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Live above-and belowground biomass of a Mozambican evergreen forest:a comparison of estimates based on regression equations and biomass expansion factors

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Forest Ecosystems 2016年第1期3卷 1-12页

作者： Tarquinio Mateus Magalhāes Departamento de Engenharia Florestal Universidade Eduardo MondlaneCampus Universitario

Background： Biomass regression equations are claimed to yield the most accurate biomass estimates than biomass expansion factors （BEFs）. Yet, national and regional biomass estimates are generally calculated based on BEFs, especially when using national forest inventory data. Comparison of regression equations based and BEF-based biomass estimates are scarce. Thus, this study was intended to compare these two commonly used methods for estimating tree and forest biomass with regard to errors and biases. Methods： The data were collected in 2012 and 2014. In 2012, a two-phase sampling design was used to fit tree component biomass regression models and determine tree BEFs. In 2014, additional trees were felled outside sampling plots to estimate the biases associated with regression equation based and BEF-based biomass estimates; those estimates were then compared in terms of the following sources of error： plot selection and variability, biomass model, model parameter estimates, and residual variability around model prediction. Results： The regression equation based below-, aboveground and whole tree biomass stocks were, approximately, 7.7, 8.5 and 8.3 % larger than the BEF-based ones. For the whole tree biomass stock, the percentage of the total error attributed to first phase （random plot selection and variability） was 90 and 88 % for regression- and BEF-based estimates, respectively, being the remaining attributed to biomass models （regression and BEF models, respectively）. The percent bias of regression equation based and BEF-based biomass estimates for the whole tree biomass stock were -2.7 and 5.4 %, respectively. The errors due to model parameter estimates, those due to residual variability around model prediction, and the percentage of the total error attributed to biomass model were larger for BEF models （than for regression models）, except for stem and stem wood components. Conclusions＂ The regression equation based biomass stocks were found to be slightly larg

关键词： Androstachysjohnsonii Prain Mecrusse Root growth Biomass additivity Double sampling Forest biomassinventory Carbon allocation

Numerical Simulation of Sub-cooled Cavitating Flow by Using Bubble Size Distribution

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Journal of Thermal Science 2003年第4期12卷 350-356页

作者： Yutaka ITO es.titech.ac.jp Hideki WAKAMATSU es.titech.ac.jp Takao NAGASAKI es.titech.ac.jp Department of Energy Sciences Tokyo Institute of Technology 4259 Nagatsuta-cho Midori-ku Yokohama 226-8502 Japan E-mail: itoDepartment of Energy Sciences Tokyo Institute of Technology 4259 Nagatsuta-cho Midori-ku Yokohama 226-8502 Japan E-mail: itoDepartment of Energy Sciences Tokyo Institute of Technology 4259 Nagatsuta-cho Midori-ku Yokohama 226-8502 Japan E-mail: ito

A new cavitating model by using bubble size distribution based on mass of bubbles is proposed. Liquid phase is treated with Eulerian framework as a mixture containing minute cavitating bubbles. Vapor phase consists of various sizes of minute vapor bubbles, which is distributed to classes based on their mass. The change of bubble number density for each class was solved by considering the change of bubble mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method the mass of bubbles is treated as an independent variable, in other word, a new coordinate, and dependant variables are solved in Eulerian framework for spatial coordinates and bubble-mass coordinate. The present method is applied to a cavitating flow in a convergent-divergent nozzle, and the two-phase flow with bubble size distribution and phase change was successfully predicted.

关键词： cavitation numerical simulation liquid nitrogen bubble size distribution.

