443 research outputs found
Modelling distributed network attacks with constraints
NeMODe is a declarative system for computer network intrusion detection, providing a declarative domain specific language for describing network intrusion signatures which can span several network packets, by stating constraints over network packets, describing relations between several packets in a declarative and expressive way. It provides several back-end detection mechanisms, all based on a constraint programming framework, to perform the detection of the desired signatures.
In this work, we demonstrate how to model and perform the detection of distributed network attacks using each of the detection mechanisms provided by NeMODe, based in Gecode, adaptive search and MiniSat to perform the detection of the specific intrusions. We also use the sliding network traffic window version of the adaptive search back-end detection mechanism to simulate live network traffic and evaluate the performance of the system in conditions near to real life networks
Declarative domain-specific languages and applications to network monitoring
Os Sistemas de Detecção de Intrusões em Redes de Computadores são provavelmente
usados desde que existem redes de computadores. Estes sistemas têm como objectivo
monitorizarem o tráfego de rede, procurando anomalias, comportamentos indesejáveis
ou vestígios de ataques conhecidos, por forma a manter utilizadores, dados, máquinas
e serviços seguros, garantindo que as redes de computadores são locais de trabalho
seguros.
Neste trabalho foi desenvolvido um Sistema de Detecção de Intrusões em Redes de
Computadores, chamado NeMODe (NEtwork MOnitoring DEclarative approach), que
fornece mecanismos de detecção baseados em Programação por Restrições, bem como
uma Linguagem Específica de Domínio criada para modelar ataques específicos, usando
para isso metodologias de programação declarativa, permitindo relacionar vários
pacotes de rede e procurar intrusões que se propagam por vários pacotes e ao longo do
tempo.
As principais contribuições do trabalho descrito nesta tese são:
Uma abordagem declarativa aos Sistema de Detecção de Intrusões em Redes
de Computadores, incluindo mecanismos de detecção baseados em Programação
por Restrições, permitindo a detecção de ataques distribuídos ao longo de vários
pacotes e num intervalo de tempo.
Uma Linguagem Específica de Domínio baseada nos conceitos de Programação
por Restrições, usada para descrever os ataques nos quais estamos interessados
em detectar.
Um compilador para a Linguagem Específica de Domínio fornecida pelo sistema
NeMODe, capaz de gerar múltiplos detectores de ataques baseados em Gecode,
Adaptive Search e MiniSat; ### Abstract:
Network Intrusion Detection Systems (NIDSs) are in use probably ever since there
are computer networks, with the purpose of monitoring network traffic looking for
anomalies, undesired behaviors or a trace of known intrusions to keep both users, data,
hosts and services safe, ensuring computer networks are a secure place to work.
In this work, we developed a Network Intrusion Detection System (NIDS) called
NeMODe (NEtwork MOnitoring DEclarative approach), which provides a detection
mechanism based on Constraint Programming (CP) together with a Domain Specific
Language (DSL) crafted to model the specific intrusions using declarative methodologies,
able to relate several network packets and look for intrusions which span several
network packets.
The main contributions of the work described in this thesis are:
A declarative approach to Network Intrusion Detection Systems, including detection
mechanisms based on several Constraint Programming approaches, allowing
the detection of network intrusions which span several network packets and spread
over time.
A Domain Specific Language (DSL) based on Constraint Programming methodologies,
used to describe the network intrusions which we are interested in finding
on the network traffic.
A compiler for the DSL able to generate multiple detection mechanisms based on
Gecode, Adaptive Search and MiniSat
Public Policy for Sustainability and Retail Resilience in Lisbon City Center
International organizations, public authorities and researchers have increasingly been
concerned with urban resilience and sustainability. We focus on the triangle retail, urban resilience
and city sustainability, aiming to uncover how cities have coped with retail challenges to increase
their resilience towards a sustainable path, highlighting the role played by public policy. The case
study asks, is Central Lisbon strongly affected by processes of regeneration, touristification and
gentrification, simultaneously with changes in retail. The analysis of planning and other policy
documents complemented by fieldwork evidence shows a close link between public initiatives and
private entrepreneurship and their impacts in the vitality of the core. The text shows that the policy
outlined by local authorities to overcome the decline of the city center and to meet the aims of
sustainability implies urban resilience. The transformation of retail is aligned with that vision and
is supported its achievement, while the commercial fabric suffered an evolution from shopping to
consumption spaces, polarized by culture and entertainment, targeting new consumers and
lifestyles. However, new social and economic challenges arise due to escalating housing prices,
change in retail supply, the excessive dependence of tourism and the danger of losing part of the
city’s identity.info:eu-repo/semantics/publishedVersio
Stereoscopic hand-detection system based on FPGA
Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major de Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 200
Gestão dos resultados: o caso das empresas em insolvência do distrito de Aveiro
A gestão dos resultados assume-se como um tema de destaque para todos os utilizadores da informação financeira, tendo ganho maior destaque após a divulgação de escândalos financeiros a nível internacional.
O presente trabalho tem como principal objetivo analisar se as empresas insolventes do distrito de Aveiro, empreendem práticas de gestão dos resultados.
