Drought is a natural disaster, which negatively affects millions of people and causes huge economic losses. This thesis investigates agricultural drought in Czechia using machine learning algorithms. The statistical models utilised were Random Forest (RF), Geographical Random Forest (GRF) and Locally Tuned Geographical Random Forest (LT GRF). GRF consists of several RF models trained on a subset of original data. The final prediction is a weighted sum of the prediction of a local and global model. The size of the subset is determined by the tunable parameter. LT GRF addresses spatial variability of subset size and local weight. During the tuning process, optimal parameters are found for every location and then interpolated for unknown regions. The thesis aims to evaluate the performance of each model and compare GRF feature importance output with the global model. The best model features meteorological impor- tances are used to create a drought vulnerability map of Czechia. Produced assessment is compared to existing drought vulnerability projects. 1

Computer security professionals and researchers are investigating proactive techniques for studying network-based attack behavior. Attack modeling is one of these research areas. In this dissertation, we address a novel attack modeling technique called an exploitation graph (e-graph) for representing attack scenarios. The key assumption in this research is that we can use exploitation graphs to represent attack scenarios, and methods involving e-graphs can be applied to provide vulnerability mitigation strategies. The modeling process consists of three primary steps. The first step is the creation of a knowledge base of vulnerability graphs (v-graphs) from known system vulnerabilities. Each v-graph shows necessary preconditions in order to make the vulnerability exploitable, and post-conditions that denote effects after a successful exploitation. A template is used to facilitate the definition of preconditions and post-conditions. The second step involves the association of multiple v-graphs to create an e-graph specific to a system being modeled. Network topology information and security policies (e.g., firewall rules) are encoded during the modeling process. A set of experiments were designed to test the modeling approach in a cluster computing environment consisting of one server node and eight internal computing nodes. Experimental results showed that e-graphs can be used to evaluate vulnerability mitigation solutions, e.g., identifying critical vulnerabilities and evaluating firewall policies. The third step of this process focuses on devising graph-simplification techniques for large e-graphs. Efficient graph-simplification techniques are described based on host and exploitation similarity. The most distinctive feature of these techniques is that, they help to simplify the most complex graph-generation process and do not require excessive memory storage. Experimental results showed that these techniques can not only reduce the size of e-graphs substantially, but also preserve most information needed for useful attack scenario analysis. The usefulness of the e-graph approach is shown in this dissertation. As a general approach for system administrators, the proposed techniques can be used in, but is not limited to, the cluster-computing environment in providing proactive Vulnerability Assessment (VA) strategies.

Doctor of Philosophy / Department of Computing and Information Sciences / Xinming Ou / If you cannot measure it, you cannot improve it. Quantifying security with metrics is important not only because we want to have a scoring system to track our efforts in hardening cyber environments, but also because current labor resources cannot administrate the exponentially enlarged network without a feasible risk prioritization methodology. Unlike height, weight or temperature, risk from vulnerabilities is sophisticated to assess and the assessment is heavily context-dependent. Existing vulnerability assessment methodologies (e.g. CVSS scoring system, etc) mainly focus on the evaluation over intrinsic risk of individual vulnerabilities without taking their contexts into consideration. Vulnerability assessment over network usually output one aggregated metric indicating the security level of each host. However, none of these work captures the severity change of each individual vulnerabilities under different contexts. I have captured a number of such contexts for vulnerability assessment. For example, the correlation of vulnerabilities belonging to the same application should be considered while aggregating their risk scores. At system level, a vulnerability detected on a highly depended library code should be assigned with a higher risk metric than a vulnerability on a rarely used client side application, even when the two have the same intrinsic risk. Similarly at cloud environment, vulnerabilities with higher prevalences deserve more attention. Besides, zero-day vulnerabilities are largely utilized by attackers therefore should not be ignored while assessing the risks. Historical vulnerability information at application level can be used to predict underground risks. To assess vulnerability with a higher accuracy, feasibility, scalability and efficiency, I developed a systematic vulnerability assessment approach under each of these contexts. ​

<p>To test if a host contains any known security flaws over a network connection a Vulnerability Assessment (VA) could be made. This thesis describes different techniques used by VA tools over a network connection to detect known security flaws. To decrease the risk of flaws not being detected, several VA tools could be used.</p><p>There is no common way of merging information from different VA tools. Therefore the Vulnerability Assessment Information Handler (VAIH) has been developed. The VAIH system consists of three parts. First, a intermediate language format defined in XML. Second, modules that converts the output of VA tools to the intermediate language format. Third, a program for reading and displaying the intermediate language format.</p><p>The VAIH system makes it possible to merge the results from vulnerability assessment tools into one file that can be displayed and edited through a GUI.</p>

