Power-conserving routing of ad hoc mobile wireless networks based on entropy-constrained algorithms

This paper presents an approach to power-conserving routing of ad hoc mobile wireless networks. This approach relies on entropy-constrained routing algorithms, which were developed by utilizing the information-theoretic concept of the entropy to gradually reduce the uncertainty associated with route discovery through a deterministic annealing process. Entropy-constrained routing algorithms were tested using a single performance metric related to the distance between the nodes and to the power consumption associated with packet transmission. This paper also expands the versatility of entropy-constrained routing algorithms by making them capable of discovering routes based on multiple performance metrics. In this study, the second performance metric employed for route discovery relied on the power availability in the nodes of the network. The proposed routing approach was evaluated in terms of the power consumption associated with the routing of packets over an ad hoc mobile network in a variety of operating conditions.     

intGuide: A platform for context-aware services featuring augmented-reality, based on the outcome of European Research Projects

As people become increasingly acquainted with information technology, they demand continuous availability of services related to their work or leisure. The era of ubiquitous computing announced long ago is currently turning into an everyday reality at an ever-increasing pace. Alongside the evolution of ubiquitous and nomadic computing, the need of people to access vast amounts of information in a comprehensive and efficient way gives rise to the areas of information visualization and augmented-reality. Such technologies allow for the comprehensive presentation of visual information equally addressing the needs of different categories of people.

In the past 5 years, we have been active in a set of European Research Projects addressing the above-mentioned research directions, with the long-term goal to develop a software platform that will enable context-aware services deploying advanced visualization technology in a series of application domains, such as cultural heritage dissemination, interactive television and retail industry. The multitude of the application domains addressed, as well as the multidisciplinary expertise necessary to create a generic platform was successfully addressed in complementary research activities. In this paper, we present the idea of a platform for context-aware services by exploiting advanced visualization technology and subsequently we briefly review the research projects that delivered valuable pieces in the overall puzzle. Emphasis is put on the practical issues of the implementation and deployment in different application scenarios.     

Brief an einen Kollegen unmittelbar vor seiner Emeritierung

Ohne Zusammenfassung     

Quantifying motion in video recordings of neonatal seizures by robust motion trackers based on block motion models

This paper introduces a methodology for the development of robust motion trackers for video based on block motion models. According to this methodology, the motion of a site between two successive frames is estimated by minimizing an error function defined in terms of the intensities at these frames. The proposed methodology is used to develop robust motion trackers that rely on fractional block motion models. The motion trackers developed in this paper are utilized to extract motor activity signals from video recordings of neonatal seizures. The experimental results reveal that the proposed motion trackers are more accurate and reliable than existing motion tracking methods relying on pure translation and affine block motion models.     

Improving the accuracy and reliability of motion tracking methods used for extracting temporal motor activity signals from video recordings of neonatal seizures

This paper presents an approach for improving the accuracy and reliability of motion tracking methods developed for video based on block motion models. This approach estimates the displacement of a block of pixels between two successive frames by minimizing an error function defined in terms of the pixel intensities at these frames. The minimization problem is made analytically tractable by approximating the error function using a second-order Taylor expansion. The improved reliability of the proposed method is illustrated by its application in the extraction of temporal motor activity signals from video recordings of neonatal seizures.     

Nanodevices: Location of Biomarkers and Reagents within Agarose Beads of a Programmable Nano‐bio‐chip (Small 5/2011)

The slow development of cost‐effective medical microdevices with strong analytical performance characteristics is due to a lack of selective and efficient analyte capture and signaling. The recently developed programmable nano‐bio‐chip (PNBC) is a flexible detection device with analytical behavior rivaling established macroscopic methods. The PNBC system employs ≈300 μm‐diameter bead sensors composed of agarose “nanonets” that populate a microelectromechanical support structure with integrated microfluidic elements. The beads are an efficient and selective protein‐capture medium suitable for the analysis of complex fluid samples. Microscopy and computational studies probe the 3D interior of the beads. The relative contributions that the capture and detection of moieties, analyte size, and bead porosity make to signal distribution and intensity are reported. Agarose pore sizes ranging from 45 to 620 nm are examined and those near 140 nm provide optimal transport characteristics for rapid (<15 min) tests. The system exhibits efficient (99.5%) detection of bead‐bound analyte along with low (≈2%) nonspecific immobilization of the detection probe for carcinoembryonic antigen assay. Furthermore, the role analyte dimensions play in signal distribution is explored, and enhanced methods for assay building that consider the unique features of biomarker size are offered.     

Double helical laser beams based on interfering first-order Bessel beams

We demonstrate the generation of a nondiffracting double helical beam using axicons and ±1 vortex phase plates in a common-path interferometric system. Using linear diffraction theory, a simple analytical expression describing beam propagation is shown to agree with both experiments and Fresnel-diffraction-based simulations. Experiments are performed using continuous laser light in addition to ultrafast pulses, demonstrating that the common-path arrangement and the diffraction theory work equally well for both cases.     

Unbalanced voltage faults: the impact on structural loads of doubly fed asynchronous generator wind turbines

This paper investigates the impact that unbalanced voltage faults have on wind turbine structural loads. In such cases, electromagnetic torque oscillations occur at two times the supply voltage frequency. The objectives of this work are to quantify wind turbine structural loads induced by unbalanced voltage faults relative to those during normal operation; and to evaluate the potential for reducing structural loads with the control of the generator. The method applied is integrated dynamic analysis. Namely, dynamic analysis with models that consider the most important aeroelastic, electrical, and control dynamics in an integrated simulation environment based on an aeroelastic code (HAWC2) and software for control design (Matlab/Simulink). In the present analysis, 1 Hz equivalent loads are used to compare fatigue loads, whereas maximum–minimum values are used to compare extreme loads. A control concept based on resonant filters demonstrates reduction of the structural loads (shaft torsion and tower top side‐to‐side moment) induced by an unbalanced voltage fault.Copyright © 2013 John Wiley & Sons, Ltd.     

LED pulse distortion in single-mode fibres near the wavelength of zero dispersion

We show that the broadening of LED pulses in single-mode fibres due to higher-order dispersive effects, which are significant near the wavelength of zero dispersion, is considerably less than that predicted on the basis of RMS theory.