58,807 research outputs found

    Transversality Properties: Primal Sufficient Conditions

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    The paper studies 'good arrangements' (transversality properties) of collections of sets in a normed vector space near a given point in their intersection. We target primal (metric and slope) characterizations of transversality properties in the nonlinear setting. The Holder case is given a special attention. Our main objective is not formally extending our earlier results from the Holder to a more general nonlinear setting, but rather to develop a general framework for quantitative analysis of transversality properties. The nonlinearity is just a simple setting, which allows us to unify the existing results on the topic. Unlike the well-studied subtransversality property, not many characterizations of the other two important properties: semitransversality and transversality have been known even in the linear case. Quantitative relations between nonlinear transversality properties and the corresponding regularity properties of set-valued mappings as well as nonlinear extensions of the new transversality properties of a set-valued mapping to a set in the range space due to Ioffe are also discussed.Comment: 33 page

    On a nonlinear heat equation associated with Dirichlet -- Robin conditions

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    This paper is devoted to the study of a nonlinear heat equation associated with Dirichlet-Robin conditions. At first, we use the Faedo -- Galerkin and the compactness method to prove existence and uniqueness results. Next, we consider the properties of solutions. We obtain that if the initial condition is bounded then so is the solution and we also get asymptotic behavior of solutions as. Finally, we give numerical resultsComment: 20 page

    An induction theorem and nonlinear regularity models

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    A general nonlinear regularity model for a set-valued mapping F:X×R+YF:X\times R_+\rightrightarrows Y, where XX and YY are metric spaces, is considered using special iteration procedures, going back to Banach, Schauder, Lusternik and Graves. Namely, we revise the induction theorem from Khanh, J. Math. Anal. Appl., 118 (1986) and employ it to obtain basic estimates for studying regularity/openness properties. We also show that it can serve as a substitution of the Ekeland variational principle when establishing other regularity criteria. Then, we apply the induction theorem and the mentioned estimates to establish criteria for both global and local versions of regularity/openness properties for our model and demonstrate how the definitions and criteria translate into the conventional setting of a set-valued mapping F:XYF:X\rightrightarrows Y.Comment: 28 page

    Willingness to Pay for the Preservation of Lo Go - Xa Mat National Park in Vietnam

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    Lo Go - Xa Mat National Park has great value in terms of biodiversity but preserving the park is a great challenge for the Vietnamese government. This study estimated the willingness to pay of households to preserve Lo Go - Xa Mat National Park, using the contingent valuation method. We employed the single-bounded dichotomous choice question format to estimate how much households in Ho Chi Minh City were willing to contribute towards a preservation plan for the park. This plan comprised twelve preservation activities and compensating the local communities for their foregone income. The study found that households in Ho Chi Minh City were willing to pay at least VND 6,209 per month for three years for the preservation of Lo Go - Xa Mat National Park. With protest votes included, factors strongly affecting households' willingness to pay were bid amount and the amount of their monthly electricity bill. The education level of the respondents and the number of working people in the household had significant but lesser impact on their willingness to pay. Without protest votes, the bid amount, monthly electricity bill amount and education level of respondents significantly affected willingness to pay. We found that the annualized benefit value of the project was larger than its annualized cost. This indicated that the preservation plan was economically viable. This study does not provide the total value of Lo Go - Xa Mat National Park, but it shows the great value of the park in terms of local households' willingness to pay for its preservation and this is important information for policy-makers in deciding how to protect the park efficiently.willingness to pay, Vietnam

    The 'Sphere': A Dedicated Bifurcation Aneurysm Flow-Diverter Device.

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    We present flow-based results from the early stage design cycle, based on computational modeling, of a prototype flow-diverter device, known as the 'Sphere', intended to treat bifurcation aneurysms of the cerebral vasculature. The device is available in a range of diameters and geometries and is constructed from a single loop of NITINOL(®) wire. The 'Sphere' reduces aneurysm inflow by means of a high-density, patterned, elliptical surface that partially occludes the aneurysm neck. The device is secured in the healthy parent vessel by two armatures in the shape of open loops, resulting in negligible disruption of parent or daughter vessel flow. The device is virtually deployed in six anatomically accurate bifurcation aneurysms: three located at the Basilar tip and three located at the terminus bifurcation of the Internal Carotid artery (at the meeting of the middle cerebral and anterior cerebral arteries). Both steady state and transient flow simulations reveal that the device presents with a range of aneurysm inflow reductions, with mean flow reductions falling in the range of 30.6-71.8% across the different geometries. A significant difference is noted between steady state and transient simulations in one geometry, where a zone of flow recirculation is not captured in the steady state simulation. Across all six aneurysms, the device reduces the WSS magnitude within the aneurysm sac, resulting in a hemodynamic environment closer to that of a healthy vessel. We conclude from extensive CFD analysis that the 'Sphere' device offers very significant levels of flow reduction in a number of anatomically accurate aneurysm sizes and locations, with many advantages compared to current clinical cylindrical flow-diverter designs. Analysis of the device's mechanical properties and deployability will follow in future publications
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