19,601 research outputs found

    Numerical modeling of shape and topology optimisation of a piezoelectric cantilever beam in an energy-harvesting sensor

    Get PDF
    Piezoelectric materials are excellent transducers for converting mechanical energy from the environment for use as electrical energy. The conversion of mechanical energy to electrical energy is a key component in the development of self-powered devices, especially enabling technology for wireless sensor networks. This paper proposes an alternative method for predicting the power output of a bimorph cantilever beam using a finite-element method for both static and dynamic frequency analyses. A novel approach is presented for optimising the cantilever beam, by which the power density is maximised and the structural volume is minimised simultaneously. A two-stage optimisation is performed, i.e., a shape optimisation and then a “topology” hole opening optimisation

    Evaluation of the Immigrant Citizens Survey (ICS)

    Get PDF
    This evaluation undertakes a critical appraisal of the "Immigrant Citizens Survey (ICS)". The survey was funded under the European Integration Fund and jointly coordinated by the King Baudouin Foundation (KBF) and the Migration Policy Group (MPG). The survey was implemented in cooperation with research, polling and launch partners in the 7 countries covered by the survey. The survey was implemented in 2011 and 2012 and launched in May 2012

    CAutoCSD-evolutionary search and optimisation enabled computer automated control system design

    Get PDF
    This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of 'Computer-Aided Control System Design' (CACSD) to the novel 'Computer-Automated Control System Design' (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency-domains. Such performance-prioritised unification is aimed to relieve practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-committing to the adopted scheme. With the recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytically and practically, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, meets multiple objectives in designing an LTI controller for a non-minimum phase plant and offers a high-performing LTI controller network for a nonlinear chemical process

    Sampling and Surveying Hard-to-Reach Populations for Demographic Research

    Get PDF
    Because household-based survey designs are notoriously ineffective in studying hard-to-reach groups such as irregular migrants, these groups, however numerically large they may be, are rarely represented in demographic analyses. In this paper, we report on the application of a workplace-based stratified probability sampling design, response rate, and item-specific refusals in a recent study of irregular female migrants from Tajikistan, Kyrgyzstan, and Uzbekistan working in bazaars, eateries, and small retail outlets in Moscow, Russia. We argue that workplace-based survey, while not flawless, provides a uniquely feasible and cost-effective tool for studying irregular migrants and other marginalized groups.Central Asia, migration, Russia, sampling, survey methodology

    Bilateral Filter: Graph Spectral Interpretation and Extensions

    Full text link
    In this paper we study the bilateral filter proposed by Tomasi and Manduchi, as a spectral domain transform defined on a weighted graph. The nodes of this graph represent the pixels in the image and a graph signal defined on the nodes represents the intensity values. Edge weights in the graph correspond to the bilateral filter coefficients and hence are data adaptive. Spectrum of a graph is defined in terms of the eigenvalues and eigenvectors of the graph Laplacian matrix. We use this spectral interpretation to generalize the bilateral filter and propose more flexible and application specific spectral designs of bilateral-like filters. We show that these spectral filters can be implemented with k-iterative bilateral filtering operations and do not require expensive diagonalization of the Laplacian matrix

    Dispensing with channel estimation: differentially modulated cooperative wireless communications

    No full text
    As a benefit of bypassing the potentially excessive complexity and yet inaccurate channel estimation, differentially encoded modulation in conjunction with low-complexity noncoherent detection constitutes a viable candidate for user-cooperative systems, where estimating all the links by the relays is unrealistic. In order to stimulate further research on differentially modulated cooperative systems, a number of fundamental challenges encountered in their practical implementations are addressed, including the time-variant-channel-induced performance erosion, flexible cooperative protocol designs, resource allocation as well as its high-spectral-efficiency transceiver design. Our investigations demonstrate the quantitative benefits of cooperative wireless networks both from a pure capacity perspective as well as from a practical system design perspective

    The Road From Classical to Quantum Codes: A Hashing Bound Approaching Design Procedure

    Full text link
    Powerful Quantum Error Correction Codes (QECCs) are required for stabilizing and protecting fragile qubits against the undesirable effects of quantum decoherence. Similar to classical codes, hashing bound approaching QECCs may be designed by exploiting a concatenated code structure, which invokes iterative decoding. Therefore, in this paper we provide an extensive step-by-step tutorial for designing EXtrinsic Information Transfer (EXIT) chart aided concatenated quantum codes based on the underlying quantum-to-classical isomorphism. These design lessons are then exemplified in the context of our proposed Quantum Irregular Convolutional Code (QIRCC), which constitutes the outer component of a concatenated quantum code. The proposed QIRCC can be dynamically adapted to match any given inner code using EXIT charts, hence achieving a performance close to the hashing bound. It is demonstrated that our QIRCC-based optimized design is capable of operating within 0.4 dB of the noise limit
    corecore