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Analysis of the factors affecting LiDAR DTM accuracy in a steep shrub area

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International Journal of Digital Earth 2011年第6期4卷 521-538页

作者： J.Estornell L.A.Ruiz B.Vela´zquez-Martı´ T.Hermosilla departamento de ingenierı´a Cartogra´fica Geodesia y Fotogrametrı´aUniversidad Polite´cnica de ValenciaCamino de Vera s/nValencia 46022Spain departamento de ingenierı´a Rural y Agroalimentaria Universidad Polite´cnica de ValenciaValenciaSpain

The creation of a quality Digital Terrain Model(DTM)is essential for representing and analyzing the Earth in a digital form.The continuous improvements in the acquisition and the potential of airborne Light detection and Ranging(LiDAR)data are increasing the range of applications of this technique to the study of the Earth surface.The aim of this study was to determine the optimal parameters for calculating a DTM by using an iterative algorithm to select minimum elevations from LiDAR data in a steep mountain area with shrub vegetation.The parameters were:input data type,analysis window size,and height thresholds.The effects of slope,point density,and vegetation on DTM accuracy were also analyzed.The results showed that the lowest root mean square error(RMSE)was obtained with an analysis window size of 10 m,5 m,and 2.5 m,rasterized data as input data,and height thresholds equal to or greater than 1.5 m.These parameters showed a RMSE of 0.19 m.When terrain slope varied from 010%to 5060%,the RMSE increased by 0.11 m.The RMSE decreased by 0.06 m when point density was increased from 4 to 8 points/m2,and increased by 0.05 m in dense vegetation areas.

关键词： LiDAR digital earth Digital Terrain Model(DTM) filtering 3-D representation

Combined heat and mass transfer by mixed convection MHD flow along a porous plate with chemical reaction in presence of heat source

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Applied Mathematics and Mechanics(English Edition) 2010年第10期31卷 1217-1230页

作者： J.ZUECO S.AHMED ETS ingeniería Industrial Departamento de Ingeniería Térmicay FluidosUniversidad Politécnica de Cartagena Fluid Dynamics Research Department of MathematicsGoalpara College

An exact and a numerical solutions to the problem of a steady mixed convective MHD flow of an incompressible viscous electrically conducting fluid past an infinite vertical porous plate with combined heat and mass transfer are presented.A uniform magnetic field is assumed to be applied transversely to the direction of the flow with the consideration of the induced magnetic field with viscous and magnetic dissipations of energy.The porous plate is subjected to a constant suction velocity as well as a uniform mixed stream velocity.The governing equations are solved by the perturbation technique and a numerical method.The analytical expressions for the velocity field,the temperature field,the induced magnetic field,the skin-friction,and the rate of heat transfer at the plate are obtained.The numerical results are demonstrated graphically for various values of the parameters involved in the problem.The effects of the Hartmann number,the chemical reaction parameter,the magnetic Prandtl number,and the other parameters involved in the velocity field,the temperature field,the concentration field,and the induced magnetic field from the plate to the fluid are discussed.An increase in the heat source/sink or the Eckert number is found to strongly enhance the fluid velocity values.The induced magnetic field along the x-direction increases with the increase in the Hartmann number,the magnetic Prandtl number,the heat source/sink,and the viscous dissipation.It is found that the flow velocity,the fluid temperature,and the induced magnetic field decrease with the increase in the destructive chemical reaction.Applications of the study arise in the thermal plasma reactor modelling,the electromagnetic induction,the magnetohydrodynamic transport phenomena in chromatographic systems,and the magnetic field control of materials processing.

关键词： MHD perturbation technique network simulation method Eckert number mixed convection induced magnetic field viscous dissipation heat source/sink

Environmental geochemistry:Introduction

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Geoscience Frontiers 2022年第1期13卷 374-375页

作者： Luis F.O.Silva Marcos L.S.Oliveira department of Civil and Environmental.Universidad de la Costa CUCCalle 58#55-66BarranquillaAtlánticoColombia departamento de ingeniería Civil y Arquitectura Universidad de LimaAvenida Javier Prado Este 4600Santiago de Surco 1503Peru

Assessing the physical,geographic,chemical,and geological aspects are important to understand environmental impacts as well as health concerns in view of building a more sustainable planet with circular economies that would last for the foreseeable future.In the recent years,the significance of incorporating ecosystem,anthropogenic activities,and climate has fortified from being an academic concern(e.g.,WEF,2011)into a broadly societal concern as the forecasted realities of environmental deterioration and global climate change come to pass.

