25,604 research outputs found

    A personal networking solution

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    This paper presents an overview of research being conducted on Personal Networking Solutions within the Mobile VCE Personal Distributed Environment Work Area. In particular it attempts to highlight areas of commonality with the MAGNET initiative. These areas include trust of foreign devices and service providers, dynamic real-time service negotiation to permit context-aware service delivery, an automated controller algorithm for wireless ad hoc networks, and routing protocols for ad hoc networking environments. Where possible references are provided to Mobile VCE publications to enable further reading

    A resource management architecture for future mobile communications systems

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    This paper presents an overview of a hierarchical Resource Management architecture for future mobile communications systems. The architecture is designed to be generic and can therefore be adopted for a range of Radio Access Methodologies. In particular it provides a mechanism for radio resource management across airinterfaces such as those being defined for use with UMTS. Given the move towards packet-switched technologies both in the Core Network and the Radio Access Network [1], the architecture embraces the concept of statistical QoS applied to individual flows in the form of a commitment level. I

    Securing personal distributed environments

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    The Personal Distributed Environment (PDE) is a new concept being developed by Mobile VCE allowing future mobile users flexible access to their information and services. Unlike traditional mobile communications, the PDE user no longer needs to establish his or her personal communication link solely through one subscribing network but rather a diversity of disparate devices and access technologies whenever and wherever he or she requires. Depending on the services’ availability and coverage in the location, the PDE communication configuration could be, for instance, via a mobile radio system and a wireless ad hoc network or a digital broadcast system and a fixed telephone network. This new form of communication configuration inherently imposes newer and higher security challenges relating to identity and authorising issues especially when the number of involved entities, accessible network nodes and service providers, builds up. These also include the issue of how the subscribed service and the user’s personal information can be securely and seamlessly handed over via multiple networks, all of which can be changing dynamically. Without such security, users and operators will not be prepared to trust their information to other networks

    A personal distributed environment for future mobile systems

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    A Personal Distributed Environment (PDE) embraces a user-centric view of communications that take place against a backdrop of multiple user devices, each with its distinct capabilities, in physically separate locations. This paper provides an overview of a Personal Distributed Environment and some of the research issues related to the implementation of the PDE concept that are being considered in the current Mobile VCE work programme

    Design and evaluation of dynamic policy-based flow redirection for multihomed mobile netwotks

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    This paper presents the design, implementation and evaluation of a solution for dynamic redirection of traffic flows for multihomed mobile networks. The solution was developed for a mobile user that disposes of a Personal Area Network (PAN) with a Personal Mobile Router (PMR), in order to achieve Always Best Connected(ABC) service by distributing flows belonging to different applications among the most appropriate access networks. Designed in a modular way for a NEMO based mobility and multihoming support, the proposed flow redirection solution can be easily coupled with and controlled by dynamic traffic policies that come from advanced network intelligence, according to the currently available network resources and user and application requirements. A prototype implementation was validated and assessed on a testbed as proof-of-concept

    Cotton Futures Dynamics: Structural Change, Index Traders and the Returns to Storage

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    The commodity bull cycle of 2006-2008 and subsequent dramatic price decline have been a source of hardship for traditional commodity market participants such as producers and merchant/shippers. The usefulness of futures markets has been called into question, especially given that some market movements did not appear to be justified by economic fundamentals. An emerging research literature examines the possible influence of futures traders, and particularly the non-traditional Index Traders, on the well-functioning of futures markets and underlying commodity markets. Cotton is a relatively under-studied commodity that is of particular importance for producers in the South and Southwest. To this end, this paper asks the following questions: (1) What role have (primarily long-only) Index Traders played, if we simultaneously account for important ongoing changes in cotton economic fundamentals? (2) Have seasonal and long-run patterns of convenience yield and price volatility changed during or since the commodity bull cycle? (3) How well do the data support a theory of storage model using the concept of convenience yield, and has the relationship changed with the commodity bull cycle? The results presented in this paper suggest that traditional, well-established economic relationships for cotton futures markets clearly have been disrupted during the period 2006- 2009. However, we find no direct evidence to support the claim that Index Traders are responsible for changes in prices or volatility.Cotton, futures markets, theory of storage, convenience yield, Index Traders, Agribusiness, Agricultural Finance, Crop Production/Industries, Demand and Price Analysis, Farm Management, Financial Economics, Marketing, Research Methods/ Statistical Methods, Risk and Uncertainty,

