6,512 research outputs found

    Weighted estimates for solutions of the ∂\partial -equation for lineally convex domains of finite type and applications to weighted bergman projections

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    In this paper we obtain sharp weighted estimates for solutions of the ∂\partial-equation in a lineally convex domains of finite type. Precisely we obtain estimates in spaces of the form L p ({\Omega},δ\delta γ\gamma), δ\delta being the distance to the boundary, with gain on the index p and the exponent γ\gamma. These estimates allow us to extend the L p ({\Omega},δ\delta γ\gamma) and lipschitz regularity results for weighted Bergman projection obtained in [CDM14b] for convex domains to more general weights

    A Review of Energy Models. No. 3 (Special Issue on Soviet Models)

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    The experience of the USSR in the field of energy systems development modeling reveals certain patterns and principles that influence the structure and use of energy models, principally: -- The need to use mainly optimization models since, for planning purposes, optimal solutions must be found; -- The need to coordinate individual models in order to obtain the country's objectives; -- The existing organizational structure of planning which must be taken into account; -- The dependence of models on time aspects of planning (annual, 5-year, 15-year); -- The elaboration of corresponding methods for providing necessary input data. This has required the development of a special concept for optimizing energy systems development with the use of mathematical models. It is based on consideration of the energy industries of the country as complex with a hierarchical structure of energy systems of various territorial and branch levels. At the same time, the differentiation of aims at different times during the planning period have been taken into account. This concept is given here in its existing state (it is continuously developed and perfected) for better understanding of the energy models described. In particular, we show the role of the system of models for optimization of the energy supply system as a whole, and that of more detailed branch models (oil, gas, coal, electricity production systems). For optimal energy strategy evaluation, the most important models are those used on the highest levels of the energy systems hierarchy, i.e. the general (aggregate) energy systems of the country and of economic regions, and branch energy systems. Only these models are described here; models used on lower levels for solving some technical problems are far more diverse and numerous, and it is impossible to consider them all in a single review

    A Review of Energy Models No.4 - July 1978

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    This review is the fourth in the IIASA series A REVIEW OF ENERGY MODELS (RR-74-10, No. 1 of May 1974 as revised in September 1976; RR-75-30, No. 2 of July 1975; and RR-77-13, No. 3, Special Issue of Soviet Models), which aims at wider diffusion of energy modeling work in progress at other institutions. Fourteen models are described in this issue and again classified in terms of substance and geographical applicability with further subdivision into groups corresponding to model user requirements: the majority of the models focus on the energy problem; they are mostly national ones involving either one or several kinds of fuel; six other models, both international and national, combine energy and overall economic aspects; they may be of particular interest for a more global consideration of energy problems

    Continuous nonlinear eigenvalue solver with applications to the design of electro/magnetorheological sandwich structures

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    International audienceSmart sandwich structures comprising an electro-or a magnetorheo-logical material have the potential to attenuate vibration over a wide range of frequencies. The analysis of their vibration behaviour with respect to the continuous variation of the field intensity is thus a major challenge for research and industry to maximize damping treatments. The numerical higher order homotopy method we propose models the effects of a continuous variation of the field intensity on resonant frequencies and loss factors by means of Taylor expansions. Comparisons between our continuous approach and the classical incremental method are proposed for state of the art sandwich beams and plate structures comprising ER/MR fluids to highlight the benefits of our continuous methods in terms of maximal damping determination

    Mate guarding and paternity in mandrills: factors influencing alpha male monopoly

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    We used long-term data on mate guarding and paternity in mandrills, Mandrillus sphinx, (1) to examine cycle day and cycle selection by males; (2) to examine associations between male rank, periovulatory mate guarding and paternity outcome; (3) to test the predictions of the priority-of-access model; and (4) to investigate factors influencing the ability of alpha males to monopolize females. Males mate-guarded on periovulatory days more than on other receptive days, and during conceptive cycles more than during nonconceptive cycles. Both periovulatory mate guarding and paternity outcome correlated significantly with male rank. Alpha males accounted for 94% of periovulatory mate guarding and 69% of paternity, confirming the existence of extremely high reproductive skew in this highly sexually dimorphic species. The fit of the observed distributions of mate guarding and paternity to predictions from the priority-of-access model was good, but in both cases the alpha males accounted for a greater proportion of reproduction than predicted. Mate guarding was a good predictor of paternity, but consistently overestimated the reproductive success of the alpha male. Splitting data into group-years revealed that the percentage of mate guarding by the alpha male decreased with increasing numbers of adult males, and the percentage of paternity decreased with increasing numbers of reproductive males (all postpubertal males). Furthermore, mate guarding became less effective as the number of reproductive males increased. We attribute this to the fact that only males aged 8 years or more mate-guarded, but that all males aged at least 3.8 years may sneak copulations, reducing the effectiveness of mate guarding and therefore reducing paternity concentration in the alpha male

