148 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
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
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
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
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
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
AMRViz enables seamless genomics analysis and visualization of antimicrobial resistance
We have developed AMRViz, a toolkit for analyzing, visualizing, and managing bacterial genomics samples. The toolkit is bundled with the current best practice analysis pipeline allowing researchers to perform comprehensive analysis of a collection of samples directly from raw sequencing data with a single command line. The analysis results in a report showing the genome structure, genome annotations, antibiotic resistance and virulence profile for each sample. The pan-genome of all samples of the collection is analyzed to identify core- and accessory-genes. Phylogenies of the whole genome as well as all gene clusters are also generated. The toolkit provides a web-based visualization dashboard allowing researchers to interactively examine various aspects of the analysis results. Availability: AMRViz is implemented in Python and NodeJS, and is publicly available under open source MIT license at https://github.com/amromics/amrviz
Depth-dose distribution in potatoes with low-energy X-rays
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
- …