7 research outputs found
Notfallschutz und Risk Governance: Zur nuklearen Sicherheit bei KernkraftwerksunfÀllen
Die Arbeit mit dem Titel âNotfallschutz und Nuclear Risk Governance: Zur nuklearen Sicherheit
bei KernkraftwerksunfĂ€llenâ beschĂ€ftigt sich mit Fragen der Sicherheit von Mensch und Umwelt
vor den Gefahren der Kernenergie und den schÀdlichen Wirkungen der RadioaktivitÀt bei
KernkraftwerksunfĂ€llen. Ăbergeordnete Ziele sind, UnzulĂ€nglichkeiten und Defizite, die bei der
BewÀltigung von schweren KernkraftunfÀllen z.B. 1986 in Tschernobyl und 2011 in Fukushima
aufgetreten sind, zu identifizieren und aufzuzeigen, wie ein internationale Regime beschaffen sein
sollte, das zu einer Verbesserung und internationalen Harmonisierung von Planungen und
MaĂnahmen im nuklearen Notfallschutz fĂŒhrt.The present study entitled "Emergency Response and Nuclear Risk Governance : nuclear safety at
nuclear power plant accidents" deals with issues of the protection of the population and the
environment against hazardous radiation (the hazards of nuclear energy) and the harmful effects of
radioactivity during nuclear power plant accidents. The aim of this study is to contribute to both
the identification and remediation of shortcomings and deficits in the management of severe
nuclear accidents like those that occurred at Chernobyl in 1986 and at Fukushima in 2011 as well
as to the improvement and harmonization of plans and measures taken on an international level in
nuclear emergency management
Protocols for the efficient dissemination of context-aware messages
Context-aware applications are able to react and adapt to the context of their users. This context includes, for instance, location, properties of the user or their surroundings, nearby devices, etc. Over the last years, powerful mobile devices, i.e., smartphones or tablet computers, have become an important part in many people's computing life. Most of these devices maintain a continuous high-speed network connection, allowing to provide distributed applications with an uninterrupted stream of data. Additionally, a huge number of sensors, both in these mobile devices and deployed in our surroundings, enable the creation of comprehensive context models. Such large-scale context models open up new possibilities for the development of context-aware applications by providing access to relevant context information from providers all over the world.
However, until now, applications need to query the context model for relevant information or register for events or messages; it is not possible to "push" information to the mobile devices, neither from the infrastructure nor from other mobile devices. To support application developers, we propose Contextcast, a novel communication paradigm that allows for the dissemination of context-aware (or contextual) messages in a system of context-aware routers. This includes the fundamental semantics to address clients using context constraints and a reference dissemination scheme for such messages.
To enable Contextcast to grow to scales similar to the context-aware systems that it is intended to be used with, we also propose a couple of optimized routing approaches. They are designed to reduce the number of maintenance messages that are necessary for the dissemination of contextual messages. One optimized routing algorithm uses coarse context information to reduce the amount of context updates propagated to routers. To this end, routers use the similarity of contexts to automatically find groups of similar clients, whose information can then be propagated as a single, coarse context. While this reduces the amount of context information to be propagated, the resulting information loss causes more messages to be forwarded, since routers no longer possess exact information to match against the constraints in contextual messages. A configurable similarity threshold allows for various trade-offs between the coarseness of the context information and the resulting additional message load. The second orthogonal routing approach relies on statistics to determine the characteristics of contexts and messages in the system. Without context knowledge, routers must assume the presence of a matching recipient and forward a message speculatively to disseminate it to all recipients. Using statistics, routers can determine how often certain messages occur and then calculate the benefit of propagating contexts corresponding to these messages. Several parameters enable an administrator to adjust how fast the system reacts to changes, depending on the observed messages and context updates.
Additionally, temporal support extends Contextcast with a powerful mechanism that allows application developers and clients to address messages to certain contexts in the past or future. This includes an additional context attribute \cattr{time} and a constraint with various, easy to use temporal operators. We also propose efficient routing approaches for historical and future messages. Routing historical messages focuses on efficient routing while effectively protecting the clients' privacy, i.e., their respective context history. The routing approach for future messages delays forwarding messages until a matching context is registered, thus preventing needlessly forwarded messages