774 resultados para Key Management Protocol


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Many organisations need to extract useful information from huge amounts of movement data. One example is found in maritime transportation, where the automated identification of a diverse range of traffic routes is a key management issue for improving the maintenance of ports and ocean routes, and accelerating ship traffic. This paper addresses, in a first stage, the research challenge of developing an approach for the automated identification of traffic routes based on clustering motion vectors rather than reconstructed trajectories. The immediate benefit of the proposed approach is to avoid the reconstruction of trajectories in terms of their geometric shape of the path, their position in space, their life span, and changes of speed, direction and other attributes over time. For clustering the moving objects, an adapted version of the Shared Nearest Neighbour algorithm is used. The motion vectors, with a position and a direction, are analysed in order to identify clusters of vectors that are moving towards the same direction. These clusters represent traffic routes and the preliminary results have shown to be promising for the automated identification of traffic routes with different shapes and densities, as well as for handling noise data.

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A massificação da utilização das tecnologias de informação e da Internet para os mais variados fins, e nas mais diversas áreas, criou problemas de gestão das infra-estruturas de informática, ímpares até ao momento. A gestão de redes informáticas converteu-se num factor vital para uma rede a operar de forma eficiente, produtiva e lucrativa. No entanto, a maioria dos sistemas são baseados no Simple Network Management Protocol (SNMP), assente no modelo cliente-servidor e com um paradigma centralizado. Desta forma subsiste sempre um servidor central que colecta e analisa dados provenientes dos diferentes elementos dispersos pela rede. Sendo que os dados de gestão estão armazenados em bases de dados de gestão ou Management Information Bases (MIB’s) localizadas nos diversos elementos da rede. O actual modelo de gestão baseado no SNMP não tem conseguido dar a resposta exigida. Pelo que, existe a necessidade de se estudar e utilizar novos paradigmas de maneira a que se possa encontrar uma nova abordagem capaz de aumentar a fiabilidade e a performance da gestão de redes. Neste trabalho pretende-se discutir os problemas existentes na abordagem tradicional de gestão de redes, procurando demonstrar a utilidade e as vantagens da utilização de uma abordagem baseada em Agentes móveis. Paralelamente, propõe-se uma arquitectura baseada em Agentes móveis para um sistema de gestão a utilizar num caso real.

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Secure group communication is a paradigm that primarily designates one-to-many communication security. The proposed works relevant to secure group communication have predominantly considered the whole network as being a single group managed by a central powerful node capable of supporting heavy communication, computation and storage cost. However, a typical Wireless Sensor Network (WSN) may contain several groups, and each one is maintained by a sensor node (the group controller) with constrained resources. Moreover, the previously proposed schemes require a multicast routing support to deliver the rekeying messages. Nevertheless, multicast routing can incur heavy storage and communication overheads in the case of a wireless sensor network. Due to these two major limitations, we have reckoned it necessary to propose a new secure group communication with a lightweight rekeying process. Our proposal overcomes the two limitations mentioned above, and can be applied to a homogeneous WSN with resource-constrained nodes with no need for a multicast routing support. Actually, the analysis and simulation results have clearly demonstrated that our scheme outperforms the previous well-known solutions.

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A gestão das redes informáticas converteu-se num fator vital para as redes operarem de forma eficiente, produtiva e lucrativa. A gestão envolve a monitorização e o controlo dos sistemas para que estes funcionem como o pretendido. Ações de configuração, monitorização e reconfiguração dos componentes, são essenciais para melhorar o desempenho, diminuir o tempo de inatividade, melhor a segurança e efetuar contabilização. A maioria das aplicações de gestão de Redes assenta no paradigma centralizado cliente-servidor, onde um servidor central coleta e analisa dados provenientes dos diferentes elementos dispersos pela rede. Esses dados de gestão estão armazenados em bases de dados de gestão localizadas nos diversos elementos da rede. No entanto, este paradigma não tem conseguido dar resposta às exigências das redes atuais. Surge assim a necessidade de utilizar novos paradigmas para a gestão das redes. Uma alternativa baseada no paradigma dos agentes móveis já foi estudada, proposta e desenvolvida para a gestão da rede do GECAD-ISEP. Neste trabalho pretende-se propor e adicionar novas capacidades aos agentes móveis existentes, assim como novos agentes. Com vista à validação da solução proposta recorre-se à utilização de um simulador de redes.

