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Frontiers of Structural and Civil Engineering 2022年第7期16卷 928-945页

作者： van Quan TRAN Hai-van Thi MAI Thuy-Anh NGUYEN Hai-Bang LY Faculty of Civil Engineering University of Transport TechnologyHanoi 100000Vietnam

The compressive strength of self-compacting concrete(SCC)needs to be determined during the construction design *** paper shows that the compressive strength of SCC(CS of SCC)can be successfully predicted from mix design and curing age by a machine learning(ML)technique named the Extreme Gradient Boosting(XGB)algorithm,including non-hybrid and hybrid *** ML techniques,such as Linear regression(LR),K-Nearest Neighbors(KNN),Support Vector Machine(SVM),Decision Trees(DTR),Random Forest(RF),Gradient Boosting(GB),and Artificial Neural Network using two training algorithms LBFGS and SGD(denoted as ANN_LBFGS and ANN_SGD),are also compared with the XGB ***,the hybrid models of eight ML techniques and Particle Swarm Optimization(PSO)are constructed to highlight the reliability and accuracy of SCC compressive strength prediction by the XGB_PSO hybrid *** highest number of SCC samples available in the literature is collected for building the ML *** with previously published works’performance,the proposed XGB method,both hybrid and non-hybrid models,is the most reliable and robust of the examined techniques,and is more accurate than existing ML methods(R2=0.9644,RMSE=4.7801,and MAE=3.4832).Therefore,the XGB model can be used as a practical tool for engineers in predicting the CS of SCC.

关键词： compressive strength self-compacting concrete machine learning techniques particle swarm optimization extreme gradient boosting

Chemical constituents and biological activities of essential oils of Amomum genus(Zingiberaceae)

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Asian Pacific Journal of Tropical Biomedicine 2021年第12期11卷 519-526页

作者： Hong Thien van Institute of Biotechnology and Food Technology Industrial University of Ho Chi Minh CityHo Chi Minh CityVietnam

Amomum *** the aromatic and medicinal plants native to tropical and subtropical Asia belonging to the family *** of Amomum genus have been used for a long time in traditional medicine for the treatment of throat trouble,congestion of lungs,inflammation of eyelids,and digestive disorders,*** essential oils have been studied for their chemical profiles in which limonene,allo-aromadendrene,1,8-cineole,camphor,farnesyl acetate,α-pinene,β-pinene,caryophyllene,camphene,D-camphor,santolina triene,methyl chavicol,bornyl acetate,β-elemene,δ-3-carene,*** the major ***,the oils extracted from Amomum plants have been reported to possess antimicrobial,antioxidant,insecticidal,larvicidal,cytotoxic,anti-scabies,and anti-inflammatory *** review focuses on the chemical constituents and biological activities of the essential oils isolated from the different plant parts of Amomum *** objective of the present review is to highlight therapeutic potentials and provide evidence for future medicinal applications of these species of genus Amomum.

关键词： Amomum Zingiberaceae Essential oil Bioactivity

Crop type mapping using LiDAR,Sentinel-2 and aerial imagery with machine learning algorithms

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Geo-Spatial Information Science 2021年第2期24卷 215-227,I0003页

作者： Adriaan Jacobus Prins Adriaan van Niekerk Department of Geography&Environmental Studies Stellenbosch UniversityStellenboschSouth Africa

LiDAR data are becoming increasingly available,which has opened up many new *** such application is crop type *** crop type maps are critical for monitoring water use,estimating harvests and in precision *** traditional approach to obtaining maps of cultivated fields is by manually digitizing the fields from satellite or aerial imagery and then assigning crop type labels to each field-often informed by data collected during ground and aerial ***,manual digitizing and labeling is time-consuming,expensive and subject to human *** remote sensing methods is a cost-effective alternative,with machine learning gaining popularity for classifying crop *** study evaluated the use of LiDAR data,Sentinel-2 imagery,aerial imagery and machine learning for differentiating five crop types in an intensively cultivated *** combinations of the three datasets were evaluated along with ten machine *** classification results were interpreted by comparing overall accuracies,kappa,standard deviation and *** was found that LiDAR data successfully differentiated between different crop types,with XGBoost providing the highest overall accuracy of 87.8%.Furthermore,the crop type maps produced using the LiDAR data were in general agreement with those obtained by using Sentinel-2 data,with LiDAR obtaining a mean overall accuracy of 84.3%and Sentinel-2 a mean overall accuracy of 83.6%.However,the combination of all three datasets proved to be the most effective at differentiating between the crop types,with RF providing the highest overall accuracy of 94.4%.These findings provide a foundation for selecting the appropriate combination of remotely sensed data sources and machine learning algorithms for operational crop type mapping.

