272 research outputs found

    Does Information Transparency Decrease Coordination Failure?

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    This study experimentally tests the effect of information transparency on the probability of coordination failure in global games with finite signals. Prior theory has shown that in global games with unique equilibrium, the effect of information transparency is ambiguous. We find that in global games where the signal space is finite, increased transparency has two effects. First, increasing the level of transparency usually destroys uniqueness and precipitates multiple equilibria, so that the effect of transparency on coordination depends crucially upon which equilibrium is actually attained. Second, the level of transparency determines which of these equilibria is risk dominant. We find that increased transparency facilitates coordination only if it switches the risk-dominant equilibrium from the secure equilibrium to the efficient equilibrium. When the converse is true, improved transparency can be dysfunctional because it increases the probability of coordination failure.

    Integrating Algaculture into Small Wastewater Treatment Plants: Process Flow Options and Life Cycle Impacts

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    Algaculture has the potential to be a sustainable option for nutrient removal at wastewater treatment plants. The purpose of this study was to compare the environmental impacts of three likely algaculture integration strategies to a conventional nutrient removal strategy. Process modeling was used to determine life cycle inventory data and a comparative life cycle assessment was used to determine environmental impacts. Treatment scenarios included a base case treatment plant without nutrient removal, a plant with conventional nutrient removal, and three other cases with algal unit processes placed at the head of the plant, in a side stream, and at the end of the plant, respectively. Impact categories included eutrophication, global warming, ecotoxicity, and primary energy demand. Integrating algaculture prior to activated sludge proved to be most beneficial of the scenarios considered for all impact categories; however, this scenario would also require primary sedimentation and impacts of that unit process should be considered for implementation of such a system

    Non-stationary temporal characterization of the temperature profile of a soil exposed to frost in south-eastern Canada

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    The objective of this work was to compare time and frequency fluctuations of air and soil temperatures (2-, 5-, 10-, 20- and 50-cm below the soil surface) using the continuous wavelet transform, with a particular emphasis on the daily cycle. The analysis of wavelet power spectra and cross power spectra provided detailed non-stationary accounts with respect to frequencies (or periods) and to time of the structure of the data and also of the relationships that exist between time series. For this particular application to the temperature profile of a soil exposed to frost, both the air temperature and the 2-cm depth soil temperature time series exhibited a dominant power peak at 1-d periodicity, prominent from spring to autumn. This feature was gradually damped as it propagated deeper into the soil and was weak for the 20-cm depth. Influence of the incoming solar radiation was also revealed in the wavelet power spectra analysis by a weaker intensity of the 1-d peak. The principal divergence between air and soil temperatures, besides damping, occurred in winter from the latent heat release associated to the freezing of the soil water and the insulation effect of snowpack that cease the dependence of the soil temperature to the air temperature. Attenuation and phase-shifting of the 1-d periodicity could be quantified through scale-averaged power spectra and time-lag estimations. Air temperature variance was only partly transferred to the 2-cm soil temperature time series and much less so to the 20-cm soil depth

    Can a multi-model approach improve hydrological ensemble forecasting? A study on 29 French catchments using 16 hydrological model structures

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    An operational hydrological ensemble forecasting system based on a meteorological ensemble prediction system (M-EPS) coupled with a hydrological model searches to capture the uncertainties associated with the meteorological prediction to better predict river flows. However, the structure of the hydrological model is also an important source of uncertainty that has to be taken into account. This study aims at evaluating and comparing the performance and the reliability of different types of hydrological ensemble prediction systems (H-EPS), when ensemble weather forecasts are combined with a multi-model approach. The study is based on 29 catchments in France and 16 lumped hydrological model structures, driven by the weather forecasts from the European centre for medium-range weather forecasts (ECMWF). Results show that the ensemble predictions produced by a combination of several hydrological model structures and meteorological ensembles have higher skill and reliability than ensemble predictions given either by one single hydrological model fed by weather ensemble predictions or by several hydrological models and a deterministic meteorological forecast

    Global sensitivity analysis in environmental water quality modelling: Where do we stand?

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    Global sensitivity analysis (GSA) is a valuable tool to support the use of mathematical models for environmental systems. During the last years the water quality modelling field has embraced the use of GSA. Environmental water quality modellers have tried to transfer the knowledge and experience acquired in other disciplines. The main objective of this paper is to provide an informed problem statement of the issues surrounding GSA applications in the environmental water quality modelling field. Specifically, this paper aims at identifying, for each GSA method, the potential use, the critical issues to be solved and the limits identified in a comprehensive literature review. The paper shows that the GSA methods are not mostly applied by using the numerical settings as suggested in the literature for other application fields. However, some authors have emphasized that the modeller must take care in employing such \u201cdefault\u201d numerical settings because,for complex water quality models, different GSA methods have been shown to provide different results depending on the settings. Quantitative convergence analysis has been identified as a key element for GSA quality control that merits further investigations for GSA application in the environmental water quality modelling field

    Efficient treatment of climate data uncertainty in ensemble Kalman filter (EnKF) based on an existing historical climate ensemble dataset