A literatura relativa às práticas de gestão dos resultados por empresas que enfrentam problemas financeiros, sugere que estas empresas gerem mais resultados do que as empresas que não enfrentam tais dificuldades, fazendo-o em maior vultuosidade nos anos anteriores ao anúncio do estado de insolvência/falência e ainda, que no ano anterior ao anúncio de insolvência/falência, existe uma reversão dos efeitos da gestão praticada anteriormente. Assim, através de uma metodologia baseada numa amostra de controlo e na análise de rácios, propusemo-nos a testar se as evidências recolhidas da literatura se verificavam nas empresas com problemas financeiros do distrito de Aveiro.
A evidência permitiu confirmar que as empresas insolventes do distrito de Aveiro gerem mais os resultados do que as empresas que não enfrentam tais problemas e que o fazem nos períodos anteriores ao anúncio do estado de insolvência, particularmente dois anos antes.
As conclusões obtidas patenteiam um contributo para a comunidade científica e para todos os utilizadores da informação financeira, em particular as instituições financeiras. As principais limitações estão relacionadas com a reduzida dimensão da amostra e o diminuto número de anos em análise que, no entanto, poderão vir a tornar-se pistas para eventuais investigações futuras.The earnings management assumed as a prominent topic for all users of financial information, having gained greater highlight after the financial international scandals.
This main objective of this dissertation is to analyse if insolvent companies in the district of Aveiro undertake earnings management practices.
The literature related with earnings management by distressed firms suggests that these firms engage more in earnings management practices than non-distressed firms, especially in the years preceding the insolvency/bankruptcy announcement, furthermore, it demonstrates the reversal of the effects of the previous management in the year preceding the insolvency/bankruptcy. Thus, through a methodology based on a control sample and ratios analysis, we proposed to test if the evidence collected from literature was verified in Aveiro’s district distressed firms.
The evidence gathered confirms that the referred companies are more involved in managing earnings than non-distressed firms, this is seen in the periods prior to the insolvency announcement, particularly in the preceding two years.
The obtained conclusions represent a contribution to the scientific community and to all users of financial information, especially financial institutions, not obliterating the limitations related to the small sample size and the restricted number of years under analysis, which can however become clues to possible future investigations.Mestrado em Finança
An interactive web-based tool for breast reduction surgery simulation
In this work, we present a 3D web-based interactive tool for numerical modeling and simulation approach to breast reduction surgery simulation, to assist surgeons in planning all aspects related to breast reduction surgery before the actual procedure takes place, thereby avoiding unnecessary risks. In particular, it allows the modeling of the initial breast geometry, the definition of all aspects related to the surgery and the visualization of the post-surgery breast shape in a realistic environment.This work was supported by FCT – Fundação para a Ciência e a Tecnologia, through the project EXPL/MAT-NAN/0606/20132. The researchers also acknowledge LISP – Laboratory of Informatics, Systems and Parallelism and the Computer Science Department of Universidade de ´Evora for providing the conditions to accomplish the work described herein
NILC_USP: aspect extraction using semantic labels
This paper details the system NILC USP that participated in the Semeval 2014: Aspect Based Sentiment Analysis task. This system uses a Conditional Random Field (CRF) algorithm for extracting the aspects mentioned in the text. Our work added semantic labels into a basic feature set for measuring the efficiency of those for aspect extraction. We used the semantic roles and the highest verb frame as features for the machine learning. Overall, our results demonstrated that the system could not improve with the use of this semantic information, but its precision was increased.FAPES
Pastor.i: a smartphone application to facilitate grazing management
Grazing in extensive beef farming systems is often manage in an empirical way based on past
experience and on the visual appreciation of animal behavior and forage potential. Records of
entrances and exits of the animals in the paddocks are rare. However, knowing the occupation
period and the animal density, when coupled with biomass defines the grazing pressure. This
knowledge is essential for planning and making informed decisions, that influence the profitability
of the farm. Moreover, adequate grazing pressure is crucial for the sustainability of many SSPs
where system maintenance is dependent on the balance between grazing pressure and regeneration
or maintenance of trees and shrubs.
Pastor.i is a smartphone application (APP) designed to allow pasture data logging to be very
simple. The application is synchronized with the website and allows the producer to have in his
pocket all the farm, being possible to identify the paddock, calculate the area, record the
movements of the animals and consult the occupation history of the paddock. The application
calculates the actual stocking rate, that can be associated with the location of the animals, obtained
if the animals are using collars with GPS, which allows to know the areas of the paddock that are
most grazed, visualized through heat maps. The information enables localized actions, such as
fertilizing or sowing, to improve areas that are not grazed. The application also allows you to save
photos of the sward. This temporal photographic record provides information on the condition of
trees, the botanical composition and on the tendency of grazing to improve or to worsen coverage.