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Aquest projecte presenta, en primer lloc, un estudi dels protocols de generació de claus criptogràfiques i autoritats de certificació distribuïdes més destacables desenvolupades fins a l'actualitat. Posteriorment, implementem un protocol, que toleri les errades, de generació distribuïda de claus RSA sense servidor de confiança, orientat a xarxes ad-hoc. El protocol necessita la participació conjunta de n nodes per generar un mòdul RSA (N = pq), un exponent d'encriptació públic i les particions de l'exponent privat d, seguint un esquema llindar (t, n).

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OBJECTIVES: This systematic review aims to assess the risks (both thromboembolic and bleeding) of an oral anticoagulation therapy (OAT) patient undergoing implant therapy and to provide a management protocol to patients under OAT undergoing implant therapy. MATERIAL AND METHODS: Medline, Cochrane Data Base of Systematic Reviews, the Cochrane Central Register of Controlled Trials and EMBASE (from 1980 to December 2008) were searched for English-language articles published between 1966 and 2008. This search was completed by a hand research accessing the references cited in all identified publications. RESULTS: Nineteen studies were identified reporting outcomes after oral surgery procedures (mostly dental extractions in patients on OAT following different management protocols and haemostatic therapies). Five studies were randomized-controlled trials (RCTs), 11 were controlled clinical trials (CCTs) and three were prospective case series. The OAT management strategies as well as the protocols during and after surgery were different. This heterogeneity prevented any possible data aggregation and synthesis. The results from these studies are very homogeneous, reporting minor bleeding in very few patients, without a significant difference between the OAT patients who continue with the vitamin K antagonists vs. the patients who stopped this medication before surgery. These post-operative bleeding events were controlled only with local haemostatic measures: tranexamic acid mouthwashes, gelatine sponges and cellulose gauzes's application were effective. Post-operative bleeding did not correlate with the international normalised ratio (INR) status. In none of the studies was a thromboembolic event reported. CONCLUSIONS: OAT patients (INR 2-4) who do not discontinue the AC medication do not have a significantly higher risk of post-operative bleeding than non-OAT patients and they also do not have a higher risk of post-operative bleeding than OAT patients who discontinue the medication. In patients with OAT (INR 2-4) without discontinuation, topical haemostatic agents were effective in preventing post-operative bleeding. OAT discontinuation is not recommended for minor oral surgery, such as single tooth extraction or implant placement, provided that this does not involve autogenous bone grafts, extensive flaps or osteotomy preparations extending outside the bony envelope. Evidence does not support that dental implant placement in patients on OAT is contraindicated.

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El despliegue de un esquema de confianza es fundamental para poder desarrollar servicios de seguridad que permitan administrar y operar una red. Sin embargo, las soluciones empleadas en las redes tradicionales no se adaptan a un entorno ad hoc debido a la naturaleza dinámica y sin infraestructura de estas redes. En el presente trabajo se propone un esquema de confianza práctico y eficiente basado en una infraestructura de clave pública distribuida, umbral y jerárquica, que no requiere sincronización temporal entre todos los nodos de la red. La autorización de usuarios en el sistema se hace a través de certificados de corta duración que eliminan la necesidad de mantener la publicación y diseminación de unas listas de revocación. Por otro lado, una entidad externa de confianza permite alargar la reputación de un usuario de la red más allá de la existencia de la propia red.