Evaluation of a novel Asymmetric Genetic Algorithm to optimize the structural design of 3D regular and irregular steel frames

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Frontiers of Structural and Civil Engineering 2020年第5期14卷 1110-1130页

作者： Mohammad Sadegh es-HAGHI Aydin SHISHEGARAN Timon RABCZUK School of Civil Engineering Khajeh Nasir Toosi University of TechnologyTehran 19697-64499Iran School of Civil Engineering Iran University of Science and TechnologyTehran 13114-16846Iran Division of Computational Mechanics Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam

We propose a new algorithm,named Asymmetric Genetic Algorithm(AGA),for solving optimization problems of steel *** AGA consists of a developed penalty function,which helps to find the best generation of the *** objective function is to minimize the weight of the whole steel structure under the constraint of ultimate loads defined for structural steel buildings by the American Institute of Steel Construction(AISC).Design variables are the cross-sectional areas of elements(beams and columns)that are selected from the sets of side-flange shape steel sections provided by the *** finite element method(FEM)is utilized for analyzing the behavior of steel frames.A 15-storey three-bay steel planar frame is optimized by AGA in this study,which was previously optimized by algorithms such as Particle Swarm Optimization(PSO),Particle Swarm Optimizer with Passive Congregation(PSOPC),Particle Swarm Ant Colony Optimization(HPSACO),Imperialist Competitive Algorithm(ICA),and Charged System Search(CSS).The results of AGA such as total weight of the structure and number of analyses are compared with the results of these *** performs better in comparison to these algorithms with respect to total weight and number of *** addition,five numerical examples are optimized by AGA,Genetic Algorithm(GA),and optimization modules of SAP2000,and the results of them are *** results show that AGA can decrease the time of analyses,the number of analyses,and the total weight of the *** decreases the total weight of regular and irregular steel frame about 11.1%and 26.4%in comparing with the optimized results of SAP2000,respectively.

关键词： optimization steel frame Asymmetric Genetic Algorithm constraints of ultimate load constraints of serviceability limits penalty function

Association between Tropical Convection and Boreal Wintertime Extratropical Circulation in 1982/83 and 1988/89

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Advances in Atmospheric Sciences 2003年第4期20卷 593-603页

作者： ja-Yeon MOON Kyung-ja HA Climate Research Laboratory Meteorological Research InstituteSeoul156-720KoreaDepartment of Atmospheric SciencesPusan National UniversityPusan609-735Korea

Boreal wintertime extratropical circulation is studied in relation to the tropical convection during the 1982/83 El Niño and 1988/89 La Niña. The anomaly structure of 1982/83 and 1988/89 over the extratropics reveals remarkably different features as the longitudinal tropical forcing region changes. The Rossby wave source (Positive) shows the largest maximum over East Asia in both years due to the persistent heating from the western Pacific warm pool area. However, the sink term shows contrasting features over the subtropics and extratropics between the two years. In the El Niño year, enhanced tropical convection over the eastern Pacific produces the Rossby wave sink at 10°N and shifted eastward over the North Pacific, while in the La Niña year, the sink area is shifted westward over the North Pacific. The contrasting features between the two events in mean-eddy interaction appears especially over the downstream area of the East Asian Jet. The extension (retraction) of the meanflow eastward (westward) to the east (west) of the dateline is related with the effect of the westward (eastward) E-vector and the strengthening (weakening) of the negative anomalies of the barotropic growth of kinetic energy. Hence, almost opposite characteristics between the two events can explain the close relationship of tropical convection and the extratropical internal variability.

关键词： tropical convection extratropical circulation rossby wave source mean-eddy interaction

ASYMPTOTICS OF THE CROSS-VARIATION OF YOUNG INTEGRALS WITH ResPECT TO A GENERAL SELF-SIMILAR GAUSSIAN PROCesS

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Acta Mathematica Scientia 2020年第6期40卷 1941-1960页

作者： Soukaina DOUISSI Khalifa es-SEBAIY Soufiane MOUSSATEN Laboratory LIBMA Faculty SemlaliaUniversity Cadi Ayyad40000 MarrakechMorocco Department of Statistics and Probability Michigan State UniversityEast LansingMI 48824USA Department of Mathematics Faculty of ScienceKuwait UniversityKuwait Faculty of Sciences Mohamed first University OujdaMorocco

We show in this work that the limit in law of the cross-variation of processes having the form of Young integral with respect to a general self-similar centered Gaussian process of orderβ∈(1/2,3/4]is normal according to the values ofβ.We apply our results to two self-similar Gaussian processes:the subfractional Brownian motion and the bifractional Brownian motion.