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Instalações industriais possuem uma ampla fonte de riscos. Por isso, o entendimento e gerenciamento destes adquirem grande importância para a garantia dos níveis de segurança. A temática vulnerabilidade é relevante na medida em que a relação do seu conceito ao de risco permite a contextualização deste último. A finalidade da avaliação da vulnerabilidade é descrever, dentro de um determinado contexto, a interação entre os riscos, a comunidade e o meio ambiente. Pesquisas deste tipo fornecem subsídios para o desenvolvimento de programas e estratégias de prevenção de riscos e promoção da saúde. Estudos que privilegiem a vulnerabilidade do entorno de plantas industriais ainda são escassos, porém de suma importância, pois os resultados visualizados na forma de mapas são úteis para a formulação de propostas e melhorias no gerenciamento dos riscos. Devido às características existentes nas áreas de entorno das plantas industriais no Brasil e, dada a gravidade e extensão dos danos que possíveis acidentes podem causar à saúde humana, a problemática da vulnerabilidade aos acidentes tecnológicos pode e deve ser encarada como um assunto pertinente para Saúde Pública, sendo esta área do conhecimento capaz de contribuir na formulação de estratégias de controle e prevenção de tais fatalidades. O objetivo dessa dissertação foi a aplicação do mapeamento da vulnerabilidade da área de entorno do distrito industrial do município de Paulínia e, então, a identificação dos alvos mais sensíveis à ocorrência de acidentes, a ponderação da viabilidade da aplicação deste para o contexto brasileiro e seu uso como instrumento de gestão de uso do solo no entorno de plantas industriais. A metodologia baseou-se em revisão da literatura, composição de base de dados e uso de um Sistema de Informação Geográfica. Os principais resultados indicaram valores elevados de vulnerabilidades para áreas que estão fora do limite destinado ao uso industrial, definido pelo zoneamento do município, principalmente no que diz respeito à vulnerabilidade humana. Por fim, concluiu-se que o planejamento territorial que leve em consideração a vulnerabilidade é fator primordial na redução dos danos ocasionados pelos acidentes tecnológicos, sobretudo no entorno de plantas industriais / Industrial facilities have a wide source of risk. Therefore, the understanding and management of them acquire great importance to guarantee the security levels. The vulnerability theme is relevant to the extent that its relationship with the risk concept allows the contextualization of the latter. The purpose of the vulnerability assessment is to describe, within a given context, the interaction between risks, the community and the environment. This kind of research provides subsidies for the development of programs and strategies for risk prevention and health promotion. Studies that emphasize the vulnerability of the surrounding areas of industrial plants are still scarce, but very important, because the results displayed in form of maps are useful to formulation of proposals and improvements in risk management. Due to the characteristics that are in the surrounding areas of industrial plants in Brazil and, considering the severity and extent of the damage that can cause possible injury to human health, the issue of vulnerability to technological accidents can and must be seen as a relevant subject to Public Health, and this area of knowledge can contribute to formulation of strategies for prevention and control of such fatalities. The purpose of this dissertation was the application of vulnerability mapping in the surrounding area of the industrial district at the Paulínia municipality and then, the identification of the more sensitivies targets to occurrence of accidents, the assessment of feasibility of applying this model to the Brazilian context and its use as a management tool in land use around plants. The methodology was based on a literature review, the composition of the database and the use of a Geographic Information System. The main results showed high vulnerability to areas outside limits for industrial use, defined by the municipality zoning, especially with regard to human vulnerability. Finally, it was concluded that territorial planning that takes into account the vulnerability is a key factor in reducing the damage caused by technological accidents, especially in surrounding areas of industrial plants