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This study focuses on corporate social responsibility (or CSR)as the latest dimension to emerge in the corporate responsibility and sustainability agenda, which in the recent past has rapidly risen to the top of the list of concerns for civil societies worldwide. Despite the continuing debates and discussions about the scope, benefits, and impacts of CSR to business and community in various sectors, levels, and types of society, many companies have moved forward to confront the opportunities and challenges of CSR. Thus, this study is about those proactive companies with a focus on the importance of CSR and its management inside and outside the company. It is an exploration and learning from the experience of Finnish companies, as well as other actors interested or involved in shaping the course of CSR, locally and globally. It also looks closely at how national culture affects the views, thinking, and management of CSR in a welfare state. This dissertation primarily draws on the analyses of information collected from a series of qualitative interviews and the existing literature in the area. This is complemented by an analysis of written and published documents on CSR from various sources. The results of the study give insightful information and detailed descriptions of a roadmap useful in learning and understanding CSR in Finnish companies. Despite the varying conceptual connotations, essential roadmap indicators point to the importance of framing CSR within the corporate responsibility concept, Finnish development and the welfare state system, globalization, stakeholders, and the pursuit of sustainable development as the main drivers of CSR, the remarkable progress of CSR in companies, and identification of key management areas and practices relevant to CSR. Similarly,the study reveals the importance of culture as essential in understanding and learning CSR. Finnish culture has a positive influence on the views, thinking, and management practices of CSR issues. Such a positive influence of culture, therefore, makes it easy for business people to discuss and understand CSR, because those CSR issues are already considered common and taken-for-granted by Finns and are implicit in the welfare state provisions. The experience of Finnish companies in implementing CSR policies in the supply chain is a concrete proactive step in advancing the message of CSR, that is, to bring companies and suppliers together to work on improving and strengthening relationships towards socially responsible practices worldwide. Such a forward step to deal with CSR issues in the supply chain reflects the companies' commitments and belief that CSR can be managed with the suppliers and gain positive benefits. Despite the problems and complexities, particularly in the global supply chain, managing CSR for Finnish companies presents new opportunities and challenges that are expected to intensify in the near future. The focus on CSR policy implementation inthe supply chain points to the importance of companies taking initiatives and forging cooperation with suppliers with the aim of addressing and improving CSR questions in the supply chains. The proactive stance of Finnish companies toward CSR is complemented by the active supporting role of important societalactors such as the government and NGOs. These actors carry out various promotional efforts and campaigns, thus bringing CSR into the mainstream of Finnish companies and strengthening the synergistic learning about CSR within the Finnish business and civil circles. The efforts of the government and NGOs to promote CSR are indicative of the importance of multipartite involvement and the emergence of better civil regulations. Likewise, their drive to learn from each other, exchange experiences, and contribute in CSR debates facilitated the evolution of CSRnetworks in the country. The results of this study add to the mounting evidence that CSR, in general, has created a new dimension in managing corporate sustainability. This study provides compelling empirical evidence and some direct quotations about CSR in the Finnish context. This information can be used to learn and gain new useful insights, approaches, and concepts for managing CSR.

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Tässä diplomityössä selvitetään SNMP:n (Simple Network Management Protocol) hallintatietokantojen sisältämiä palvelunlaatutietoja. Tarkastelun kohteena ovat IP:n (Internet Protocol) ja ATM:n (Asynchronous Transfer Mode) hallintatietokannat. Työn teoriaosassa tarkastellaan verkonhallinnan eri osa-alueita, TCP/IP-verkkojen (Transmission Control Protocol) hallintaan tarkoitettua SNMP-protokollaa ja sen eri versioita. Lisäksi käsitellään palvelunlaadun kannalta IP ja ATM-verkkojen erilaisia toteutuksia. Työn kokeellissa osassa arvioidaan eri hallintatietokantojen sisältöä palvelunlaadun kannalta. Työssä todetaan palvelunlaatutietojen puutteellisuus hallintatietokannoissa ja sekä IP:lle että ATM:lle toteutetaan soveltuvat hallintatietokannat.

