7,343 research outputs found
Assessing and augmenting SCADA cyber security: a survey of techniques
SCADA systems monitor and control critical infrastructures of national importance such as power generation and distribution, water supply, transportation networks, and manufacturing facilities. The pervasiveness, miniaturisations and declining costs of internet connectivity have transformed these systems from strictly isolated to highly interconnected networks. The connectivity provides immense benefits such as reliability, scalability and remote connectivity, but at the same time exposes an otherwise isolated and secure system, to global cyber security threats. This inevitable transformation to highly connected systems thus necessitates effective security safeguards to be in place as any compromise or downtime of SCADA systems can have severe economic, safety and security ramifications. One way to ensure vital asset protection is to adopt a viewpoint similar to an attacker to determine weaknesses and loopholes in defences. Such mind sets help to identify and fix potential breaches before their exploitation. This paper surveys tools and techniques to uncover SCADA system vulnerabilities. A comprehensive review of the selected approaches is provided along with their applicability
Flexible Product Line Derivation applied to a Model Based Systems Engineering process
soumis a CSDM 2012Systems engineering enables the successful realization of systems, focusing on defining customer needs early in the development cycle. However there is a lack of methodological support when the development of systems needs to rely on legacy system designs. Furthermore, in the automotive domain, product diversity increases system complexity so much, that reuse becomes much more difficult and time con- suming than usually. We believe a specific strategy must be adopted to prepare for reuse and to achieve systems engineering by reuse. While product line derivation provides the means to obtain single products form a collection of assets, there is still little support for integration with systems engineering practices. In this paper we present an approach which takes into account systems engineering methodolog- ical aspects in product line engineering by rendering the derivation process more flexible. We present the implementation of the tool support for our approach based on the Papyrus1 SysML modeller and exemplify the concepts through a derivation example of the electric parking brake system
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Initialisation Problems in Feature Composition
Composing features that have inconsistent requirements may lead to feature interactions that violate requirements satisfied by each feature in isolation. These interactions manifest themselves as conflicts on shared resources. Arbitration is a common approach to resolving such conflicts that uses prioritisation to decide which feature has access to resources when there is a conflict. However, arbitration alone does not guarantee satisfaction of the requirement of the feature that eventually gains access to a resource. This is because arbitration does not take into account that the resource may be in a state that is inconsistent with that expected by the feature. We call this the initialisation problem.
In this thesis we propose an approach to addressing the initialisation problem which combines arbitration with contingencies. Contingency means having several specifications per feature satisfying the same requirement, depending on the current resource state. We illustrate and validate our approach by applying it to resolving conflicts between features in smart home and automotive domains. The validation shows that contingencies complement arbitration by enabling satisfaction of the requirement of the feature that eventually gains access to a shared resource, regardless of the current state of the resource.
The main contribution of this thesis is an approach to analysing initialisation concerns in feature composition. At the core of our approach is an explicit consideration of all possible states of a resource as potential initial states. Given each initial state we then derive corresponding specifications that would enable a feature to satisfy its requirement in those states. We show that our approach to initialisation problems is relevant to addressing the feature interaction problem by characterising some types of conflicts as initialisation concerns
Learning Behavior Models for Interpreting and Predicting Traffic Situations
In this thesis, we present Bayesian state estimation and machine learning methods for predicting traffic situations. The cognitive ability to assess situations and behaviors of traffic participants, and to anticipate possible developments is an essential requirement for several applications in the traffic domain, especially for self-driving cars. We present a method for learning behavior models from unlabeled traffic observations and develop improved learning methods for decision trees
SiSeRHMap v1.0: A simulator for mapped seismic response using a hybrid model
SiSeRHMap is a computerized methodology capable of drawing up prediction maps of
seismic response. It was realized on the basis of a hybrid model which combines different
approaches and models in a new and non-conventional way. These approaches
5 and models are organized in a code-architecture composed of five interdependent
modules. A GIS (Geographic Information System) Cubic Model (GCM), which is a layered
computational structure based on the concept of lithodynamic units and zones,
aims at reproducing a parameterized layered subsoil model. A metamodeling process
confers a hybrid nature to the methodology. In this process, the one-dimensional linear
10 equivalent analysis produces acceleration response spectra of shear wave velocitythickness
profiles, defined as trainers, which are randomly selected in each zone. Subsequently,
a numerical adaptive simulation model (Spectra) is optimized on the above
trainer acceleration response spectra by means of a dedicated Evolutionary Algorithm
(EA) and the Levenberg–Marquardt Algorithm (LMA) as the final optimizer. In the fi15
nal step, the GCM Maps Executor module produces a serial map-set of a stratigraphic
seismic response at different periods, grid-solving the calibrated Spectra model. In addition,
the spectra topographic amplification is also computed by means of a numerical
prediction model. This latter is built to match the results of the numerical simulations
related to isolate reliefs using GIS topographic attributes. In this way, different sets
20 of seismic response maps are developed, on which, also maps of seismic design response
spectra are defined by means of an enveloping technique
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