728 research outputs found

    Neighborhood effects in wind farm performance: An econometric approach

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    The optimization of turbine density in wind farms entails a trade-off between the usage of scarce, expensive land and power losses through turbine wake effects. A quantification and prediction of the wake effect, however, is challenging because of the complex aerodynamic nature of the interdependencies of turbines. In this paper, we propose a parsimonious data driven econometric wake model that can be used to predict production losses of existing and potential wind parks. Motivated by simple engineering wake models, the predicting variables are wind speed, turbine alignment angle, and distance. By utilizing data from two wind parks in Germany, a significantly better prediction of wake effect losses is attained compared to the standard Jensen model. A scenario analysis reveals that a distance between turbines can be reduced up to three times the rotor size without entailing substantial production losses. In contrast, a suboptimal configuration of turbines with respect to the main wind direction can result in production losses that are five times higher

    Fracture Resistance of Zirconia Oral Implants In Vitro: A Systematic Review and Meta-Analysis

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    Various protocols are available to preclinically assess the fracture resistance of zirconia oral implants. The objective of the present review was to determine the impact of different treatments (dynamic loading, hydrothermal aging) and implant features (e.g., material, design or manufacturing) on the fracture resistance of zirconia implants. An electronic screening of two databases (MEDLINE/Pubmed, Embase) was performed. Investigations including > 5 screw-shaped implants providing information to calculate the bending moment at the time point of static loading to fracture were considered. Data was extracted and meta-analyses were conducted using multilevel mixed-effects generalized linear models (GLMs). The Šidák method was used to correct for multiple testing. The initial search resulted in 1864 articles, and finally 19 investigations loading 731 zirconia implants to fracture were analyzed. In general, fracture resistance was affected by the implant design (1-piece > 2-piece, p = 0.004), material (alumina-toughened zirconia/ATZ > yttria-stabilized tetragonal zirconia polycrystal/Y-TZP, p = 0.002) and abutment preparation (untouched > modified/grinded, p < 0.001). In case of 2-piece implants, the amount of dynamic loading cycles prior to static loading (p < 0.001) or anatomical crown supply (p < 0.001) negatively affected the outcome. No impact was found for hydrothermal aging. Heterogeneous findings of the present review highlight the importance of thoroughly and individually evaluating the fracture resistance of every zirconia implant system prior to market release

    3-D Printed Protective Equipment during COVID-19 Pandemic

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    While the number of coronavirus cases from 2019 continues to grow, hospitals are reporting shortages of personal protective equipment (PPE) for frontline healthcare workers. Furthermore, PPE for the eyes and mouth, such as face shields, allow for additional protection when working with aerosols. 3-D printing enables the easy and rapid production of lightweight plastic frameworks based on open-source data. The practicality and clinical suitability of four face shields printed using a fused deposition modeling printer were examined. The weight, printing time, and required tools for assembly were evaluated. To assess the clinical suitability, each face shield was worn for one hour by 10 clinicians and rated using a visual analogue scale. The filament weight (21-42 g) and printing time (1:40-3:17 h) differed significantly between the four frames. Likewise, the fit, wearing comfort, space for additional PPE, and protection varied between the designs. For clinical suitability, a chosen design should allow sufficient space for goggles and N95 respirators as well as maximum coverage of the facial area. Consequently, two datasets are recommended. For the final selection of the ideal dataset to be used for printing, scalability and economic efficiency need to be carefully balanced with an acceptable degree of protection

    Partial Stochastic Analysis with the Aglink-Cosimo Model: A Methodological Overview

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    Aglink-Cosimo is a recursive-dynamic partial equilibrium model developed and maintained by the OECD and FAO Secretariats as a collaborative effort. The model is primarily used to prepare the OECD-FAO Agricultural Outlook, a yearly publication aiming at providing baseline projections for the main global agricultural commodities over the medium term. This deterministic projections are enhanced by a Partial Stochastic Analysis tool, which allows for the analysis of specific market uncertainties. This is done by producing counterfactual scenarios to the baseline originating from varying yields and macroeconomic variables stochastically. The aim of this report is to propose and evaluate different methods of analysing stochastically important yields and macroeconomic uncertainty drivers. In a first stage, we identify and evaluate the best parametric method to extract unexplained variability, which we consider as uncertainty in the macro and yield drivers. In a second stage, we test parametric and nonparametric methods side by side to simulate ten years of potentially different macroeconomic and yield environments. The results can be summarised as follows. For yields, we find out that a parametric cubic trend method performs best in the first stage and a non-parametric hierarchical copula (Clayton) method is more appropriate in the second stage. For macroeconomic variables, a vector autoregressive model performs best in the first stage, while a non-parametric hierarchical copula (Frank) method is more appropriate in the second stage.JRC.D.4-Economics of Agricultur

    Towards registration of multimodal images of vocal folds based on mutual information.

