165 research outputs found
A functional limit theorem for lattice oscillating random walk
The paper is devoted to an invariance principle for Kemperman's model of
oscillating random walk on . This result appears as an extension of
the invariance principal theorem for classical random walks on or
reflected random walks on . Relying on some natural Markov
sub-process which takes into account the oscillation of the random walks
between and , we first construct an aperiodic
sequence of renewal operators acting on a suitable Banach space and then apply
a powerful theorem proved by S. Gou\"ezel
Advanced Control of the dynamic voltage restorer for mitigating voltage sags in power systems
The paper presents a vector control with
two cascaded loops to improve the properties of Dynamic
Voltage Restorer (DVR) to minimize Voltage
Sags on the grid. Thereby, a vector controlled structure
was built on the rotating dq-coordinate system
with the combination of voltage control and the current
control. The proposed DVR control method is modelled
using MATLAB-Simulink. It is tested using balanced/
unbalanced voltage sags as well as fluctuant and
distorted voltages. As a result, by using this controlling
method, the dynamic characteristics of the system have
been improved significantly. The system performed with
higher accuracy, faster response and lower distortion in
the voltage sags compensation. The paper presents real
time experimental results to verify the performance of
the proposed method in real environments
Determination of the content of major chemical components and bioactive compounds and antioxidant ability of Hong Quan (Flacourtia jangomas (Lour.) Raeusch) fruit cultivated in An Giang, Vietnam
Hong Quan (Flacourtia jangomas (Lour.) Raeusch) is a new fruit that has appeared recently and it is cultivated with other orchards or under forest canopy of Tri Ton and Tinh Bien district at An Giang province. Since this fruit has not been popularized in Vietnam, there is a shortage in research about chemical compositions of Hong Quan. Therefore, quantitative analysis of main chemical components, bioactive compounds and antioxidant activity of this kind of fruit need to be carried out to enhance its applications in food. Results showed that Hong Quan fruits contain 76.50% ± 2.56 of moisture, carbohydrate is 24.86% ± 1.54, protein is 9.19% ± 0.49, lipid is 0.68% ± 0.21, total sugar is 10,91% ± 0.88, ash is 1.05% ± 0.08, fiber is 8.39% ± 0.95 and vitamin C is 81.62 ± 3.99 mg/100g. The content of bioactive compounds such as carotenoids, phenolics, tannins, alkaloids, saponins and flavonoids were 9.87 ± 0.40 mg/100g, 456.32 ± 23.81 mgGAE/100g, 944.08 ± 26.31 mgTAE/100g, 586.68 ± 44.56 mgCE/100g, 20.87 ± 2.00 mgSE/100g and 65.95 ± 2.92 mgQE/100g fresh weight respectively. Moreover, antioxidant capacity of extract ethanol from fruit was high level as the free radical scavenging ability (DPPH) at 88.65% ± 1.23, the ability to reduce iron (FRAP) at 15.24 ± 0.26 mM FeSO4/100g and the antioxidant ability index (AAI) at 8.13 ± 0.82. Hong Quan fruit promisingly could be a good source of commercial processing products or cosmetic due to high level of nutrients and functional compounds
Globally Convergent Coderivative-Based Generalized Newton Methods in Nonsmooth Optimization
This paper proposes and justifies two globally convergent Newton-type methods
to solve unconstrained and constrained problems of nonsmooth optimization by
using tools of variational analysis and generalized differentiation. Both
methods are coderivative-based and employ generalized Hessians (coderivatives
of subgradient mappings) associated with objective functions, which are either
of class , or are represented in the form of convex
composite optimization, where one of the terms may be extended-real-valued. The
proposed globally convergent algorithms are of two types. The first one extends
the damped Newton method and requires positive-definiteness of the generalized
Hessians for its well-posedness and efficient performance, while the other
algorithm is of {the regularized Newton type} being well-defined when the
generalized Hessians are merely positive-semidefinite. The obtained convergence
rates for both methods are at least linear, but become superlinear under the
semismooth property of subgradient mappings. Problems of convex composite
optimization are investigated with and without the strong convexity assumption
{on smooth parts} of objective functions by implementing the machinery of
forward-backward envelopes. Numerical experiments are conducted for Lasso
problems and for box constrained quadratic programs with providing performance
comparisons of the new algorithms and some other first-order and second-order
methods that are highly recognized in nonsmooth optimization.Comment: arXiv admin note: text overlap with arXiv:2101.1055
ADI method based on C2-continuous two-node integrated-RBF elements for viscous flows
