40,767 research outputs found

    Security in Wireless Medical Networks

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    A comparison of classical scheduling approaches in power-constrained block-test scheduling

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    Classical scheduling approaches are applied here to overcome the problem of unequal-length block-test scheduling under power dissipation constraints. List scheduling-like approaches are proposed first as greedy algorithms to tackle the fore mentioned problem. Then, distribution-graph based approaches are described in order to achieve balanced test concurrency and test power dissipation. An extended tree growing technique is also used in combination with these classical approaches in order to improve the test concurrency having assigned power dissipation limits. A comparison between the results of the test scheduling experiments highlights the advantages and disadvantages of applying different classical scheduling algorithms to the power-constrained test scheduling proble

    Coding-theorem Like Behaviour and Emergence of the Universal Distribution from Resource-bounded Algorithmic Probability

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    Previously referred to as `miraculous' in the scientific literature because of its powerful properties and its wide application as optimal solution to the problem of induction/inference, (approximations to) Algorithmic Probability (AP) and the associated Universal Distribution are (or should be) of the greatest importance in science. Here we investigate the emergence, the rates of emergence and convergence, and the Coding-theorem like behaviour of AP in Turing-subuniversal models of computation. We investigate empirical distributions of computing models in the Chomsky hierarchy. We introduce measures of algorithmic probability and algorithmic complexity based upon resource-bounded computation, in contrast to previously thoroughly investigated distributions produced from the output distribution of Turing machines. This approach allows for numerical approximations to algorithmic (Kolmogorov-Chaitin) complexity-based estimations at each of the levels of a computational hierarchy. We demonstrate that all these estimations are correlated in rank and that they converge both in rank and values as a function of computational power, despite fundamental differences between computational models. In the context of natural processes that operate below the Turing universal level because of finite resources and physical degradation, the investigation of natural biases stemming from algorithmic rules may shed light on the distribution of outcomes. We show that up to 60\% of the simplicity/complexity bias in distributions produced even by the weakest of the computational models can be accounted for by Algorithmic Probability in its approximation to the Universal Distribution.Comment: 27 pages main text, 39 pages including supplement. Online complexity calculator: http://complexitycalculator.com

    User-differentiated hierarchical key management for the bring-your-own-device environments

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    To ensure confidentiality, the sensitive electronic data held within a corporation is always carefully encrypted and stored in a manner so that it is inaccessible to those parties who are not involved. During this process, the specific manners of how to keep, distribute, use, and update keys which are used to encrypt the sensitive data become an important thing to be considered. Through use of hierarchical key management, a technique that provides access controls in multi-user systems where a portion of sensitive resources shall only be made available to authorized users or security ordinances, required information is distributed on a need-to-know basis. As a result of this hierarchical key management, time-bound hierarchical key management further adds time controls to the information access process. There is no existing hierarchical key management scheme or time-bound hierarchical key management scheme which is able to differentiate users with the same authority. When changes are required for any user, all other users who have the same access authorities will be similarly affected, and this deficiency then further deteriorates due to a recent trend which has been called Bring-Your-Own-Device. This thesis proposes the construction of a new time-bound hierarchical key management scheme called the User-Differentiated Two-Layer Encryption-Based Scheme (UDTLEBC), one which is designed to differentiate between users. With this differentiation, whenever any changes are required for one user during the processes of key management, no additional users will be affected during these changes and these changes can be done without interactions with the users. This new scheme is both proven to be secure as a time-bound hierarchical key management scheme and efficient for use in a BYOD environment
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