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    International audienceThis paper deals with mutual information-based registration of multimodal images for laser phonomicrosurgery of the vocal folds. The images to be registered are white light images (white light camera) versus fluorescence images. This work is carried out within the framework of the European project RALP which involves the use of microrobotic system for endoluminal laser phonosurgery. The designed system includes two fiber bundles connected to a high speed camera and one fiber bundle used for fluorescence image. Using the mutual information based registration method, it will be possible to represent the visible information in the fluorescence image and use it in the other image

    Analysis of optical filtering in waveguides with a high index modulation using the extended coupled mode theory by hybridization of a matrix method

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    International audienceIn this paper the authors present an hybrid approach for the analysis of the optical filtering function in corrugated waveguide filters with a high index modulation. This approach is based on the hybridization of the extended couple mode theory (CMT) with the transfer matrix approach. The authors chose to treat the case of high index corrugation because in this case the theory elaborated before is not rigorously applicable. The proposed approach allows the calculation of the reflection coefficient and the full width at half maximum (FWHM) for any index modulation scheme. The hybridization of both methods mentioned above explains the impact and effects of opto-geometric parameters on the reflection coefficient and the bandwidth at mid-height. The theoretical results are verified by experimental measurements realized on Ti:LiNbO3 waveguides with a high index modulation experimentally implemented by engraving using Focused Ion Beam (FIB) process

    Microsensors and image processing for single oocyte qualification: toward multiparametric determination of the best time for fertilization

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    International audienceDuring intracytoplasmic sperm injection (ICSI) attempts, oocytes reaching metaphase II are microinjected. A morphological examination under a microscope is the usual method for determining oocyte maturity. The level of oocyte maturity is based on the meiotic status (Germinal Vesicle, metaphase I and metaphase II) of the oocytes with respect to their increasing maturity. In this letter, we summarize the studies conducted to analyze cytoplasm maturity using various microsystems and image processing. Optical microsystems are used to measure the transmission spectra and refractive index of the oocytes. We compared the transmission spectra measurements to the transmission electron microscopy results. Karhunen-Loeve transform is also used to evaluate the maturity of the oocytes. To summarize, optical analysis techniques are a minimally invasive technology allowing cytoplasm maturity to be assessed. Oocytes should not only be qualified in terms of GV, MI or MII, but also regarding their temporal evolution over the course of these maturation stages. The ultimate aim of this work is to describe the maturation of the oocytes by a trajectory in a multidimensional space and to determine when would be the best time for successful fertilization

    An optimized algorithm of image stitching in the case of a multi-modal probe for monitoring the evolution of scars

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    International audienceWe propose a new system that makes possible to monitor the evolution of scars after the excision of a tumorous dermatosis. The hardware part of this system is composed of a new optical innovative probe with which two types of images can be acquired simultaneously: an anatomic image acquired under a white light and a functional one based on autofluorescence from the protoporphyrin within the cancer cells. For technical reasons related to the maximum size of the area covered by the probe, acquired images are too small to cover the whole scar. That is why a sequence of overlapping images is taken in order to cover the required area. The main goal of this paper is to describe the creation of two panoramic images (anatomic and functional). Fluorescence images do not have enough salient information for matching the images; stitching algorithms are applied over each couple of successive white light images to produce an anatomic panorama of the entire scar. The same transformations obtained from this step are used to register and stitch the functional images. Several experiments have been implemented using different stitching algorithms (SIFT, ASIFT and SURF), with various transformation parameters (angles of rotation, projection, scaling, etc...) and different types of skin images. We present the results of these experiments that propose the best solution. Thus, clinician has two panoramic images superimposed and usable for diagnostic support. A collaborative layer is added to the system to allow sharing panoramas among several practitioners over different places

    Introducing medium-and long-term productivity responses in Aglink-Cosimo

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    This report aims at enhancing the Aglink-Cosimo model by incorporating agricultural productivity growth. It contains a first attempt to develop a measure of the productivity response of agricultural commodities represented in Aglink-Cosimo. In the report we first present how productivity growth is considered at present in the model. Subsequently, we review the literature on how technical progress and price elasticities of yield relate to yield growth. From the literature, we extract a way of capturing endogenously productivity growth. We document the Aglink-Cosimo model changes and focus on some specific cases. Finally, we prepare a scenario analysis on the actual baseline and on an economy with a higher GDP growth rate. The scenario, applied to both cases, studies the effect of a 20% labour price increase on endogenous productivity growth.JRC.D.4-Economics of Agricultur

    Scars collaborative telediagnosis platform using adaptive image flow

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    International audienceTelemedicine has been developed to allow practitioners to remotely connect with patients and with other medical staff.We propose a new system (hardware and software), named DICODERM (COllaborative DIagnosis of DERMatosis), which makes it possible to monitor the evolution of scars after the excision of a tumorous dermatosis (like melanoma). The hardware part of this system is composed of a new optical innovative probe with which two types of images can be acquired simultaneously: anatomic with a white light image and functional with a fluorescence image (using autofluorescence from the protoporphyrin within the cancer cell). The software part is composed of two components: the image stitching component, and the collaborative/adaptive layer component. Our system creates a panoramic view of these scars obtained by stitching a sequence of small images. We conducted experiments for different image stitching algorithms to define the best solution. We also deployed a second component: a collaborative system layer which allows to remotely share images of scars and to adapt these images. We also made the system adaptive to communicate across different client platforms. We conducted experiments to compare the exchange of images with or without adaptation: these tests showed the efficiency of our layer
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