653 research outputs found

    High-temperature molten salt thermal energy storage systems

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    The results of comparative screening studies of candidate molten carbonate salts as phase change materials (PCM) for advanced solar thermal energy storage applications at 540 to 870 C (1004 to 1600 F) and steam Rankine electric generation at 400 to 540 C (752 to 1004 F) are presented. Alkali carbonates are attractive as latent heat storage materials because of their relatively high storage capacity and thermal conductivity, low corrosivity, moderate cost, and safe and simple handling requirements. Salts were tested in 0.1 kWhr lab scale modules and evaluated on the basis of discharge heat flux, solidification temperature range, thermal cycling stability, and compatibility with containment materials. The feasibility of using a distributed network of high conductivity material to increase the heat flux through the layer of solidified salt was evaluated. The thermal performance of an 8 kWhr thermal energy storage (TES) module containing LiKCO3 remained very stable throughout 5650 hours and 130 charge/discharge cycles at 480 to 535 C (896 to 995 F). A TES utilization concept of an electrical generation peaking subsystem composed of a multistage condensing steam turbine and a TES subsystem with a separate power conversion loop was defined. Conceptual designs for a 100 MW sub e TES peaking system providing steam at 316 C, 427 C, and 454 C (600 F, 800 F, and 850 F) at 3.79 million Pa (550 psia) were developed and evaluated. Areas requiring further investigation have also been identified

    Typification of names in genus Hieracium based on original herbarium material of Alexis Jordan and Alexandre Boreau

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    181 names of Hieracium species going back to original herbarium material of Alexis Jordan or Alexandre Boreau are lectotypified, 27 are neotypified. The study is based on herbarium specimens of the Université Catholique de Lyon (LY) and Ville d’Angers (ANG), Martrin-Donos’s herbarium at the Institut Botanique de Montpellier (MPUTarn) and Arvet-Touvet’s herbarium at the Musée d’Histoire Naturelle de Grenoble (GRM-AT). The type specimens are illustrated by photographs of the entire herbarium sheets with some detail views of flower heads and leaves. Usual nomenclatural synonyms are given for each taxon

    Transformed Minds

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    In this brief collection of essays, professors who teach in the Department of History and Government at Cedarville University explore the biblical foundation for the academic disciplines unique to their Department. The Excerpt (above) contains the full text of the book.https://digitalcommons.cedarville.edu/faculty_books/1182/thumbnail.jp

    Born-Infeld Theory and Stringy Causality

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    Fluctuations around a non-trivial solution of Born-Infeld theory have a limiting speed given not by the Einstein metric but the Boillat metric. The Boillat metric is S-duality invariant and conformal to the open string metric. It also governs the propagation of scalars and spinors in Born-Infeld theory. We discuss the potential clash between causality determined by the closed string and open string light cones and find that the latter never lie outside the former. Both cones touch along the principal null directions of the background Born-Infeld field. We consider black hole solutions in situations in which the distinction between bulk and brane is not sharp such as space filling branes and find that the location of the event horizon and the thermodynamic properties do not depend on whether one uses the closed or open string metric. Analogous statements hold in the more general context of non-linear electrodynamics or effective quantum-corrected metrics. We show how Born-Infeld action to second order might be obtained from higher-curvature gravity in Kaluza-Klein theory. Finally we point out some intriguing analogies with Einstein-Schr\"odinger theory.Comment: 31 pages, 4 figures, LaTex; Some comments and references adde

    Investigation of four-year chemical composition and organic aerosol sources of submicron particles at the ATOLL site in northern France