关键词： geochemistry climate planet

Use of By-Products from the Tequila Industry. Part 12: Composted Agave Bagasse for Growing Grape Tomatoes

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American Journal of Plant Sciences 2022年第9期13卷 1227-1232页

作者： Gilberto Íñiguez-Covarrubias Walter Ramírez-Meda José de Jesús Bernal-Casillas Gil Virgen-Calleros departamento de Madera Celulosa y Papel Centro Universitario de Ciencias Exactas e Ingenierías Universidad de Guadalajara Guadalajara México departamento de ingeniería de Proyectos Centro Universitario de Ciencias Exactas e Ingenierías Universidad de Guadalajara Guadalajara México departamento de Producción Agrícola Centro Universitario de Ciencias Biológicas y Agropecuarias Universidad de Guadalajara Guadalajara México

Here, we evaluated the possibility of growing grape tomatoes on three different mixtures of composted agave bagasse substrate. Tomatoes were grown in 28-L pots for 106 days under a drip irrigation system with a hydroponic crop nutrient solution. The average production of grape tomatoes was 338.9, 358.9, and 325.7 g/pot/cut for each of the substrates studied, and no significant difference was observed between treatments (p > 0.5). The mean of numbers of grape tomatoes were 34.6, 38.8, and 34.2/pot/cut for each of the substrates studied, and no significant difference was observed between treatments (p > 0.5). The mean weight of individual grape tomatoes was about 10.4 g for all of the substrates tested. These results confirmed the notion that a composted agave bagasse substrate could replace an expensive imported substrate. The remaining challenge is to produce agave bagasse substrate commercially, because to date, agave bagasse substrates have only been produced on a pilot scale for testing. Therefore, it is necessary to implement a stabilized process for producing agave bagasse at a commercial level. This process must consider economic production costs and market value to ensure that the product is competitive with other substrates typically used in soilless crops.

关键词： Agave Bagasse Grape Tomatoes Tequila Industry

Pseudostress-BasedMixed Finite Element Methods for the Stokes Problem in Rn with Dirichlet Boundary Conditions.I:A Priori Error Analysis

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Communications in Computational Physics 2012年第6期12卷 109-134页

作者： Gabriel N.Gatica Antonio Marquez Manuel A.Sanchez CI2MA and departamento de ingenier´ıa Matem´atica Universidad de Concepci´onCasilla 160-CConcepcionChile departamento de Construcci´on e ingenier´ıa de Fabricacion Universidad de OviedoOviedoEspa-na.

We consider a non-standard mixed method for the Stokes problem in Rn,n∈{2,3},with Dirichlet boundary conditions,in which,after using the incompressibility condition to eliminate the pressure,the pseudostress tensor s and the velocity vector u become the only unknowns.Then,we apply the Babuˇska-Brezzi theory to prove the well-posedness of the corresponding continuous and discrete formulations.In particular,we show that Raviart-Thomas elements of order k≥0 for s and piecewise polynomials of degree k for u ensure unique solvability and stability of the associated Galerkin scheme.In addition,we introduce and analyze an augmented approach for our pseudostress-velocity formulation.The methodology employed is based on the introduction of the Galerkin least-squares type terms arising from the constitutive and equilibrium equations,and the Dirichlet boundary condition for the velocity,all of them multiplied by suitable stabilization parameters.We show that these parameters can be chosen so that the resulting augmented variational formulation is defined by a strongly coercive bilinear form,whence the associated Galerkin scheme becomes well posed for any choice of finite element subspaces.For instance,Raviart-Thomas elements of order k≥0 for s and continuous piecewise polynomials of degree k+1 for u become a feasible choice in this case.Finally,extensive numerical experiments illustrating the good performance of the methods and comparing them with other procedures available in the literature,are provided.

关键词： Mixed finite element pseudostress incompressible flow

旋转输运速度场积分SPH对流扩散方程解的收敛性

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Acta Mechanica Sinica 2023年第2期39卷 61-70页

作者： Pablo Eleazar Merino-Alonso Fabricio Macià Antonio Souto-Iglesias departamento de Arquitectura Constructión y Sistemas Oceánicos y NovalesUniversidad Politécnica de MadridMadridSpain departamento de Matemática e Informática Aplicadas a las ingenierías Civil y Naval Universidad Politécnica de MadridMadridSpain

本文在刚性旋转输运速度场的特殊情况下,建立了二维平流扩散方程的积分光滑粒子流体动力学(SPH)解的收敛性.考虑了Morris等人对拉普拉斯算子的近似,在傅里叶空间中建立了SPH解与精确解的收敛性.证明了如果满足核的傅里叶变换的某个条件... 详细信息

本文在刚性旋转输运速度场的特殊情况下,建立了二维平流扩散方程的积分光滑粒子流体动力学(SPH)解的收敛性.考虑了Morris等人对拉普拉斯算子的近似,在傅里叶空间中建立了SPH解与精确解的收敛性.证明了如果满足核的傅里叶变换的某个条件,即我们称之为正条件,则收敛是有保证的.这个条件是核的傅里叶变换其径向轮廓的一阶矩为正,并通过数值验证说明了分析结果.根据L2范数和最大范数,比较了使用不同核包括SPH社区更常用的核(即Wendland核以及三次和线性样条核)获得的数值解.除此之外,提出并测试了一个病理核,该核不满足正条件,导致了非收敛结果.这一事实表明,在对流扩散方程的情况下,正条件不仅是收敛的充分条件,也是必要条件.

