145 research outputs found

    Optimality conditions in terms of Bouligand generalized differentials for a nonsmooth semilinear elliptic optimal control problem with distributed and boundary control pointwise constraints

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    We prove a novel optimality condition in terms of Bouligand generalized differentials for a local minimizer of optimal control problems governed by a nonsmooth semilinear elliptic partial differential equation with both distributed and boundary unilateral pointwise control constraints, in which the nonlinear coefficient in the state equation is not differentiable at one point. Therefore, the Bouligand subdifferential of this nonsmooth coefficient in every point consists of one or two elements that will be used to construct the two associated Bouligand generalized derivatives of the control-to-state operator in any admissible control. We also establish the optimality conditions in the form of multiplier existence. There, in addition to the existence of the adjoint state and of the nonnegative multipliers associated with the pointwise constraints as usual, other nonnegative multipliers exist and correspond to the nondifferentiability of the control-to-state mapping. The latter type of optimality conditions shall be applied to the optimal control problems without distributed and boundary pointwise constraints to derive the so-called \emph{strong} stationarity conditions, where the sign of the associated adjoint state does not vary on the level set of the corresponding optimal state at the value of nondifferentiability.Comment: 33 page

    Nonlinear static and transient isogeometric analysis of functionally graded microplates based on the modified strain gradient theory

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    The objective of this study is to develop an effective numerical model within the framework of an isogeometric analysis (IGA) to investigate the geometrically nonlinear responses of functionally graded (FG) microplates subjected to static and dynamic loadings. The size effect is captured based on the modified strain gradient theory with three length scale parameters. The third-order shear deformation plate theory is adopted to represent the kinematics of plates, while the geometric nonlinearity is accounted based on the von Kármán assumption. Moreover, the variations of material phrases through the plate thickness follow the rule of mixture. By using Hamilton’s principle, the governing equation of motion is derived and then discretized based on the IGA technique, which tailors the non-uniform rational B-splines (NURBS) basis functions as interpolation functions to fulfil the C2-continuity requirement. The nonlinear equations are solved by the Newmark’s time integration scheme with Newton-Raphson iterative procedure. Various examples are also presented to study the influences of size effect, material variations, boundary conditions and shear deformation on the nonlinear behaviour of FG microplates

    Delay factors in the construction of irrigation and hydropower projects in Vietnam

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    Irrigation and hydropower are among the most important sectors in the construction industry that propel the economic needs of a developing country like Vietnam. The construction of these projects often suffers from severe delays, leading to financial losses and other negative impacts on the economy. This paper aims to determine delay factors in the construction of these projects. Among many, 39 most important candidates of delay causes were identified from the literature review. Further surveys on project participants were conducted for the severity of these causes. An exploratory factor analysis was utilized to identify latent factors that cause delays in construction projects. The analysis result categorized a few groups of factors such as abnormal factors on the construction site (e.g., labor accidents, hydrology, water flow, extreme weather) and technical factors related to the construction contractor (e.g., unsuitable schedule, outdated construction technology, unprofessional workers) that have the greatest impact on the delay in construction of irrigation and hydropower projects in Vietnam. These findings contribute to the body of knowledge of project management and risk management, hence an improvement in the efficiency of the project sectors’ performance

    Linear Approximation and Asymptotic Expansion of Solutions for a Nonlinear Carrier Wave Equation in an Annular Membrane with Robin-Dirichlet Conditions

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    This paper is devoted to the study of a nonlinear Carrier wave equation in an annular membrane associated with Robin-Dirichlet conditions. Existence and uniqueness of a weak solution are proved by using the linearization method for nonlinear terms combined with the Faedo-Galerkin method and the weak compact method. Furthermore, an asymptotic expansion of a weak solution of high order in a small parameter is established

    Behavioral Improvements and its Molecular Mechanism of Ilex kudingcha C.J. Tseng on Animal Model of Alzheimer’s Disease

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    Alzheimer's disease (AD) is a common chronic neurodegenerative disease with well-defined pathophysiological mechanisms. Ilex kudingcha (IK) C.J. Tseng is commonly known as bitter tea or “Khom” tea in Vietnam. The present study was conducted to investigate the anti-dementia effect of IK using olfactory bulbectomized (OBX) mice. OBX mice were daily treated with IK extract (540 mg/kg) or reference drug, tacrine (2.5 mg/kg) 1 week before and continuously for 3 days after the OBX surgery. The object recognition test, modified Y maze test and fear conditioning test were employed to analyze non-spatial short-term, spatial short-term and long-term memories of the mice respectively. Administration of IK extract and tacrine attenuated these OBX-induced cognitive deficits in mice. The effects of IK and tacrine on spatial short-term memory impairment were reversed by scopolamine, a muscarinic receptor antagonist. The amyloid-beta (Aβ) production in adult transgenic Drosophila brain flies was also investigated by using Western blotting with APP-HA antibody. These results indicated that IK extract improves short-term and long-term memory disturbances in OBX mice and that muscarinic receptor may play a role on these actions. In addition, our result also showed that IK extract reduces the expression of amyloid precursor protein (APP) in brain of AD model using Drosophila melanogaster

    Depth-dose distribution in potatoes with low-energy X-rays

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    Irradiation is known as a handful measure to inhibit potato sprouting, kill harmful bacteria, and increase preservation. The absorbed dose is one of the essential characteristics of the irradiation process. In this study, the depth-dose distributions in potatoes and polymethyl methacrylate were investigated under low-energy X-ray irradiation by using the Fricke dosimeter and Gafchromic film dosimeter. The dose rates required for the rays to penetrate in polymethyl methacrylate were compared with those in potatoes. Polymethyl methacrylate could be used as a phantom in measuring the depth dose delivered in potatoes. The difference in depth-dose distribution in potatoes between one-sided and double-sided irradiation was also investigated. The calculated dose uniformity ratio values are 5.8 and 1.9 for potatoes irradiating one-sided and double-sided

    SECURITY CAPABILITY ANALYSIS OF COGNITIVE RADIO NETWORK WITH SECONDARY USER CAPABLE OF JAMMING AND SELF-POWERING

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    This paper investigates a cognitive radio network where a secondary sender assists a primarytransmitter in relaying primary information to a primary receiver and also transmits its own information toa secondary recipient. This sender is capable of jamming to protect secondary and/or primary informationagainst an eavesdropper and self-powering by harvesting radio frequency energy of primary signals.Security capability of both secondary and primary networks are analyzed in terms of secrecy outageprobability. Numerous results corroborate the proposed analysis which serves as a design guidelineto quickly assess and optimize security performance. More importantly, security capability trade-offbetween secondary and primary networks can be totally controlled with appropriate selection of systemparameters
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