198,696 research outputs found
RISK ASSESSMENT OF MALICIOUS ATTACKS AGAINST POWER SYSTEMS
No full textThe new scenarios of malicious attack prompt for their deeper consideration and mainly when critical systems are at stake. In this framework, infrastructural systems, including power systems, represent a possible target due to the huge impact they can have on society. Malicious attacks are different in their nature from other more traditional cause of threats to power system, since they embed a strategic interaction between the attacker and the defender (characteristics that cannot be found in natural events or systemic failures). This difference has not been systematically analyzed by the existent literature. In this respect, new approaches and tools are needed. This paper presents a mixed-strategy game-theory model able to capture the strategic interactions between malicious agents that may be willing to attack power systems and the system operators, with its related bodies, that are in charge of defending them. At the game equilibrium, the different strategies of the two players, in terms of attacking/protecting the critical elements of the systems, can be obtained. The information about the attack probability to various elements can be used to assess the risk associated with each of them, and the efficiency of defense resource allocation is evidenced in terms of the corresponding risk. Reference defense plans related to the online defense action and the defense action with a time delay can be obtained according to their respective various time constraints. Moreover, risk sensitivity to the defense/attack-resource variation is also analyzed. The model is applied to a standard IEEE RTS-96 test system for illustrative purpose and, on the basis of that system, some peculiar aspects of the malicious attacks are pointed ou
Analysis of the Systemic Arrangements of the Built Environment in the Rocinha Favela with the Integrated Modification Methodology’s Diagnostic Phase
No full textWith an extremely high level of complexity, urban structures and the built environment are ever-changing entities, in which transformation is a continuous process. Specific patterns of transformation characterize each specific context, and in different urban systems, similar transformation actions generate different reactions and transformation results. Consequently, to plan for any modification on a formal or informal urban system, it is fundamental to learn about that system’s structure. The IMM methodology focuses on the systemic arrangements of the built environment and proposes holistic procedures to understand the nature of the urban systems as entities based on the unique qualities that each context offers. This chapter presents the results of this specific diagnostic process. In the first phase, the built environment system is broken down into its subsystems, and the relationship between those parts is investigated (horizontal investigation). Later, the synergy between them is outlined and the structural attributes emerging from their symbiosis (vertical investigation) are examined. The synthesis of the subsystems results in structural attributes regarded in IMM as Key Categories. Key Categories are morphology-related emergents that shape and host the dynamic processes of the city. This chapter also provides some information on the challenging data gathering processes that PolimipaRarocinha faced to collect the necessary information to better understand the complex and dynamic nature of the favela from a systemic point of view, offering a comprehensive view of the structural attributes and their complex networks and targeting their measurable factors
From Local Modifications in Selected Pilot Areas to System-Wide Improvements: Transformation Strategies and Retrofitting Procedures According to the Integrated Modification Methodology
No full textIn a complex adaptive system (CAS), minor changes can have a big, nonlinear impact on its performance. Based on that, the PolimiparaRocinha project is used to demonstrate how systemic local actions, integrated with the whole, can produce controlled chain reactions to improve performance at a wider scale. In fact, the presented local transformation actions not only change structurally the intervention zones, but also make tangible improvements in the performance of the whole Rocinha favela, seen as a CAS, even in parts that are not directly touched by the project. After explaining how the transformation strategy is defined on the basis of the Diagnostic phase of the IMM, the improvement actions are applied to some selected pilot areas of the favela. The Retrofitting phase is then presented, showing how it is possible, thanks to numeric indicators, to assess the advancement in the quality of life and environmental performances. The proposed modification reveals indeed the hidden links between the structure and performances of the system thanks to the use of a set of appropriate indicators. The local-based strategic plan adopted by the PolimiparaRocinha project, coordinating minimal and systemic modifications to improve the performances of the whole system, can then be replicated to other parts of the Rocinha favela and in other informal contexts, with the final goal of integrating them with the rest of their cities
The Rocinha Favela as a Paradigmatic Case Study of Informal Settlements in Large Cities: Current Situation and Past Slum-Upgrading Programmes
No full textLocated between two of the wealthiest neighbourhoods of Rio de Janeiro, on a surface of less than 2 km2, the Rocinha favela is considered the largest single slum in Brazil, with an unofficial population between 150,000 and 200,000 inhabitants. Its privileged position, dimension and characteristics, compared to the other circa 1000 favelas of Rio, make Rocinha a paradigmatic case of the socio-economic and environmental contradictions of the Brazilian mega-city, but a significant case study for any slum-upgrading programme. The Brazilian experience with slums upgrading is globally recognized, but it is still fragmented and needs to be improved. An overview of the main slum-upgrading policies and programmes carried out in Rio shows that the lack of appropriate participatory programmes and systemic approaches can hinder successful solutions
Odd type DCT/DST for video coding: Relationships and low-complexity implementations
No full textn this paper, we show a class of relationships which link Discrete Cosine Transforms (DCT) and Discrete Sine Transforms (DST) of types V, VI, VII and VIII, which have been recently considered for inclusion in the future video coding technology. In particular, the proposed relationships allow to compute the DCT-V and the DCT-VIII as functions of the DCT-VI and the DST-VII respectively, plus simple reordering and sign-inversion. Moreover, this paper exploits the proposed relationships and the Winograd factorization of the Discrete Fourier Transform to construct low-complexity factorizations for computing the DCT-V and the DCT-VIII of length 4 and 8. Finally, the proposed signal-flow-graphs have been implemented using an FPGA technology, thus showing reduced hardware utilization with respect to the direct implementation of the matrix-vector multiplication algorithm
An Area-Efficient Variable-Size Fixed-Point DCT Architecture for HEVC Encoding
No full textThis paper proposes an area-efficient fixed-point architecture for the computation of the discrete cosine transform (DCT) of multiple sizes in high efficiency video coding (HEVC). This result is obtained by comparing different DCT factorizations in order to find the most suitable one for implementation in the HEVC encoder. The recursive structure of fast algorithms, which decompose the N-point DCT by means of two N/2-point DCTs, is exploited to execute computations of small-size DCTs in parallel, thus maximizing the hardware reusability while maintaining a constant throughput. The simulation results prove that the proposed solution features reduced rate-distortion losses, with relevant complexity saving compared with the state-of-the-art implementations. Finally, the proposed architecture is exploited to design two families of architectures for the 2D-DCT, namely, folded and full-parallel
- …
