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

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

Use of synchrotron tomographic techniques in the assessment of diffusion parameters for solute transport in groundwater flow

This technical note describes the use of time-resolved synchrotron radiation tomographic energy dispersive diffraction imaging (TEDDI) and tomographic X-ray fluorescence (TXRF) for examining ion diffusion in porous media. The technique is capable of tracking the diffusion of several ion species simultaneously. This is illustrated by results which compare the movement of Cs+, Ba2+ and La3+ ions from solution into a typical sample of English chalk. The results exhibited somewhat anomalous (non-Fickian) behaviour and revealed heterogeneities (in 1D) on the scale of a few millimetres

Suppression of line voltage related distortion in current controlled grid connected inverters

The influence of selected control strategies on the level of low-order current harmonic distortion generated by an inverter connected to a distorted grid is investigated through a combination of theoretical and experimental studies. A detailed theoretical analysis, based on the concept of harmonic impedance, establishes the suitability of inductor current feedback versus output current feedback with respect to inverter power quality. Experimental results, obtained from a purpose-built 500-W, three-level, half-bridge inverter with an L-C-L output filter, verify the efficacy of inductor current as the feedback variable, yielding an output current total harmonic distortion (THD) some 29% lower than that achieved using output current feedback. A feed-forward grid voltage disturbance rejection scheme is proposed as a means to further reduce the level of low-order current harmonic distortion. Results obtained from an inverter with inductor current feedback and optimized feed-forward disturbance rejection show a THD of just 3% at full-load, representing an improvement of some 53% on the same inverter with output current feedback and no feed-forward compensation. Significant improvements in THD were also achieved across the entire load range. It is concluded that the use of inductor current feedback and feed-forward voltage disturbance rejection represent cost–effect mechanisms for achieving improved output current quality

Elimination of subharmonics in direct look-up table (DLT) sine wave reference generators for low-cost microprocessor-controlled inverters

This paper investigates distortion of an inverter reference waveform generated using a direct look-up (DLT) algorithm. The sources of various distortion components are identified and the implications for application to variable speed drives and grid connected inverters are described. Harmonic and subharmonic distortion mechanisms are analyzed, and compared with experimental results. Analytical methods are derived to determine the occurrence of subharmonics, their number, frequencies and maximum amplitudes. A relationship is established identifying a discrete set of synthesizable frequencies which avoid sub-harmonic distortion as a function of look-up table length and a practical method for calculation of the look-up table indices, based on finite length binary representation, is presented. Real time experimental results are presented to verify the analytical derivations

Contributions to workload of rotational optical transformations

An investigation of visuomotor adaptation to optical rotation and optical inversion was conducted. Experiment 1 examined the visuomotor adaptability of subjects to an optically rotating visual world with a univariate repeated measures design. Experiment 1A tested one major prediction of a model of adaptation put forth by Welch who predicted that the aversive drive state that triggers adaptation would be habituated to fairly rapidly. Experiment 2 was conducted to investigate the role of motor activity in adaptation to optical rotation. Specifically, this experiment contrasted the reafference hypothesis and the proprioceptive change hypothesis. Experiment 3 examined the role of cognition, error-corrective feedback, and proprioceptive and/or reafferent feedback in visuomotor adaptation to optical inversion. Implications for research and implications for practice were suggested for all experiments

Inter-sensory Judgments of Signal Duration

Intersensory discrimination of signal duration using visual and auditory signal

Solving the Schwinger-Dyson Equations for Gluodynamics in the Maximal Abelian Gauge

We derive the Schwinger-Dyson equations for the SU(2) Yang-Mills theory in the maximal Abelian gauge and solve them in the infrared asymptotic region. We find that the infrared asymptotic solutions for the gluon and ghost propagators are consistent with the hypothesis of Abelian dominance.Comment: 3 pages, 1 figure; Lattice2003(topology

Collaborative adaptive accessibility and human capabilities

This thesis discusses the challenges and opportunities facing the field of accessibility, particularly as computing becomes ubiquitous. It is argued that a new approach is needed that centres around adaptations (specific, atomic changes) to user interfaces and content in order to improve their accessibility for a wider range of people than targeted by present Assistive Technologies (ATs). Further, the approach must take into consideration the capabilities of people at the human level and facilitate collaboration, in planned and ad-hoc environments. There are two main areas of focus: (1) helping people experiencing minor-to-moderate, transient and potentially-overlapping impairments, as may be brought about by the ageing process and (2) supporting collaboration between people by reasoning about the consequences, from different users perspectives, of the adaptations they may require. A theoretical basis for describing these problems and a reasoning process for the semi-automatic application of adaptations is developed. Impairments caused by the environment in which a device is being used are considered. Adaptations are drawn from other research and industry artefacts. Mechanical testing is carried out on key areas of the reasoning process, demonstrating fitness for purpose. Several fundamental techniques to extend the reasoning process in order to take temporal factors (such as fluctuating user and device capabilities) into account are broadly described. These are proposed to be feasible, though inherently bring compromises (which are defined) in interaction stability and the needs of different actors (user, device, target level of accessibility). This technical work forms the basis of the contribution of one work-package of the Sustaining ICT use to promote autonomy (Sus-IT) project, under the New Dynamics of Ageing (NDA) programme of research in the UK. Test designs for larger-scale assessment of the system with real-world participants are given. The wider Sus-IT project provides social motivations and informed design decisions for this work and is carrying out longitudinal acceptance testing of the processes developed here