, which aims to provide a distributed cloud infrastructure by placing computational resources close to end-users. However, most SFC research only focuses on Multi-access Edge Computing (MEC) use cases where mobile operators aim to deploy services close to end-users. Bi-directional communication between Edges and Cloud are not considered in MEC, which in contrast is highly important in a Fog environment as in distributed anomaly detection services. Therefore, in this paper, we propose an SFC controller to optimize the placement of service chains in Fog environments, specifically tailored for Smart City use cases. Our approach has been validated on the Kubernetes platform, an open-source orchestrator for the automatic deployment of micro-services. Our SFC controller has been implemented as an extension to the scheduling features available in Kubernetes, enabling the efficient provisioning of container-based SFCs while optimizing resource allocation and reducing the end-to-end (E2E) latency. Results show that the proposed approach can lower the network latency up to 18% for the studied use case while conserving bandwidth when compared to the default scheduling mechanism
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