Forwarding and security in vehicular networks

The growing research in vehicular network solutions provided the rise of interaction in these highly dynamic environments in the market. The developed architectures do not usually focus, however, in security aspects. Common security strategies designed for the Internet require IP. Since nodes' addresses in a vehicular network are too dynamic, such solutions would require cumbersome negotiations, which would make them unsuitable to these environments. The objective of this dissertation is to develop, and test a scalable, lightweight, layer 3 security protocol for vehicular networks, in which nodes of the network are able to set up long-term security associations with a Home Network, avoiding session renegotiations due to lack of connectivity and reduce the protocol stacking. This protocol allows to provide security independent of the nodes (vehicles) position, of its addressing and of the established path to access the Internet, allowing the mobility of vehicles and of its active sessions seamlessly without communication failures.

Hybrid materials for biomedical applications

The increased longevity of humans and the demand for a better quality of life have led to a continuous search for new implant materials. Scientific development coupled with a growing multidisciplinarity between materials science and life sciences has given rise to new approaches such as regenerative medicine and tissue engineering. The search for a material with mechanical properties close to those of human bone produced a new family of hybrid materials that take advantage of the synergy between inorganic silica (SiO4) domains, based on sol-gel bioactive glass compositions, and organic polydimethylsiloxane, PDMS ((CH3)2.SiO2)n, domains. Several studies have shown that hybrid materials based on the system PDMS-SiO2 constitute a promising group of biomaterials with several potential applications from bone tissue regeneration to brain tissue recovery, passing by bioactive coatings and drug delivery systems. The objective of the present work was to prepare hybrid materials for biomedical applications based on the PDMS-SiO2 system and to achieve a better understanding of the relationship among the sol-gel processing conditions, the chemical structures, the microstructure and the macroscopic properties. For that, different characterization techniques were used: Fourier transform infrared spectrometry, liquid and solid state nuclear magnetic resonance techniques, X-ray diffraction, small-angle X-ray scattering, smallangle neutron scattering, surface area analysis by Brunauer–Emmett–Teller method, scanning electron microscopy and transmission electron microscopy. Surface roughness and wettability were analyzed by 3D optical profilometry and by contact angle measurements respectively. Bioactivity was evaluated in vitro by immersion of the materials in Kokubos’s simulated body fluid and posterior surface analysis by different techniques as well as supernatant liquid analysis by inductively coupled plasma spectroscopy. Biocompatibility was assessed using MG63 osteoblastic cells. PDMS-SiO2-CaO materials were first prepared using nitrate as a calcium source. To avoid the presence of nitrate residues in the final product due to its potential toxicity, a heat-treatment step (above 400 °C) is required. In order to enhance the thermal stability of the materials subjected to high temperatures titanium was added to the hybrid system, and a material containing calcium, with no traces of nitrate and the preservation of a significant amount of methyl groups was successfully obtained. The difficulty in eliminating all nitrates from bulk PDMS-SiO2-CaO samples obtained by sol-gel synthesis and subsequent heat-treatment created a new goal which was the search for alternative sources of calcium. New calcium sources were evaluated in order to substitute the nitrate and calcium acetate was chosen due to its good solubility in water. Preparation solgel protocols were tested and homogeneous monolithic samples were obtained. Besides their ability to improve the bioactivity, titanium and zirconium influence the structural and microstructural features of the SiO2-TiO2 and SiO2-ZrO2 binary systems, and also of the PDMS-TiO2 and PDMS-ZrO2 systems. Detailed studies with different sol-gel conditions allowed the understanding of the roles of titanium and zirconium as additives in the PDMS-SiO2 system. It was concluded that titanium and zirconium influence the kinetics of the sol-gel process due to their different alkoxide reactivity leading to hybrid xerogels with dissimilar characteristics and morphologies. Titanium isopropoxide, less reactive than zirconium propoxide, was chosen as source of titanium, used as an additive to the system PDMS-SiO2-CaO. Two different sol-gel preparation routes were followed, using the same base composition and calcium acetate as calcium source. Different microstructures with high hydrophobicit were obtained and both proved to be biocompatible after tested with MG63 osteoblastic cells. Finally, the role of strontium (typically known in bioglasses to promote bone formation and reduce bone resorption) was studied in the PDMS-SiO2-CaOTiO2 hybrid system. A biocompatible material, tested with MG63 osteoblastic cells, was obtained with the ability to release strontium within the values reported as suitable for bone tissue regeneration.