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Multicast is one method to transfer information in IPv4 based communication. Other methods are unicast and broadcast. Multicast is based on the group concept where data is sent from one point to a group of receivers and this remarkably saves bandwidth. Group members express an interest to receive data by using Internet Group Management Protocol and traffic is received by only those receivers who want it. The most common multicast applications are media streaming applications, surveillance applications and data collection applications. There are many data security methods to protect unicast communication that is the most common transfer method in Internet. Popular data security methods are encryption, authentication, access control and firewalls. The characteristics of multicast such as dynamic membership cause that all these data security mechanisms can not be used to protect multicast traffic. Nowadays the protection of multicast traffic is possible via traffic restrictions where traffic is allowed to propagate only to certain areas. One way to implement this is packet filters. Methods tested in this thesis are MVR, IGMP Filtering and access control lists which worked as supposed. These methods restrict the propagation of multicast but are laborious to configure in a large scale. There are also a few manufacturerspecific products that make possible to encrypt multicast traffic. These separate products are expensive and mainly intended to protect video transmissions via satellite. Investigation of multicast security has taken place for several years and the security methods that will be the results of the investigation are getting ready. An IETF working group called MSEC is standardizing these security methods. The target of this working group is to standardize data security protocols for multicast during 2004.

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Tietoverkkojen valvontajärjestelmiä on nykyään käytössä monissa eri verkkoympäristöissä. Näissä verkoissa käytetään useiden laitevalmistajien tuotteita, joita täytyy pystyä valvomaan. Tähän tarkoitukseen on kehitetty verkonhallintaprotokolla SNMP (Simple Network Management Protocol). Tässä työssä valvontaprotokollaa on tarkoitus soveltaa tietoverkkojen valvontaan. Tämä insinöörityö tehtiin osana Netcontrol Oy:n tuotekehitystä. Työn päätavoitteena oli kehittää toimiva ratkaisu verkonvalvontaan. Työssä tutkittiin myös verkonvalvonnan toteuttamista SNMP-protokollan avulla sekä eri verkonvalvonnan toteutusmalleja. Työn teoriaosuus tehtiin kirjallisuustutkimuksena. Teoriaosuudessa käydään läpi verkonvalvonnan taustoja, SNMP-protokollan eri versioiden ominaisuuksia ja tietokantojen rakennetta. Työn loppuosassa kerrotaan Windows-käyttöjärjestelmän SNMP-ohjelmista sekä avoimen lähdekoodin Net-SNMP-ohjelmasta. Lisäksi käydään läpi näiden ohjelmien käyttöönotto. Lopussa kerrotaan myös testijärjestelmän tuloksista yleisluontoisesti. Työ osoittaa, että SNMP:n avulla pystytään suorittamaan kattavaa verkonvalvontaa. SNMP:n toiminnallisuus saadaan aikaan työssä esitetyillä ohjelmistoilla eri tietoverkon laitteisiin. Laitteiden valvontaa pystytään suorittamaan SNMP-hallintaohjelmalla. Näiden ohjelmistojen avulla saadaan aikaan toimiva päästä päähän -ratkaisu verkonvalvontaan. Tarkemmat kuvaukset testijärjestelmistä ja kehitysmahdollisuuksista on sisällytetty liitteeseen, joka on luottamuksellinen.

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The main objective of this study was to examine the pricing of customized industrial products in international markets, and to understand what pricing decision making consists of. Another purpose of the study was to identify the main factors that affect the pricing decisions of industrial companies, as well as the different pricing strategies industrial companies may choose when pricing customized products. The research was conducted as a qualitative single case study, and a Finnish industrial company specializing in indoor environment solutions, Halton Marine Oy, was used as the case company in the study. The primary data was collected through semi-structured theme interviews with the key management personnel of the company, and the results were discussed and analyzed in the light of the existing literature. The results of this study indicate that the pricing of customized industrial products consists of several dimensions, and is influenced by a large variety of factors that are both internal and external to the firm. In addition, it was found that the choice of a pricing strategy is largely dependent on the chosen segment, the product category, and the stage in the product life cycle. The results also suggest that customizing companies should consider using the value-based pricing orientation, since customization is closely linked to customer value.