Introduction. Atherosclerotic plaque rupture may occur without warning leading to severe clinical events such as heart attack and stroke. The mechanisms causing plaque rupture are not well understood. It is hypothesized that mechanical forces may play an important role in the plaque rupture process and that image-based computational mechanical analysis may provide useful information for more accurate plaque vulnerability assessment. The objectives of this dissertation are: a) develop in vivo magnetic resonance imaging (MRI)-based 3D computational models with fluid-structure Interactions (FSI) for human atherosclerotic carotid plaques; b) perform mechanical analysis using 3D FSI models to identify critical stress/strain conditions which may be used for possible plaque rupture predictions. Data, Model, and Methods. Histological, ex vivo/ in vivo MRI data of human carotid plaques were provided by the University of Washington Medical School and Washington University Medical School. Blood flow was assumed to be laminar, Newtonian, viscous and incompressible. The Navier-Stokes equations with arbitrary Lagrangian-Eulerian (ALE) formulation were used as the governing equations for the flow model. The vessel and plaque components were assumed to be hyperelastic, isotropic, nearly-incompressible and homogeneous. The nonlinear Mooney-Rivlin model was used to describe the nonlinear properties of the materials with parameter values chosen to match available experimental data. The fully-coupled FSI models were solved by a commercial finite element software ADINA to obtain full 3D flow and stress/strain distributions for analysis. Validation of the computational models and Adina software were provided by comparing computational solutions with analytic solutions and experimental data. Several novel methods were introduced to address some fundamental issues for construction of in vivo MRI-based 3D FSI models: a) an automated MRI segmentation technique using a Bayes theorem with normal probability distribution was implemented to obtain plaque geometry with enclosed components; b) a pre-shrink process was introduced to shrink the in vivo MRI geometry to obtain the no-load shape of the plaque; c) a Volume Component-Fitting Method was introduced to generate a 3D computational mesh for the plaque model with deformable complex geometry, FSI and inclusions; d) a method using MRI data obtained under in vitro pressurized conditions was introduced to determine vessel material properties. Results. The effects of material properties on flow and wall stress/strain behaviors were evaluated. The results indicate that a 100% stiffness increase may decrease maximal values of maximum principal stress (Stress-P1) and maximum principal strain (Strain-P1) by about 20% and 40%, respectively; flow Maximum-Shear-Stress (FMSS) and flow velocity did not show noticeable changes. By comparing ex vivo and in vivo data of 10 plaque samples, the average axial (25%) and inner circumferential (7.9%) shrinkages of the plaques between loaded and unloaded state were obtained. Effects of the shrink-stretch process on plaque stress/strain distributions were demonstrated based on six adjusted 3D FSI models with different shrinkages. Stress-P1 and Strain-P1 increased 349.8% and 249% respectively with 33% axial stretch. The effects of a lipid-rich necrotic core and fibrous cap thickness on structure/flow behaviors were investigated. The mean values of wall Stress-P1 and Strain-P1 from lipid nodes from a ruptured plaque were significantly higher than those from a non-ruptured plaque (112.3 kPa, 0.235 & 80.1 kPa, 0.185), which was 40.2% and 26.8% higher, respectively (p<0.001). High stress/strain concentrations were found at the thin fibrous cap regions. These results indicate that high stress concentrations and thin fibrous cap thickness might be critical indicators for plaque vulnerability. Conclusion. In vivo image-based 3D FSI models and mechanical image analysis may have the potential to provide quantitative risk indicators for plaque vulnerability assessment.