关键词： LiDAR multispectral imagery sentinel-2 machine learning crop type classification per-pixel classification

Finite element analysis of functionally graded sandwich plates with porosity via a new hyperbolic shear deformation theory

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Defence Technology（防务技术） 2022年第3期18卷 490-508页

作者： Pham van Vinh Le Quang Huy Department of Solid Mechanics Le Quy Don Technical University236 Hoang Quoc VietHanoiViet Nam Institute of Techniques for Special Engineering Le Quy Don Technical University236 Hoang Quoc VietHanoiViet Nam

This study focusses on establishing the finite element model based on a new hyperbolic sheareformation theory to investigate the static bending,free vibration,and buckling of the functionally graded sandwich plates with *** novel sandwich plate consists of one homogenous ceramic core and two different functionally graded face sheets which can be widely applied in many fields of engineering and defence *** discrete governing equations of motion are carried out via Hamilton’s principle and finite element *** computation program is coded in MATLAB software and used to study the mechanical behavior of the functionally graded sandwich plate with *** present finite element algorithm can be employed to study the plates with arbitrary shape and boundary *** obtained results are compared with available results in the literature to confirm the reliability of the present ***,a comprehensive investigation of the effects of several parameters on the bending,free vibration,and buckling response of functionally graded sandwich plates is *** numerical results shows that the distribution of porosity plays significant role on the mechanical behavior of the functionally graded sandwich plates。

关键词： Functionally graded sandwich plates Porous plates Hyperbolic shear deformation theory Bending analysis Free vibration analysis Buckling analysis

On the positive nonoscillatory solutions of the difference equation Xn＋1=α＋（xn-k/xn-m）^p

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Applied Mathematics(A Journal of Chinese Universities) 2009年第1期24卷 45-48页

作者： VU van KHUONG Dept. of Math. Anal. Univ. of Transport and Communications Hanoi City Vietnam

The aim of this paper is to show that the following difference equation：Xn＋1=α＋（xn-k/xn-m）^p, n=0,1,2,…,where α 〉 -1, p 〉 O, k,m ∈ N are fixed, 0 ≤ m 〈 k, x-k, x-k＋1,…,x-m,…,X-1, x0 are positive, has positive nonoscillatory solutions which converge to the positive equilibrium x=α＋1. It is interesting that the method described in the paper, in some cases can also be applied when the parameter α is variable.

关键词： equilibrium asymptotic positive solution difference equation nonoscillatory solution

Indian plate paleogeography, subduction and horizontal underthrusting below Tibet: paradoxes, controversies and opportunities

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National Science Review 2022年第8期9卷 175-193页

作者： Douwe J.J.van Hinsbergen Department of Earth Sciences Utrecht University

The India–Asia collision zone is the archetype to calibrate geological responses to continent–continent collision, but hosts a paradox: there is no orogen-wide geological record of oceanic subduction after initial collision around 60–55 Ma, yet thousands of kilometers of post-collisional subduction occurred before the arrival of unsubductable continental lithosphere that currently horizontally underlies Tibet. Kinematically restoring incipient horizontal underthrusting accurately predicts geologically estimated diachronous slab break-off, unlocking the Miocene of Himalaya–Tibet as a natural laboratory for unsubductable lithosphere convergence. Additionally, three endmember paleogeographic scenarios exist with different predictions for the nature of post-collisional subducted lithosphere but each is defended and challenged based on similar data types. This paper attempts at breaking through this impasse by identifying how the three paleogeographic scenarios each challenge paradigms in geodynamics, orogenesis, magmatism or paleogeographic reconstruction and identify opportunities for methodological a.vances in paleomagnetism, sediment provenance analysis, and seismology to conclusively constrain Greater Indian paleogeography.