    Defragmentation measures and the increase of a local European badger (Meles meles) population at Eindegooi, the Netherlands

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    Ontsnipperingsmaatregelen en de groei van de lokale dassenpopulatie (Meles meles) op Eindegooi . Vanaf 1984 zijn gegevens verzameld op het landgoed Eindegoed en omgeving. De das koloniseerde nieuwe terreinen. In dezelfde periode zijn vele ontsnipperende maatregelen bij wegen getroffen

    Checking the validity of truncating the cumulant hierarchy description of a small system

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    We analyze the behavior of the first few cumulant in an array with a small number of coupled identical particles. Desai and Zwanzig (J. Stat. Phys., {\bf 19}, 1 (1978), p. 1) studied noisy arrays of nonlinear units with global coupling and derived an infinite hierarchy of differential equations for the cumulant moments. They focused on the behavior of infinite size systems using a strategy based on truncating the hierarchy. In this work we explore the reliability of such an approach to describe systems with a small number of elements. We carry out an extensive numerical analysis of the truncated hierarchy as well as numerical simulations of the full set of Langevin equations governing the dynamics. We find that the results provided by the truncated hierarchy for finite systems are at variance with those of the Langevin simulations for large regions of parameter space. The truncation of the hierarchy leads to a dependence on initial conditions and to the coexistence of states which are not consistent with the theoretical expectations based on the multidimensional linear Fokker-Planck equation for finite arrays

    Coronal Fe XIV Emission During the Whole Heliosphere Interval Campaign

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    Solar Cycle 24 is having a historically long and weak start. Observations of the Fe XIV corona from the Sacramento Peak site of the National Solar Observatory show an abnormal pattern of emission compared to observations of Cycles 21, 22, and 23 from the same instrument. The previous three cycles have shown a strong, rapid "Rush to the Poles" (previously observed in polar crown prominences and earlier coronal observations) in the parameter N(t,l,dt) (average number of Fe XIV emission features per day over dt days at time t and latitude l). Cycle 24 displays a weak, intermittent, and slow "Rush" that is apparent only in the northern hemisphere. If the northern Rush persists at its current rate, evidence from the Rushes in previous cycles indicates that solar maximum will occur in early 2013 or late 2012, at least in the northern hemisphere. At lower latitudes, solar maximum previously occurred when the time maximum of N(t,l,365) reached approximately 20{\deg} latitude. Currently, this parameter is at or below 30{\deg}and decreasing in latitude. Unfortunately, it is difficult at this time to calculate the rate of decrease in N(t,l,365). However, the southern hemisphere could reach 20{\deg} in 2011. Nonetheless, considering the levels of activity so far, there is a possibility that the maximum could be indiscernibleComment: 8 pages, 4 figures; Solar Physics Online First, 2011 http://www.springerlink.com/content/b5kl4040k0626647

    Variable stars in the VVV globular clusters

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    Indexación: Scopus.The VVV survey observed some of the most crowded and most obscured regions in the inner Milky Way during the last years. A significant sample of the less known globular clusters in our galaxy lie there. Combining the high-resolution, wide-field, near infrared capabilities of the survey camera, the use of 5 different filters, and multi-epoch observations, we are able to overcome many of the previous challenges that prevented a proper study of these objects. Particularly, the identification of the RR Lyrae stars in these globular clusters is proving to be a fundamental tool to establish accurately their distances and reddenings, and to infer information about the Oosterhoff dichotomy that Galactic globular clusters seem to follow. © The Authors, published by EDP Sciences, 2017.https://www.epj-conferences.org/articles/epjconf/pdf/2017/21/epjconf_puls2017_01022.pd
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