The APP is available for download, is compatible with Android and is being tested with focus
groups
Iluminação em ambientes fabris: otimização e análise técnica-e-económica
Mestrado em Engenharia Eletrónica e TelecomunicaçõesEsta Dissertação aborda a temática da eficiência energética em sistemas de iluminação fabris. Desde os primórdios da história da humanidade que a iluminação tem representado um papel importante. Não só garante condições de segurança, como começou por ser o intuito primordial das fogueiras pré-históricas, traduzindo-se num elemento de conforto. Atualmente seria impensável conceber as mais diversas atividades económicas e produtivas de um país sem iluminação. Nesse sentido a iluminação representa também um elemento fomentador de produtividade. Não é bem conhecido o impacto que a iluminação tem nos custos operacionais de uma unidade fabril. Principalmente por ser difícil de quantificar separadamente na fatura de eletricidade qual a percentagem correspondente à iluminação. Tipicamente estes custos podem ascender a 20% do orçamento global da autarquia em países desenvolvidos. Por esse motivo, o sector da iluminação tem investido esforço no sentido de promover melhores soluções de iluminação capazes de por um lado de satisfazer os requisitos do espaço a iluminar, e por outro propiciar soluções eficientes do ponto de vista energético. Estas soluções assentam essencialmente no uso de dispositivos mais eficientes (como por exemplo os LED´s ou as lâmpadas compactas fluorescentes) bem como em estratégias de controlo eficientes baseadas em dados sensoriais (como por exemplo deteção de movimento/presença). A combinação destas estratégias permite reduzir os consumos em cerca de 80% quando comparadas com soluções passivas. A empresa Amorim Cork Research Lda. é uma empresa prestadora de serviços ao universo das empresas da Corticeira Amorim, uma das maiores multinacionais de origem portuguesa. Teve origem no negócio da cortiça, em 1870, sendo hoje líder destacada no sector a nível mundial. Dada a dimensão da empresa e a sua subdivisão em várias Unidades Industriais com requisitos individuais, será expectável que a iluminação represente uma parte significativa da fatura de eletricidade. Atualmente, os vários setores encontram-se equipados com soluções de iluminação diferentes, na sua maioria empregando tecnologias passivas, noutros casos com dispositivos eficientes. Há algum interesse em migrar para soluções mais eficientes, em parte suportadas em DALI (com interface de comunicação PLC ou Zigbee).This dissertation addresses the issue of energy efficiency in industrial lighting systems. Since the dawn of human history that the lighting has played an important role. Not only ensures safety, as was originally the primary purpose of prehistoric fires, resulting in a comfort element. Nowadays it would be impossible to conceive the most diverse economic and productive activities of a country without lighting. In this sense the lighting is also a productivity developer element. It is well known the impact that lighting has on operating costs of a plant. Mainly because it is difficult to quantify separately, in the electricity bill, the percentage of lighting. Typically these costs can amount to 20 % of the overall budget of the municipality in developed countries. For this reason, the lighting industry has invested effort to promote better lighting solutions that on the one hand meet the requirements of space to light, and on the other provide efficient solutions from the energy point of view. These solutions are essentially based on the use of more efficient devices (such as the LEDs or compact fluorescent lamps) as well as efficient control strategies based on sensory data (such as motion detection / presence). The combination of these strategies can reduce consumption by 80 % when compared to passive solutions. The Amorim Cork Research Lda. is a company providing services to the population of companies Corticeira Amorim, one of the largest multinationals of Portuguese origin. It originated in the cork business in 1870 and today is the clear leader in the global industry. Given the size of the company and its subdivision in various industrial units with individual requirements, it will be expected that lighting represents a significant part of the electricity bill. Currently, many industries are equipped with different lighting solutions, mostly using passive technologies in other cases with efficient devices. There is some interest in moving to more efficient, partly supported by DALI (with PLC or Zigbee communication interface). Therefore, this work aims to present numbers that can provide a complete answer with respect to effect a change in outdoor lighting
Avian trait-mediated vulnerability to road traffic collisions
Collision with vehicles is an important source of bird mortality, but it is uncertain why some species are killed
more often than others. Focusing on passerines,we testedwhether mortality is associated with bird abundances, and with traits reflecting flight manoeuvrability, habitat, diet, and foraging and social behaviours. We also tested whether the species most vulnerable to road-killing were scarcer near (b500 m) or far (N500–5000 m) from roads. During the breeding seasons of 2009–2011,we surveyed roadkills daily along 50 km of roads, and estimated bird abundances from 74 point counts. After correcting for phylogenetic relatedness, there was strong correlation between roadkill numbers and the abundances of 28 species counted near roads. However, selectivity indices indicated that Blue tit (Parus caeruleus), Blackcap (Sylvia atricapilla) and European goldfinch (Carduelis carduelis) were significantly more road-killed than expected from their abundances, while the inverse was found for seven species. Using phylogenetic generalised estimating equations, we found that selectivity indexes were strongly related to foraging behaviour and habitat type, and weakly so to body size, wing load, diet and social behaviour. The most vulnerable passerines were foliage/bark and swoop foragers, inhabiting woodlands,
with small body size and low wing load. The species most vulnerable to road collisions were not scarcer close to roads. Overall, our study suggests that traits provide a basis to identify the passerine species most vulnerable to road collisions, which may be priority targets for future research on the population-level effects of roadkills
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