Collecting and Analyzing Failure Data of Bluetooth Personal Area Networks

This work presents a failure data analysis campaign on Bluetooth Personal Area Networks (PANs) conducted on two kind of heterogeneous testbeds (working for more than one year). The obtained results reveal how failures distribution are characterized and suggest how to improve the dependability of Bluetooth PANs. Specically, we dene the failure model and we then identify the most effective recovery actions and masking strategies that can be adopted for each failure. We then integrate the discovered recovery actions and masking strategies in our testbeds, improving the availability and the reliability of 3.64% (up to 36.6%) and 202% (referred to the Mean Time To Failure), respectively

Analytical computation of the off-axis Effective Area of grazing incidence X-ray mirrors

Focusing mirrors for X-ray telescopes in grazing incidence, introduced in the 70s, are characterized in terms of their performance by their imaging quality and effective area, which in turn determines their sensitivity. Even though the on-axis effective area is assumed in general to characterize the collecting power of an X-ray optic, the telescope capability of imaging extended X-ray sources is also determined by the variation in its effective area with the off-axis angle. [...] The complex task of designing optics for future X-ray telescopes entails detailed computations of both imaging quality and effective area on- and off-axis. Because of their apparent complexity, both aspects have been, so far, treated by using ray-tracing routines aimed at simulating the interaction of X-ray photons with the reflecting surfaces of a given focusing system. Although this approach has been widely exploited and proven to be effective, it would also be attractive to regard the same problem from an analytical viewpoint, to assess an optical design of an X-ray optical module with a simpler calculation than a ray-tracing routine. [...] We have developed useful analytical formulae for the off-axis effective area of a double-reflection mirror in the double cone approximation, requiring only an integration and the standard routines to calculate the X-ray coating reflectivity for a given incidence angle. [...] Algebraic expressions are provided for the mirror geometric area, as a function of the off-axis angle. Finally, the results of the analytical computations presented here are validated by comparison with the corresponding predictions of a ray-tracing code.Comment: 12 pages, 11 figures, accepted for publication in "Astronomy & Astrophysics", section "Instruments, observational techniques, and data processing". Updated version after grammatical revision and typos correctio

Integrated Support for Handoff Management and Context-Awareness in Heterogeneous Wireless Networks

The overwhelming success of mobile devices and wireless communications is stressing the need for the development of mobility-aware services. Device mobility requires services adapting their behavior to sudden context changes and being aware of handoffs, which introduce unpredictable delays and intermittent discontinuities. Heterogeneity of wireless technologies (Wi-Fi, Bluetooth, 3G) complicates the situation, since a different treatment of context-awareness and handoffs is required for each solution. This paper presents a middleware architecture designed to ease mobility-aware service development. The architecture hides technology-specific mechanisms and offers a set of facilities for context awareness and handoff management. The architecture prototype works with Bluetooth and Wi-Fi, which today represent two of the most widespread wireless technologies. In addition, the paper discusses motivations and design details in the challenging context of mobile multimedia streaming applications

Algorithms in behavioral systems theory

Een van de belangrijkste eigenschappen van systemen is hun complexiteit en hun interconnectiviteit. Een manier om dergelijke systemen te bestuderen is door ze te beschouwen als bestaande uit interacterende deelsystemen. Typische voorbeelden van complexe systemen die opgebouwd zijn uit eenvoudige deelsystemen zijn electrische netwerken met als bouwstenen weerstanden, capaciteiten, transistoren, enz., mechanische systemen met als bouwstenen massa's, veren, dempers, enz., mechatronische systemen zoals robots, verder, chemische plants, enz. Dit proefschrift behandelt het mathematisch modelleren van dergelijke geïnterconnecteerde systemen ... Zie: Samenvattin

Alien Registration- Cotroneo, Nina (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/25811/thumbnail.jp

470— Quantifying the Shape of a Plant (\u3ci\u3eBrassica rapa\u3c/i\u3e) During Growth Under Different Light Intensities Using Fractal Geometry

Over time plants not only increase in size but also change their shape. Quantifying this change in shape, however, is challenging. Fractal dimension, a measure of how these plants fill space, can provide a wholistic understanding of plant shape and how that shape changes as the plants react to their environments. I used a high-resolution, three-dimensional scanner to estimate the shape of Brassica rapa plants during growth under three different light intensities: low (40 Einsteins), medium (75 Einsteins) and high (100 Einsteins). From these data, each plant\u27s above-ground shape was quantified using fractal geometry. The fractal dimension (D) of plants grown under the low and medium light conditions increased asymptotically with growth rates 0.13769 and 0.16009, respectively, to fractal dimension 1.660 and 1.640, respectively. Plants grown under high light had a mean constant fractal dimension of 1.524 over the course of the experiment. I developed a 3-dimensional diffusion-limited aggregation model of plant growth over time which accounts for light intensity in order to test whether this simple set of rules can simulate plants with a similar shape. Results suggest that the model is capable of generating plants with a fractal dimension growth curve comparable to that of experimentally grown plants

Alien Registration- Cotroneo, John (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/25810/thumbnail.jp