3,406 research outputs found

    Social issues of power harvesting as key enables of WSN in pervasive computing

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    Pervasive systems have gained popularity and open the door to new applications that will improve the quality of life of the users. Additionally, the implementation of such systems over an infrastructure of Wireless Sensor Networks has been proven to be very powerful. To deal with the WSN problems related to the battery of the elements or nodes that constitute the WSN, Power Harvesting techniques arise as good candidates. With PH each node can extract the energy from the surrounding environment. However, this energy source could not be constant, affecting the continuity and quality of the services provided. This behavior can have a negative impact on the user's perception about the system, which could be perceived as unreliable or faulty. In the current paper, some related works regarding pervasive systems within the home environment are referenced to extrapolate the conclusions and problems to the paradigm of Power Harvesting Pervasive Systems from the user perspective. Besides, the paper speculates about the approach and methods to overcome these potential problems and presents the design trends that could be followed.<br/

    Optimization of an Electromagnetic Energy Harvesting Device

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    This paper presents the modeling and optimization of an electromagnetic-based generator for generating power from ambient vibrations. Basic equations describing such generators are presented and the conditions for maximum power generation are described. Two-centimeter scale prototype generators, which consist of magnets suspended on a beam vibrating relative to a coil, have been built and tested. The measured power and modeled results are compared. It is shown that the experimental results confirm the optimization theory

    Photoresist patterned thick-film piezoelectric elements on silicon

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    A fundamental limitation of screen printing is the achievable alignment accuracy and resolution. This paper presents details of a thick-resist process that improves both of these factors. The technique involves exposing/developing a thick resist to form the desired pattern and then filling the features with thick film material using a doctor blading process. Registration accuracy comparable with standard photolithographic processes has been achieved resulting in minimum feature sizes of &lt;50 ?m and a film thickness of 100 ?m. Piezoelectric elements have been successfully poled on a platinised silicon wafer with a measured d 33 value of 60 pCN?1

    Classical Optimizers for Noisy Intermediate-Scale Quantum Devices

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    We present a collection of optimizers tuned for usage on Noisy Intermediate-Scale Quantum (NISQ) devices. Optimizers have a range of applications in quantum computing, including the Variational Quantum Eigensolver (VQE) and Quantum Approximate Optimization (QAOA) algorithms. They are also used for calibration tasks, hyperparameter tuning, in machine learning, etc. We analyze the efficiency and effectiveness of different optimizers in a VQE case study. VQE is a hybrid algorithm, with a classical minimizer step driving the next evaluation on the quantum processor. While most results to date concentrated on tuning the quantum VQE circuit, we show that, in the presence of quantum noise, the classical minimizer step needs to be carefully chosen to obtain correct results. We explore state-of-the-art gradient-free optimizers capable of handling noisy, black-box, cost functions and stress-test them using a quantum circuit simulation environment with noise injection capabilities on individual gates. Our results indicate that specifically tuned optimizers are crucial to obtaining valid science results on NISQ hardware, and will likely remain necessary even for future fault tolerant circuits

    Training health visitors in cognitive behavioural and person-centred approaches for depression in postnatal women as part of a cluster randomised trial and economic evaluation in primary care: the PoNDER trial

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    Aim: This paper aims to describe the training preparation for health visitors who took part in the intervention arm of a cluster randomised controlled trial and economic evaluation of training for health visitors – the POstNatal Depression Economic evaluation and Randomised (the PoNDER) trial. A secondary aim is to make available, by electronic links, the training manuals developed for and used for the cognitive behavioural approach (CBA) and the person-centred approach (PCA) training for the health visitors. The paper is of relevance to health visitors, general practitioners, nurse practitioners, midwives, clinical psychologists, mental health nurses, community psychiatric nurses, counsellors, and service commissioners. Background: The trial clinical outcomes have been published, indicating the pragmatic effectiveness of the package of training for health visitors to identify depressive symptoms and provide a psychologically informed intervention. The training was associated with a reduction in depressive symptoms at six months postnatally among intervention group women and some evidence of a benefit for the intervention group for some of the secondary outcomes at 18 months follow-up. Methods: The two experimental interventions examined in the PoNDER trial built upon promising work on the potential for psychological interventions to help women recover from postnatal depression as an alternative to pharmaceutical interventions and to address the limitations of previous research in the area. Findings: The package of health visitor training comprised the development of clinical skills in assessing postnatal women and identifying depressive symptoms, and the delivery of a CBA or a PCA for eligible women. This was the largest trial a health visitor intervention and of postnatal depression ever conducted. We are aware of no other rigorously performed trial that has published details of an extensively tested training programme for the benefit of health-care professionals and clients

    Digital zero noise extrapolation for quantum error mitigation

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    Zero-noise extrapolation (ZNE) is an increasingly popular technique for mitigating errors in noisy quantum computations without using additional quantum resources. We review the fundamentals of ZNE and propose several improvements to noise scaling and extrapolation, the two key components in the technique. We introduce unitary folding and parameterized noise scaling. These are digital noise scaling frameworks, i.e. one can apply them using only gate-level access common to most quantum instruction sets. We also study different extrapolation methods, including a new adaptive protocol that uses a statistical inference framework. Benchmarks of our techniques show error reductions of 18X to 24X over non-mitigated circuits and demonstrate ZNE effectiveness at larger qubit numbers than have been tested previously. In addition to presenting new results, this work is a self-contained introduction to the practical use of ZNE by quantum programmers.Comment: 11 pages, 7 figure

    Strong Coupling Theory for Interacting Lattice Models

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    We develop a strong coupling approach for a general lattice problem. We argue that this strong coupling perspective represents the natural framework for a generalization of the dynamical mean field theory (DMFT). The main result of this analysis is twofold: 1) It provides the tools for a unified treatment of any non-local contribution to the Hamiltonian. Within our scheme, non-local terms such as hopping terms, spin-spin interactions, or non-local Coulomb interactions are treated on equal footing. 2) By performing a detailed strong-coupling analysis of a generalized lattice problem, we establish the basis for possible clean and systematic extensions beyond DMFT. To this end, we study the problem using three different perspectives. First, we develop a generalized expansion around the atomic limit in terms of the coupling constants for the non-local contributions to the Hamiltonian. By analyzing the diagrammatics associated with this expansion, we establish the equations for a generalized dynamical mean-field theory (G-DMFT). Second, we formulate the theory in terms of a generalized strong coupling version of the Baym-Kadanoff functional. Third, following Pairault, Senechal, and Tremblay, we present our scheme in the language of a perturbation theory for canonical fermionic and bosonic fields and we establish the interpretation of various strong coupling quantities within a standard perturbative picture.Comment: Revised Version, 17 pages, 5 figure

    Ethanol Marketing and Input Procurement Practices of U.S. Ethanol Producers: 2008 Survey Results

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    A mail survey was used to collect information about input procurement and ethanol and co-product marketing practices from 60 U.S. ethanol production facilities. Data were used to answer questions about the conduct or behavior of ethanol producers. It was anticipated that firm conduct or behavior would be fairly homogeneous because the ethanol industry was in Stage II of the industry life-cycle, and societal support for ethanol production resulted in large volumes of publicly available information about technology and markets. Age of facility, size of facility, and type of ownership jointly explained a limited number of differences in responses across ethanol facilities, thus supporting the concept of fairly homogeneous conduct or behavior.entry timing, ethanol, farmer-owned cooperatives, industry life-cycle, Agribusiness, Resource /Energy Economics and Policy, Q11, Q42,
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