Instalações industriais possuem uma ampla fonte de riscos. Por isso, o entendimento e gerenciamento destes adquirem grande importância para a garantia dos níveis de segurança. A temática vulnerabilidade é relevante na medida em que a relação do seu conceito ao de risco permite a contextualização deste último. A finalidade da avaliação da vulnerabilidade é descrever, dentro de um determinado contexto, a interação entre os riscos, a comunidade e o meio ambiente. Pesquisas deste tipo fornecem subsídios para o desenvolvimento de programas e estratégias de prevenção de riscos e promoção da saúde. Estudos que privilegiem a vulnerabilidade do entorno de plantas industriais ainda são escassos, porém de suma importância, pois os resultados visualizados na forma de mapas são úteis para a formulação de propostas e melhorias no gerenciamento dos riscos. Devido às características existentes nas áreas de entorno das plantas industriais no Brasil e, dada a gravidade e extensão dos danos que possíveis acidentes podem causar à saúde humana, a problemática da vulnerabilidade aos acidentes tecnológicos pode e deve ser encarada como um assunto pertinente para Saúde Pública, sendo esta área do conhecimento capaz de contribuir na formulação de estratégias de controle e prevenção de tais fatalidades. O objetivo dessa dissertação foi a aplicação do mapeamento da vulnerabilidade da área de entorno do distrito industrial do município de Paulínia e, então, a identificação dos alvos mais sensíveis à ocorrência de acidentes, a ponderação da viabilidade da aplicação deste para o contexto brasileiro e seu uso como instrumento de gestão de uso do solo no entorno de plantas industriais. A metodologia baseou-se em revisão da literatura, composição de base de dados e uso de um Sistema de Informação Geográfica. Os principais resultados indicaram valores elevados de vulnerabilidades para áreas que estão fora do limite destinado ao uso industrial, definido pelo zoneamento do município, principalmente no que diz respeito à vulnerabilidade humana. Por fim, concluiu-se que o planejamento territorial que leve em consideração a vulnerabilidade é fator primordial na redução dos danos ocasionados pelos acidentes tecnológicos, sobretudo no entorno de plantas industriais / Industrial facilities have a wide source of risk. Therefore, the understanding and management of them acquire great importance to guarantee the security levels. The vulnerability theme is relevant to the extent that its relationship with the risk concept allows the contextualization of the latter. The purpose of the vulnerability assessment is to describe, within a given context, the interaction between risks, the community and the environment. This kind of research provides subsidies for the development of programs and strategies for risk prevention and health promotion. Studies that emphasize the vulnerability of the surrounding areas of industrial plants are still scarce, but very important, because the results displayed in form of maps are useful to formulation of proposals and improvements in risk management. Due to the characteristics that are in the surrounding areas of industrial plants in Brazil and, considering the severity and extent of the damage that can cause possible injury to human health, the issue of vulnerability to technological accidents can and must be seen as a relevant subject to Public Health, and this area of knowledge can contribute to formulation of strategies for prevention and control of such fatalities. The purpose of this dissertation was the application of vulnerability mapping in the surrounding area of the industrial district at the Paulínia municipality and then, the identification of the more sensitivies targets to occurrence of accidents, the assessment of feasibility of applying this model to the Brazilian context and its use as a management tool in land use around plants. The methodology was based on a literature review, the composition of the database and the use of a Geographic Information System. The main results showed high vulnerability to areas outside limits for industrial use, defined by the municipality zoning, especially with regard to human vulnerability. Finally, it was concluded that territorial planning that takes into account the vulnerability is a key factor in reducing the damage caused by technological accidents, especially in surrounding areas of industrial plants

The requirements to protect public water systems from intentional contamination have expanded in the years following September 11, 2001. The areal extent and non-linear nature of water demand and movement in the distribution system makes efficient location of sampling points difficult. This difficulty is compounded by the fact that contamination conceptually can occur at any point and at any time within the distribution system. Small to mid-sized water systems are especially at a disadvantage in addressing this issue due to limited resources available to them. This paper proposes a heuristic methodology to identify strategic locations within the system that can be established as critical detection points for such occurrences. The process uses off-the-shelf software and is structured to be accessible to small and mid-sized water system managers. This methodology is different from others proposed in the literature in that it uses computer simulations to create a database of water system response to contamination at every node in the system. A process is developed to mine this database systematically after considering concentration thresholds and "time since injection" parameters. Finally, using pivot tables and graphs, a network of monitoring locations is identified to provide efficient coverage of the system under the conditions imposed.

The aim of the study is to develop new analytical fragility curves for the vulnerability assessment of tunnels based on actual damage data of tunnels obtained from past earthquakes. For this purpose, additional important damage data belonging to Bolu Tunnels, Turkey was utilized as a case study. Bolu Tunnels constitute a very interesting case from the earthquake hazard point of view, since two major earthquakes, 17 August 1999 Marmara and 12 November 1999 D&uuml / zce, occurred during the construction of the tunnels. The August 17, 1999 earthquake was reported to have had minimal impact on the Bolu Tunnels. However, the November 12, 1999 earthquake caused some sections of both tunnels to collapse. The remaining sections of the tunnels survived with various damage states which were subsequently documented in detail. This valuable damage data was thoroughly utilized in this study. To develop analytical fragility curves, the methodology described by Argyroudis et al. (2007) was followed. Seismic response of the Tunnels was assessed using analytical, pseudo-static and full-dynamic approaches. In this way, it was possible to make comparisons regarding the dynamic analysis methods of tunnels to predict the seismically induced damage. Compared to the pseudo-static and full-dynamic methods, the predictive capability of the analytical method is found to be relatively low due to limitations inherent to this method. The pseudo-static and full-dynamic solution results attained appear to be closer to each other and better represented the recorded damage states in general. Still, however, the predictive capability of the pseudo-static approach was observed to be limited for particular cases with reference to the full-dynamic method, especially for the sections with increasingly difficult ground conditions. The final goal of this study is the improvement of damage indexes corresponding to the defined damage states which were proposed by Argyroudis et al. (2005) based on the previous experience of damages in tunnels and engineering judgment. These damage indexes were modified in accordance with the findings from the dynamic analyses and actual damage data documented from Bolu Tunnels following the D&uuml / zce earthquake. Three damage states were utilized to quantify the damage in this study.