Mobilidade sustentável : interação entre veículos motorizados e utentes vulneráveis da via pública

O automóvel tem sido nas últimas décadas o principal meio de transporte para a realização de deslocações diárias. Este é um panorama tanto a nível Nacional como Europeu e deve-se ao crescimento económico e aos investimentos centrados em infraestruturas rodoviárias. A organização das atividades e o planeamento nos meios urbanos está, muitas vezes, projetada em função do automóvel e pouco preparado para outras formas de mobilidade, nomeadamente para peões e ciclistas. Existe uma necessidade de mudança deste panorama e a necessidade de uma sociedade que privilegie os modos de transporte suave. No entanto, surge a necessidade de garantir a segurança dos utentes mais vulneráveis da via pública. Esta dissertação de Mestrado tem como principal objetivo analisar de que forma a sinistralidade viária para peões e ciclistas tem evoluído nas freguesias abrangidas pela atividade da Polícia de Segurança Pública (PSP) de Aveiro e quais as principais dificuldades que estes enfrentam nas suas deslocações diárias. Para alcançar este objetivo foram analisados dados de sinistralidade viária fornecidos pela PSP do comando distrital de Aveiro que envolviam a interação de veículos motorizados e utentes vulneráveis da via pública (peões ou ciclistas). Numa segunda fase foi elaborado um inquérito, com o objetivo de perceber as principais dificuldades encontradas pelos utentes da Universidade que privilegiam os modos de deslocação suave nas suas viagens diárias. Este estudo revelou que para a área em estudo, no concelho de Aveiro, o número de acidentes que envolvem a interação de veículos motorizados com utentes vulneráveis da via pública aumentou 5% de 2012 a 2013 e 4% de 2013 a 2014. Os utentes com idades superiores a 55 anos revelaram-se os mais vulneráveis, não só em termos de número de ocorrências mas também na gravidade de lesões, representando 50% de mortes e feridos graves, Em termos de atropelamento de peões existe uma forte tendência para peões do sexo feminino (73%), em oposição ao perfil do condutor atropelante onde 69% são do sexo masculino Em relação a acidentes envolvendo ciclistas, 68% dos lesados são do sexo masculino. Uma possível explicação poderá consistir numa maior utilização de bicicletas por parte dos mesmos, como foi comprovado na amostra recolhida no inquérito, mas não existem mais estatísticas em Aveiro sobre a distribuição por género dos utilizadores de bicicleta. Do inquérito efetuado conclui-se que os principais problemas encontrados pelos utentes inquiridos são, à semelhança de peões e ciclistas, a falta de sensibilização dos automobilistas e as condições meteorológicas. Em terceiro lugar encontra-se, para os peões, o aumento do risco de atos de vandalismo e assaltos e, para os ciclistas, a falta de vias dedicadas. Por outro lado, as principais motivações são, tanto para peões como para ciclistas, o custo reduzido ou nulo e a facilidade de locomoção.

Vaness: DNS for nomadic users in vehicular networks

Vehicular networks, also known as VANETs, are an ad-hoc network formed by vehicles and road-side units. Nowadays they have been attracting big interest both from researchers as from the automotive industry. With the upcoming of automotive specific operating systems and self-driving cars, the use of applications on vehicles and the integration with common mobile devices is becoming a big part of VANETs. Although many advances have been made on this field, there is still a big discrepancy between the communication layer services provided by VANETs and the user level services, namely those accessible through mobile applications on other networks and technologies. Users and developers are accustomed to user-to-user or user-tobusiness communication without explicit concerns related with the available communication transport layer. Such is not possible in VANETs since people may use more than one vehicle. However, to send a message to a specific user in these networks, there is a need to know the ID of the vehicle where the user is, meaning that there is a lack of services that map each individual user to VANETs endpoint (vehicle identification). This dissertation work proposes VANESS, a naming service as a resource to support user-to-user communication within a heterogeneous scenario comprising typical ISP scenario and VANETs focused on mobile devices. The proposed system is able to map the user to an end point either locally (i.e. there is not internet connection at all), online (i.e. system is not in a vehicular network but has direct internet connection) and using a gateway (i.e. the system is in a vehicular network where some of the nodes have internet access and will act as a gateway). VANESS was fully implemented on android OS with results proving his viability, and partially on iOS showing its multiplatform capabilities.