关键词： Smoothed particle hydrodynamics Numerical analysis Diffusion Convergence Fourier analysis

Analysis of the role of diffraction in topographic site effects using boundary element techniques

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Earthquake Science 2013年第5期26卷 341-350页

作者： Juan Gomez Doriam Restrepo Juan Jaramillo Camilo Valencia departamento de ingeniería Civil Universidad EAFITMedellín Colombia

The role played by the diffraction field on the problem of seismic site effects is studied. For that purpose we solve and analyze simple scattering problems under P and SV in-plane wave assumptions, using two well known direct boundary-element-based numerical methods. After establishing the difference between scattered and diffracted motions, and introducing the concept of artificious and physically based incoming fields, we obtain the amplitude of the Fourier spectra for the diffracted part of the response： this is achieved after establishing the connection between the spatial distribution of the transfer function over the studied simple topographies and the diffracted field. From the numerical simulations it is observed that this diffracted part of the response is responsible for the amplification of the surface ground motions due to the geometric effect. Furthermore, it is also found that the diffraction field sets in a fingerprint of the topographic effect in the total ground motions. These conclusions are further supported by observations in the time-domain in terms of snapshots of the propagation patterns over the complete computational model. In this sense the geometric singularities are clearly identified as sources of diffraction and for the considered range of dimensionless frequencies it is evident that larger amplifications are obtained for the geometries containing a larger number of diffraction sources thus resulting in a stronger topographic effect. The need for closed-form solutions of canonical problems to construct a robust analysis method based on the diffraction field is identified.

关键词： Seismic site effects Topographiceffects Elastic wave scattering Diffractionof in-plane waves

Preface to the Focused Issue on High-Order Numerical Methods for Evolutionary Pdes

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Communications on Applied Mathematics and Computation 2023年第2期5卷 529-531页

作者： Arturo Hidalgo Michael Dumbser Eleuterio F.Toro departamento de ingeniería Geológica y Minera Escuela Técnica Superior de Ingenieros de Minas y EnergíaCenter for Computational SimulationUniversidad Politécnica de MadridRíos Rosas2128003 MadridSpain department of Civil Environmental and Mechanical EngineeringUniversity of TrentoVia Mesiano 7738123 TrentoItaly

The underlying fields of this special issue of CAMC include mathematical modeling through evolutionary partial differential equations(Pdes),advanced high-order non-lin-ear numerical methods for their approximation and applications in various engineering branches,in physics,biology and medicine,to name but a few.Of special interest are math-ematical models based on systems of hyperbolic balance laws,including stiff source terms.

关键词： hyperbolic stiff approximation

Changes in Olsen P in Relation to P Balance in Contrasting Agricultural Soils

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Pedosphere 2016年第5期26卷 636-642页

作者： Isabel DIAZ Jose TORRENT departamento de ingeniería Aeroespacial y Mecánica de Fluidos Escuela Tdcnica Superior de Ingeniería Agronómica(ETSIA)Universidad de SevillaCtra de Utrera km 141013 Sevilla(Spain) departamento de Agronomia Universidad de CordobaEdificio C4Campus de Rabanales14071 Cordoba(Spain)

Maintaining soil phosphorus(P) at adequate levels for plant growth requires assessing how the long-term P balance(viz., the difference between P inputs and outputs) results in changes in soil test P. The hypothesis that routinely measured soil properties can help predict the conversion factor of P balance into Olsen P was tested at 39 sites in agricultural areas of the Mediterranean region in Spain. A set of soil samples from each site was analyzed for Olsen P, inorganic P(P extracted using 0.5 mol L^(-1) H_2SO_4), pseudototal P(P extracted using 0.5 mol L^(-1) H_2SO_4 following ignition at 550℃), and organic P(the difference between pseudototal P and inorganic P). Organic and Olsen P were uncorrelated in most of the 39 soil sets, which suggests that organic P content changed little with P inputs and outputs. The slopes of the regression lines of Olsen P against pseudototal and inorganic P, which were used as two different measures of the conversion factor, ranged widely(from 0.03 to 0.25 approximately), with their average values(about 0.10) being similar to those found in long-term experiments conducted in temperate areas. Neither conversion factor was significantly correlated with any routinely measured soil property; however, the conversion factor for inorganic P was significantly lower for calcareous soils than for noncalcareous soils. Our negative results suggest the need to isolate the influence of soil properties from that of management systems and environmental factors relating to P dynamics in future studies.

关键词：磷素平衡农业土壤 H2SO4 土壤性质土壤测试转换因子常规测量石灰性土壤