    Flor yeast metabolism in a model system similar to cellar ageing of the French "Vin Jaune": Evolution of some by-products, nitrogen compounds and polysaccharides

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    French flor-sherry wine "Vin Jaune" (Jura region) made from Savagnin grapes is aged under a film of Saccharomyces cerevisiae flor yeasts for 6 years and three months. During this ageing, velum develops and falls corresponding to yeast multiplication and autolysis, In a model system using glass receptacles ("Fioles de Roux") containing sterilised Savagnin wine inoculated with a pure culture of S. cerevisiae flor yeast, the evolution of velum was studied for 15 weeks. At the same time, nitrogen compounds (amino acids, peptides and proteins) and neutral polysaccharides were quantified in relation to glycerol, volatile acidity and acetaldehyde, Compounds such as glycerol, acetic acid and amino acids including proline are consumed by the flor yeasts whereas other compounds such as peptides and neutral polysaccharides are released. At the same time, yeasts produce other compounds, namely acetaldehyde

    Mathematical modeling of bioremediation of trichloroethylene in aquifers

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    AbstractTrichloroethylene (TCE) is a very common contaminant of groundwater. It is used as an industrial solvent and is frequently poured into the soil. There exist bacteria that can degrade TCE. In contrast with most cases of bioremediation, the bacteria that degrade TCE do not use it as a carbon source. Instead the bacteria produce an enzyme to metabolize methane. This enzyme can degrade other organics including TCE. In this paper we model in situ bioremediation of TCE in an aquifer by using two species of bacteria: one that forms biobarriers to restrict the movement of TCE and the second one to reduce TCE. The model includes flow of water, transport of TCE and the nutrients, bacterial growth and degradation of TCE. Nonstandard numerical methods are used to discretize the equations. Some results are presented

    Origin and evolution of surface spin current in topological insulators

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    The Dirac surface states of topological insulators offer a unique possibility for creating spin polarized charge currents due to the spin-momentum locking. Here we demonstrate that the control over the bulk and surface contribution is crucial to maximize the charge-to-spin conversion efficiency. We observe an enhancement of the spin signal due to surface-dominated spin polarization while freezing out the bulk conductivity in semiconducting Bi1.5Sb0.5Te1.7Se1.3 below 100K. Detailed measurements up to room temperature exhibit a strong reduction of the magnetoresistance signal between 2 and 100K, which we attribute to the thermal excitation of bulk carriers and to the electron-phonon coupling in the surface states. The presence and dominance of this effect up to room temperature is promising for spintronic science and technology

    Decarboxylating free fatty acids into fuels using subcritical water

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    Biofuel producers are looking into new avenues for utilization of their byproducts to improve their profitability in an environmentally friendly way. The biodiesel market has become saturated with very low margins and blenders cannot utilize this product in the winter. In order to address this problem, attention has now shifted towards a range of other possible products that can be made from non-food grade byproduct oils, including green diesel (a diesel having the same analytical signature as petroleum diesel), jet fuels, and other high value products. The major goal of this work was to investigate the hydrothermal conversion of bio-oil to fuel grade hydrocarbons as green diesel. Oleic acid was selected as a model compound of bio-oil to understand the reaction chemistry. Hydrothermal reactions were carried out in a CSTR (batch mode) from 300 to 450oC and reaction time was varied from 10 minutes to 6 hours. GC-FID and GC-TCD were used to analyze the liquid and gas samples, respectively. GC-TCD results showed that decarboxylation and decarbonylation of oleic acid was occurred whereas decarboxylation is the dominating chemical reaction. FTIR results also confirmed the decarboxylation of oleic acid and density measurement of the liquid proves that it falls between the diesel and kerosene. Please click Additional Files below to see the full abstract
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