We propose a C2-continuous alternating direction implicit (ADI) method for the solution of the streamfunction-vorticity equations governing steady 2D incompressible viscous fluid flows. Discretisation is simply achieved with Cartesian grids. Local two-node integrated radial basis function elements (IRBFEs) [D.-A. An-Vo, N. Mai-Duy, T. Tran-Cong, A C2-continuous control-volume technique based on Cartesian grids and two-node integrated-RBF elements for second-order elliptic problems, CMES: Computer Modeling in Engineering & Sciences 72 (2011) 299-334] are used for the discretisation of the diffusion terms, and then the convection terms are incorporated into system matrices by treating nodal derivatives as unknowns. ADI procedure is applied for the time integration. Following ADI factorisation, the two-dimensional problem becomes a sequence of one-dimensional problems. The solution strategy consists of multiple use of a one-dimensional sparse matrix algorithm that helps saving the computational cost. High levels of accuracy and efficiency of the present methods are demonstrated with solutions of several benchmark problems defined on rectangular and non-rectangular domains
A comprehensive evaluation of polygenic score and genotype imputation performances of human SNP arrays in diverse populations
publishedVersio
The Effect of ENSO on Hydrological Structure and Environment in the South Central Coast – Vietnam
ENSO (El Niño-Southern Oscillation) phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general. In case of Vietnamese South-Central Waters, impacts of ENSO only focused on issues of changing seasonal wind, seawater temperature anomalies, changing of water masses as the air-sea interaction. Based on several data sets collecting in the period of 2003-2017, new finding of seawater temperature, salinity and environmental factors was identified in the water masses of Vietnamese South-Central Waters. The highest salinity was 35.4 ‰. During the El Nino event, increasing water temperature and salinity caused to move the deeper water masses to be closer to the sea surface than that initial depth in the neutral period. During the La Nina event, the temperature of most water masses reduced by 0.1-3°C, and then these water masses could be affected to the deeper layer. During the phase from strong ENSO event towards the neutral time, nutrient salts of the 4 water masses were lower concentration in the neutral year, causing the lack of phosphorus in sea surface water masses
Disinfection performance of an ultraviolet lamp: a CFD investigation
Ultraviolet (UV)-based devices have shown their effectiveness on various germicidal purposes. To serve their design optimisation, the disinfection effectiveness of a vertically cylindrical UV lamp, whose wattage ranges from P = 30 − 100 W, is numerically investigated in this work. The UV radiation is solved by the Finite Volume Method together with the Discrete Ordinates model. Various results for the UV intensity and its bactericidal effects against several popular virus types, i.e., Corona-SARS, Herpes (type 2), and HIV, are reported and analysed in detail. Results show that the UV irradiance is greatly dependent on the lamp power. Additionally, it is indicated that the higher the lamp wattage employed, the larger the bactericidal rate is observed, resulting in the greater effectiveness of the UV disinfection process. Nevertheless, the wattage of P ≤ 100W is determined to be insufficient for an effective disinfection performance in a whole room; higher values of power must hence be considered in case intensive sterilization is required. Furthermore, the germicidal effect gets reduced with the viruses less sensitive to UV rays, e.g, the bactericidal rate against the HIV virus is only ∼8.98% at the surrounding walls
Residual Cardiovascular Risk Factors in Dyslipidemia
Cardiovascular disease poses a major challenge for the 21st century. Although good control of blood pressure and type 2 diabetes and reducing low-density lipoprotein-cholesterol levels can improve cardiovascular outcomes, a substantial residual risk remains existed after treatment in most patient populations. Recently, many efforts have been directed at finding the important role of low high-density-lipoprotein cholesterol, high triglycerides, especially triglyceride-rich lipoproteins and lipoprotein (a) in the metabolism of atherosclerotic plaque formation Therefore, based on the recent evidence, identification and treatment of these risk factors may play a role in optimizing therapeutic strategy, particularly in high risk subjects along with conventional treatment. In clinical practice, adequate attention should be paid when screening and managing residual cardiovascular risk factors in dyslipidemia in term of individualized approach. The ongoing trials will give more answers to elucidate this important area
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