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    The final publication is available at Elsevier via https://doi.org/10.1016/j.jhydrol.2018.11.047. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Successful data assimilation depends on the accurate estimation of forcing data uncertainty. Forcing data uncertainty is typically estimated based on statistical error models. In practice, the hyper-parameters of statistical error models are often estimated by a trial-and-error tuning process, requiring significant analyst and computational time. To improve the efficiency of forcing data uncertainty estimation, this study proposes the direct use of existing ensemble climate products to represent climate data uncertainty in the ensemble Kalman filter (EnKF) of flow forecasting. Specifically, the Newman et al. (2015) dataset (N15 for short), covering the contiguous United States, northern Mexico, and southern Canada, is used here to generate the precipitation and temperature ensemble in the EnKF application. This study for the first time compares the N15 generated climate ensemble with the carefully tuned hyper-parameters generated climate ensemble in a real flow forecasting framework. The forecast performance comparison of 20 Québec catchments shows that the N15 generated climate ensemble yields improved or similar deterministic and probabilistic flow forecasts relative to the carefully tuned hyper-parameters generated climate ensemble. Improvements are most evident for short lead times (i.e., 1–3 days) when the influence of data assimilation dominates. However, the analysis and computational time required to use N15 is much less compared to the typical trial-and-error hyper-parameter tuning process.Natural Sciences and Engineering Research Council [NETGP 451456

    Validating simulation environments for automated driving systems using 3d object comparison metric

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    One of the main challenges for the introduction of Automated Driving Systems (ADSs) is their verification and validation (V&V). Simulation based testing has been widely accepted as an essential aspect of the ADS V&V processes. Simulations are especially useful when exposing the ADS to challenging driving scenarios, as they offer a safe and efficient alternative to real world testing. It is thus suggested that evidence for the safety case for an ADS will include results from both simulation and real-world testing. However, for simulation results to be trusted as part of the safety case of an ADS for its safety assurance, it is essential to prove that the simulation results are representative of the real world, thus validating the simulation platform itself. In this paper, we propose a novel methodology for validating the simulation environments focusing on comparing point cloud data from real lidar sensor and a simulated lidar sensor model. A 3D object dissimilarity metric is proposed to compare between the two maps (real and simulated), to quantify how accurate the simulation is. This metric is tested on collected lidar point cloud data and the simulated point cloud generated in the simulated environment

    Circadian Cycles of Gene Expression in the Coral, Acropora millepora

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    Background: Circadian rhythms regulate many physiological, behavioral and reproductive processes. These rhythms are often controlled by light, and daily cycles of solar illumination entrain many clock regulated processes. In scleractinian corals a number of different processes and behaviors are associated with specific periods of solar illumination or nonillumination—for example, skeletal deposition, feeding and both brooding and broadcast spawning. Methodology/Principal Findings: We have undertaken an analysis of diurnal expression of the whole transcriptome and more focused studies on a number of candidate circadian genes in the coral Acropora millepora using deep RNA sequencing and quantitative PCR. Many examples of diurnal cycles of RNA abundance were identified, some of which are light responsive and damped quickly under constant darkness, for example, cryptochrome 1 and timeless, but others that continue to cycle in a robust manner when kept in constant darkness, for example, clock, cryptochrome 2, cycle and eyes absent, indicating that their transcription is regulated by an endogenous clock entrained to the light-dark cycle. Many other biological processes that varied between day and night were also identified by a clustering analysis of gene ontology annotations. Conclusions/Significance: Corals exhibit diurnal patterns of gene expression that may participate in the regulation of circadian biological processes. Rhythmic cycles of gene expression occur under constant darkness in both populations o

    Status report on emerging photovoltaics

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    \ua9 2023 Society of Photo-Optical Instrumentation Engineers (SPIE).This report provides a snapshot of emerging photovoltaic (PV) technologies. It consists of concise contributions from experts in a wide range of fields including silicon, thin film, III-V, perovskite, organic, and dye-sensitized PVs. Strategies for exceeding the detailed balance limit and for light managing are presented, followed by a section detailing key applications and commercialization pathways. A section on sustainability then discusses the need for minimization of the environmental footprint in PV manufacturing and recycling. The report concludes with a perspective based on broad survey questions presented to the contributing authors regarding the needs and future evolution of PV

    Complete breeding failures in ivory gull following unusual rainy storms in North Greenland

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    Natural catastrophic events such as heavy rainfall and windstorms may induce drastic decreases in breeding success of animal populations. We report the impacts of summer rainfalls on the reproductive success of ivory gull (Pagophila eburnea) in north-east Greenland. On two occasions, at Amdrup Land in July 2009 and at Station Nord in July 2011, we observed massive ivory gull breeding failures following violent rainfall and windstorms that hit the colonies. In each colony, all of the breeding birds abandoned their eggs or chicks during the storm. Juvenile mortality was close to 100% at Amdrup Land in 2009 and 100% at Station Nord in 2011. Our results show that strong winds associated with heavy rain directly affected the reproductive success of some Arctic bird species. Such extreme weather events may become more common with climate change and represent a new potential factor affecting ivory gull breeding success in the High Arctic
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