关键词： collision orogenesis subduction reconstruction Himalaya Tibet

Extensions of Certain Modules Over the First Weyl Algebra

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Science China Mathematics 1994年第5期37卷 535-546页

作者：肖杰 Freddy van Oystaeyen Department of Mathematics Beijing Normal UniversityBeijing 100875PRC Department of Mathematics University of Antwerp UIA Antwerpen B-2610 Belgium

Using a method stemming from the representation theory of finite-dimensional algebra’s,results about a category of Artinian modules over the first Weyl algebra consisting of objects having composition series with composition factors isomorphic to prescribed ones have been *** category corresponds to a tube of Z/2Z type and it is serial and *** Auslander-Reiten formula in this category describing the functor Ext,,(-,-) in terms of the AR-quiver has been *** dimensions of Ext4(M,N) for M and N in different tubes are calculated.

关键词： Weyl algebra Artinian module tube

Travelling Waves for a Density Dependent Diffusion Nagumo Equation over the Real Line

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Communications in Theoretical Physics 2012年第7期58卷 5-11页

作者： Robert A. van Gorder Department of Mathematics University of Central FloridaP.O.Box 161364OrlandoFL 32816-1364USA

We consider the density dependent diffusion Nagumo equation, where the diffusion coefficient is a simple power function. This equation is used in modelling electrical pulse propagation in nerve axons and in population genetics (amongst other areas). In the present paper, the δ-expansion method is applied to a travelling wave reduction of the problem, so that we may obtain globally valid perturbation solutions (in the sense that the perturbation solutions are valid over the entire infinite domain, not just locally; hence the results are a generalization of the local solutions considered recently in the literature). The resulting boundary value problem is solved on the real line subject to conditions at z →±∞. Whenever a perturbative method is applied, it is important to discuss the accuracy and convergence properties of the resulting perturbation expansions. We compare our results with those of two different numerical methods (designed for initial and boundary value problems, respectively) and deduce that the perturbation expansions agree with the numerical results after a reasonable number of iterations. Finally, we are able to discuss the influence of the wave speed c and the asymptotic concentration value α on the obtained solutions. Upon recasting the density dependent diffusion Nagumo equation as a two-dimensional dynamical system, we are also able to discuss the influence of the nonlinear density dependence (which is governed by a power-law parameter m) on oscillations of the travelling wave solutions.

关键词： density dependent diffusion equation nonlinear partial differential equation perturbation method δ-expansion method

Symmetries of the interacting boson model

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Frontiers of physics 2018年第6期13卷 79-88页

作者： P. van Isacker Grand Accelerateur National d'Ions Lourds CEA//DRF CNRS//IN2P3 Bd Henri Becquerel BP 55027 F-14076 Caen France

This contribution reviews the symmetry properties of the interacting boson model of Arima and Iachello. While the concept of a dynamical symmetry is by now a familiar one, this is not necessarily so for the extended notions of partial dynamical symmetry and quasi dynamical symmetry, which can be beautifully illustrated in the context of the interacting boson model. The main conclusion of the analysis is that dynamical symmetries are scarce while their partial and quasi extensions are ubiquitous.

关键词： interacting boson model

Optimal use of mobile cooling units in a deep-level gold mine

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International Journal of Mining Science and Technology 2020年第4期30卷 547-553页

作者： H.J.van Staden J.F.van Rensburg H.J.Groenewald Centre for Research and Continued Engineering Development North-West UniversityPretoria 0081South Africa

The South African gold mining sector remains a significant contributor to the country’s *** several challenges that hinder the realisation of South Africa’s full mineral potential,the sector’s sustainability and profitability can be enhanced through implementing operational improvement *** cooling units(MCUs)were identified as a potential focus area for operational *** are used as tertiary or in-stope cooling in hot underground *** this paper,a method was presented to characterise the performance of existing MCUs based on three key performance indicators(KPIs),namely,the wet-bulb temperature ratio(WTR),efficiency and *** strategies were then elected and implemented based on these *** implementation of this method in a South African gold mine attained a reduction in pumped water volumes,reduced operating costs through electricity cost savings and improvements in underground ventilation air temperatures.

关键词： Mobile cooling units Optimisation Mine cooling performance Electricity cost savings Spot cooling