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Dans ce mémoire, nous proposons des protocoles cryptographiques d'échange de clef, de mise en gage, et de transfert équivoque. Un premier protocole de transfert équivoque, primitive cryptographique universelle pour le calcul multi-parties, s'inspire du protocole d'échange de clef par puzzle de Merkle, et améliore les résultats existants. Puis, nous montrons qu'il est possible de construire ces mêmes primitives cryptographiques sans l'hypothèse des fonctions à sens unique, mais avec le problème 3SUM. Ce problème simple ---dans une liste de n entiers, en trouver trois dont la somme a une certaine valeur--- a une borne inférieure conjecturée de Omega(n^2).

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El Trauma Craneoencefálico (TCE) infantil constituye un motivo frecuente de consulta en Urgencias y supone la primera causa de muerte en niños, llegando a ser hasta del 50% en trauma severo. En Colombia se conocen cifras de TCE por algunos estudios descriptivos, pero no existen reportes en Bogotá ni específicamente en TCE severo. Objetivo: Caracterizar el trauma craneoencefálico severo pediátrico en la Unidad de Cuidado intensivo del Hospital de la Misericordia entre los años 2010 y 2013. Materiales y métodos: Un estudio descriptivo retrospectivo fue realizado en el Hospital de la Misericordia mediante revisión de las historias clínicas de los pacientes que ingresaron a la Unidad de Cuidado Intensivo pediátrico con diagnóstico de trauma craneoencefálico severo entre el año 2010 al 2013. Resultados: Se incluyeron 63 pacientes (71,4% hombres) con una edad mediana de 4 años (RIQ 2-8). La mayoría de los traumas fueron originados por caída o accidente de tránsito (79,4%). La principal lesión fue fractura de cráneo (79%). Casi la mitad de los pacientes sufrieron algún tipo de secuela neurológica al egreso (47,1%). La mayoría de los pacientes que murieron (19%) sufrieron choque hipovolémico (83,3%) y presentaron trauma asociado (66,7%). Conclusión: Las características y epidemiología del trauma craneoencefálico en nuestra población muestran claras similitudes con lo reportados en otras series de la literatura mundial y de Colombia, excepto por la mortalidad, que se esperaba más alta al estudiar solo pacientes con TCE severo.

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Grasslands restoration is a key management tool contributing to the long-term maintenance of insect populations, providing functional connectivity and mitigating against extinction debt across landscapes. As knowledge of grassland insect communities is limited, the lag between the initiation of restoration and the ability of these new habitats to contribute to such processes is unclear. Using ten data sets, ranging from 3 to 14 years, we investigate the lag between restoration and the establishment of phytophagous beetle assemblages typical of species rich grasslands. We used traits and ecological characteristics to determine factors limiting beetle colonisation, and also considered how food-web structure changed during restoration. For sites where seed addition of host-plants occurred the success in replicating beetle assemblages increased over time following a negative exponential function. Extrapolation beyond the existing data set tentatively suggested that success would plateau after 20 years, representing a c. 60% increase in assemblage similarity to target grasslands. In the absence of seed addition, similarity to the target grasslands showed no increase over time. Where seed addition was used the connectance of plant-herbivore food webs decreased over time, approaching values typical of species rich grasslands after c. 7 years. This trend was, however, dependent on the inclusion of a single site containing data in excess of 6 years of restoration management. Beetles not capable of flight, those showing high degrees of host-plant specialisation and species feeding on nationally rare host plants take between 1 and 3 years longer to colonise. Successful grassland restoration is underpinned by the establishment of host-plants, although individual species traits compound the effects of poor host-plant establishment to slow colonisation. The use of pro-active grassland restoration to mitigate against future environmental change should account for lag periods in excess of 10 years if the value of these habitats is to be fully realised.