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    This study presents the first long-term online measurements of submicron (PM1) particles at the ATOLL (ATmospheric Observations in liLLe) platform, in northern France. The ongoing measurements using an Aerosol Chemical Speciation Monitor (ACSM) started at the end of 2016 and the analysis presented here spans through December 2020. At this site, the mean PM1 concentration is 10.6 μg m-3, dominated by organic aerosols (OA, 42.3%) and followed by nitrate (28.9%), ammonium (12.3%), sulfate (8.6%), and black carbon (BC, 8.0%). Large seasonal variations of PM1 concentrations are observed, with high concentrations during cold seasons, associated with pollution episodes (e.g. over 100 μg m-3 in January 2017). To study OA origins over this multiannual dataset we performed source apportionment analysis using rolling positive matrix factorization (PMF), yielding two primary OA factors, a traffic-related hydrocarbon-like OA (HOA) and biomass-burning OA (BBOA), and two oxygenated OA (OOA) factors. HOA showed a homogeneous contribution to OA throughout the seasons (11.8%), while BBOA varied from 8.1% (summer) to 18.5% (winter), the latter associated with residential wood combustion. The OOA factors were distinguished between their less and more oxidized fractions (LO-OOA and MO-OOA, on average contributing 32% and 42%, respectively). During winter, LO-OOA is identified as aged biomass burning, so at least half of OA is associated with wood combustion during this season. Furthermore, ammonium nitrate is also a predominant aerosol component during cold-weather pollution episodes - associated with fertilizer usage and traffic emissions. This study provides a comprehensive analysis of submicron aerosol sources at the recently established ATOLL site in northern France from multiannual observations, depicting a complex interaction between anthropogenic and natural sources, leading to different mechanisms of air quality degradation in the region across different seasons

    Linearisation Instabilities of the Massive Nonsymmetric Gravitational Theory

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    The massive nonsymmetric gravitational theory is shown to posses a linearisation instability at purely GR field configurations, disallowing the use of the linear approximation in these situations. It is also shown that arbitrarily small antisymmetric sector Cauchy data leads to singular evolution unless an ad hoc condition is imposed on the initial data hypersurface.Comment: 14 pages, IOP style for submission to CQG. Minor changes and additional background material adde

    Falls in ambulatory non-demented patients with Parkinson's disease

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    This study aimed at determining the prevalence of falling in PD patients, to assess generic and disease-specific clinical and pharmacological factors, relationship with health-related quality of life (HR-QoL) and changes in falls from OFF to ON in patients with motor fluctuations. Six-hundred and eighty-three PD patients of the COPARK survey were evaluated (11 had missing data and were excluded from the analysis). Patients with falls were identified as those with a UPDRS Item 13 ¡Ý 1 in the ON condition. All patients were assessed in a standardized manner [demographics, treatments, Unified PD Rating Scale (UPDRS), Hospital Anxiety and Depression Scale, Pittsburg questionnaire and HR-QoL scales (SF36, PDQ39)]. Falling was reported by 108/672 (16 %) PD patients during the ON state and prevalence increased according to PD severity, from 5 % in Hoehn and Yahr stage 1-60 % in stage 4. Falling was significantly related to lower HR-QoL. Falling correlated with (1) generic factors such as female gender, age at the end of academic studies and diuretics consumption, (2) motor PD-specific factors including disease severity, frozen gait, difficulties when arising from a chair, dyskinesia and higher levodopa daily equivalent dose and (3) non-motor PD-specific factors such as orthostatic hypotension and hallucinations. Falling was more frequent in OFF than in ON in 48/74 (64 %) patients with motor fluctuations and remained unchanged in 27 patients (36 %). In summary, falling affected a significant proportion of PD patients, especially in advanced stages. It was associated with a variety of generic and PD-specific factors and was related to reduced HR-QoL.Fil: Rascol, Olivier. NS-Park Network; Francia. Université Paul Sabatier; Francia. Inserm; FranciaFil: Pérez Lloret, Santiago. Université Paul Sabatier; Francia. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Damier, Philippe. Hôpital Laënnec; Francia. NS-Park Network; Francia. Inserm; FranciaFil: Delval, Arnaud. Seul Centre Hospitalier Universitaire; FranciaFil: Derkinderen, Pascal. Hôpital Laënnec; FranciaFil: Destée, Alain. NS-Park Network; Francia. Inserm; Francia. Seul Centre Hospitalier Universitaire; FranciaFil: Meissner, Wassilios G.. Universite de Bordeaux; Francia. Institut des Maladies Neurodégénératives; Francia. Centre Hospitalier Universitaire de Bordeaux; FranciaFil: Tison, Francois. Universite de Bordeaux; Francia. Centre Hospitalier Universitaire de Bordeaux; Francia. Institut des Maladies Neurodégénératives; Francia. NS-Park Network; FranciaFil: Negre Pages, Laurence. Inserm; Francia. NS-Park Network; Franci
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