关键词： self-similar Gaussian processes Young integral Breuer-Major theorem subfractional Brownian motion bifractional Brownian motion

Ductile Phase Toughened Brittle Materials

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Journal of Materials Science & Technology 1996年第2期12卷 124-134页

作者： Sun, XD Yeomans, ja UNIV SURREY DEPT MAT SCI & ENGNGUILDFORD GU2 5XHSURREYENGLAND

Toughening of brittle materials by the inclusion of ductile phases is governed by several important factors which include ceramic-ductile phase interfacial bond strength, physical and chemical compatibility between ceramic and ductile phase, geometry and mechanical properties of ductile phase. The present understanding of the effect of these factors on toughening is reviewed and clarified. Continuous ductile phases (network, fibre or plate) are found to be more efficient for the toughening of brittle materials than discrete ductile particles. However, ductile particle toughened brittle materials have the advantages of material homogeneity, isotropy, and particularly better high temperature properties. It has been demonstrated that the influence of interfacial bond strength is determined by the geometry of the ductile phase in the composites. For the comparatively continuous ductile phase, such as ductile network, fibre or plate, comparatively weak interfacial bond strength can promote partial debonding of the brittle matrix-ductile phase interface during crack propagation and is beneficial for toughening. For discrete particulate ductile phase toughened brittle materials, the small gauge length of the ductile phase often results in the ductile phase pull-out during crack propagation which is the main limitation to toughening. Thus strong bond strength is required to ensure the bridging of the crack by the ductile phase. The coefficient of thermal expansion (CTE) mismatch between matrix and ductile phase has also been correlated with the geometry of the ductile phase. In most of the ceramic/metal systems, the CTE of the ductile metal phase is greater than that of the ceramic matrix. In the case of ductile network, fibre or plate, the residual stress created by the CTE mismatch can contribute to toughening through its influence on the initial crack opening stress while the bridging of the crack by the ductile phase is still ensured. However, for discrete ductile parti

关键词： Brittleness

ON TRANSMISSION PROBLEM FOR KIRCHHOFF TYPE WAVE EQUATION WITH A LOCALIZED NONLINEAR DISSIPATION IN BOUNDED DOMAIN

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Acta Mathematica Scientia 2012年第3期32卷 893-906页

作者： Jeong ja Bae Department of Mathematics Dongeui UniversityPusan 614-714Korea

In this article, we consider the global existence and decay rates of solutions for the transmission problem of Kirchhoff type wave equations consisting of two physi- cally different types of materials, one component is a Kirchhoff type wave equation with nonlinear time dependent localized dissipation which is effective only on a neighborhood of certain part of the boundary, while the other is a Kirchhoff type wave equation with nonlinear memory.

关键词： Existence of solution uniform decay transmission problem Kirchhoff type wave equation boundary value problem localized dissipation

On Uniform Decay for Transmission Problem of Kirchhoff Type Viscoelastic Wave Equation

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Acta Mathematica Sinica,English Series 2010年第7期26卷 1197-1206页

作者： Jeong ja BAE Department of Mathematics Dongeui University

In this paper we consider the large time behavior of solutions to an n-dimensional transmission problem for two Kirchhoff type viscoelastic wave equations, that is, the wave propagation over bodies consisting of two physically different types of materials. One component is a simple elastic part while the other is a viscoelastic component endowed with a long range memory. We show that the dissipation produced by the viscoelastic part is strong enough to produce exponential or polynomial decay of the solution

关键词： existence of solution uniform decay wave equation boundary value problem a priori estimates

GLOBAL EXISTENCE FOR THE NONHOMOGENEOUS QUASILINEAR WAVE EQUATION WITH A LOCALIZED WEAKLY NONLINEAR DISSIPATION IN EXTERIOR DOMAINS

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Acta Mathematica Scientia 2009年第5期29卷 1203-1215页

作者： Jeong ja Bae Department of Mathematics University of Ulsan

It is proved that the global existence for the nonhomogeneous quasilinear wave equation with a localized weakly nonlinear dissipation in exterior domains.

关键词： quasilinear wave equation localized weakly nonlinear dissipation exterior domains